# Forum Home Renovation Retaining Walls  Replacement/Repair of Retaining Wall

## Smergen

Hi Gang, 
I've decided to stop hijacking Shauck's Go to Whoa thread (its awesome if you haven't seen it) and document my retaining wall project here, which is a much more logical and appropriate place for it. 
Basically to cut a long story short, a retaining wall built previously to us buying our house was poorly built but stable-ish. It would have needed a bit of TLC at some stage in the future. 
However given the recent downpour we've had down this part of the world, a huge amount of runoff from the housing development immediately behind us began flowing through our fence, and through the retaining wall. It was a result of the construction removing an overland table/spoon drain prior to constructing something more permanent. Either way, the wall sees a lot of natural sub-surface flow but this amount of water tipped it over the edge. 
The drain over the fence has since been reinstated but my wall and area needs some serious rehab. The Site Manager is an excellent bloke and has offered to help us out with whatever we need so we're happy with all that. 
So for now, I've got to plan how I'm going to do this work, given the fact I've never done something of this magnitude before. 
My initial plan is to bring the wall in a fair chunk to give the fence a reprieve and square the meeting point at 90deg. I don't want to replace all the wall as the lower parts are more than fine and doing a fantastic job. So I need to set out a plan on how to incorporate the new wall in with the old one. Drainage behind the wall will be a key issue, but I'm confident that I can possibly tap into the storm drain nearby (once I locate it!) 
So I welcome any thoughts, tips, advice and tricks as I embark on this job, because quite frankly, I have no idea! 
Here's some photos of the site which hopefully will help set the scene...

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## shauck

Hi Smergen. I followed you here as I'm very interested in how all this will work. Keen to hear what others will advise. 
I was wondering just a couple of things. When you say "bring the wall in a fair chunk", do you mean rebuild it in front of the previous wall or something else? 
I was also wondering, are the posts too small even where the lower wall is that is working? 
This is probably obvious and unnecessary of me to point out.  Think about finding the storm water drain before digging any trench for drainage so that you can get a continuous, even slight fall towards it. Council will know exactly where it is. Permission to use it is easy to get and a cheap fee. 
Just a few useful things I've found online. 
Cheers, Su.

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## Master Splinter

If you want to keep the existing retaining wall, and it's generally sound and not leaning in, my suggestion would be to build a new wall 600-800mm high about a meter in from what you already have.   
This'll give you a nice working height garden bed (ideal for veggies) as well as providing a bit of support to the the old wall (not a lot, but a bit!). 
Before putting the wall in, excavate down maybe 100mm (to make sure you can intercept runoff from the existing wall) then fill the bottom 2-300mm of the new section with drainage gravel, geotextile and agdrain.

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## Smergen

Thanks for all the info Su, will have a look through that tonight.   

> I was wondering just a couple of things. When you say "bring the wall in a fair chunk", do you mean rebuild it in front of the previous wall or something else?

  Yeah the intention is to build it in front of the other wall if I can. It's a bit of dead space out the back so it's not critical to maximise my room. I also think the first wall is far too close to the fence, and once someone builds up on the right hand side, I'd hate the weight of their drive and such put more stress on it.   

> I was also wondering, are the posts too small even where the lower wall is that is working?

  In the lower parts of the wall, the posts seem to be holding just fine. Basically they are good enough for the walls that are up to ~500mm but over that and there is too much pressure.   

> This is probably obvious and unnecessary of me to point out. Think about finding the storm water drain before digging any trench for drainage so that you can get a continuous, even slight fall towards it. Council will know exactly where it is. Permission to use it is easy to get and a cheap fee

  Well my current intention is to just follow the overflow line from the big rainwater tank we have about 1-2m away (just out of shot). It's overflow connects straight into the drain so I might just hook into that to save any application (am I right there?) or do as you suggest and find the council asset.

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## Smergen

> If you want to keep the existing retaining wall, and it's generally sound and not leaning in, my suggestion would be to build a new wall 600-800mm high about a meter in from what you already have.  
> This'll give you a nice working height garden bed (ideal for veggies) as well as providing a bit of support to the the old wall (not a lot, but a bit!). 
> Before putting the wall in, excavate down maybe 100mm (to make sure you can intercept runoff from the existing wall) then fill the bottom 2-300mm of the new section with drainage gravel, geotextile and agdrain.

  Thanks MS. 
Unfortunately I reckon the old wall has got a bit too much of a lean to it. Having said that our intention is to just have some growing plants as shields in there so that may be an option... hmm... (insert thinking music...) 
As for intercepting drain from existing wall, I doubt there is one, hence the build up and often seen leaking from between sleepers. I imagine if I just build infront of this one, the problem will remain. 
If I did build a new one and leave the old in place, would people think it would be possible to drill a few holes in the lower sleepers, cover with mesh/geo and have it drain straight into the gravel and drain section of the new wall?  :Rolleyes:  
But I do kind of like the idea of just building in front. Would save me a heap of trouble and dare I say effort. An extra garden bed wouldn't go astray either. I just don't want to cover up the existing problem and find the weight of the old wall and its drainage (or lack thereof) is too much for the new one...

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## shauck

> Thanks for all the info Su, will have a look through that tonight.   
> Yeah the intention is to build it in front of the other wall if I can. It's a bit of dead space out the back so it's not critical to maximise my room. I also think the first wall is far too close to the fence, and once someone builds up on the right hand side, I'd hate the weight of their drive and such put more stress on it.  _Sounds like a good plan_  
> In the lower parts of the wall, the posts seem to be holding just fine. Basically they are good enough for the walls that are up to ~500mm but over that and there is too much pressure.  _I just wonder if you might like all your walls to look the same and rebuild the whole lot for that reason alone. I'm a bit funny like that but maybe you don't mind_ 
> Well my current intention is to just follow the overflow line from the big rainwater tank we have about 1-2m away (just out of shot). It's overflow connects straight into the drain so I might just hook into that to save any application (am I right there?) or do as you suggest and find the council asset.

  _Also sounds like a good simple plan. I personally wouldn't bother asking council if you are already hooked to the drain._

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## shauck

> Thanks MS. 
> Unfortunately I reckon the old wall has got a bit too much of a lean to it. Having said that our intention is to just have some growing plants as shields in there so that may be an option... hmm... (insert thinking music...) 
> As for intercepting drain from existing wall, I doubt there is one, hence the build up and often seen leaking from between sleepers. I imagine if I just build infront of this one, the problem will remain. 
> Just make sure you run drainage at base of new wall. I reckon it should take care of any water coming through 
> If I did build a new one and leave the old in place, would people think it would be possible to drill a few holes in the lower sleepers, cover with mesh/geo and have it drain straight into the gravel and drain section of the new wall?  
> Couldn't hurt but I also wondered (not with any claim to expert knowledge), why not remove the upper section of the old wall after backfilling some of the new wall just so you can really have some soil in there for garden bed and be able dig with a spade without hitting sleepers below the surface. Just take a chainsaw to it. ?? 
> But I do kind of like the idea of just building in front. Would save me a heap of trouble and dare I say effort. An extra garden bed wouldn't go astray either. I just don't want to cover up the existing problem and find the weight of the old wall and its drainage (or lack thereof) is too much for the new one...

  I reckon, if you build the wall according to specs then whatever is behind it, wall and all, will hold in place. (again, not an expert) 
Cheers, Su.

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## Smergen

At this stage I'll layout the wall prior to commencement and see how a wall in front will look, and whether or not I think it will withhold the soil and load behind it. Being a risk averse person I can assure you that it will be solid whatever it is. 
I've read about 'blue metal' as a back fill. Would that be suitable, or will and run of the mill gravel work? 
And geo-fabrics... the stuff from the big green shed suffice?

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## shauck

I was told to use scoria by several people, including the guy who excavated my driveway. It has the added advantage of being very light to shovel and carry in a wheelbarrow. In my neck of the woods it cost 50 bucks a cubic meter but it may be cheaper other places. 
With geofabric, there is no clear consensus on it's benefit. Some say it's not necessary. I used it but hey, who knows. It's not cheap either. 
Cheers, Su.

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## Smergen

One thing I'd like to put to the forum is the corner where the new wall will meet. 
Let's say that I am running the two sections perpendicular to each other. Since the walls are angled back (not straight out of the ground) a gap will occur where the two sections of wall will meet in the corner. So I'm trying to work out how I would 'bridge the gap'. 
Any thoughts?

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## shauck

I wondered about this too. I was going to build the wall with a batter but then I used steel posts and decided not to.  
In my head, I envisioned that I would have put a post in the corner that leant back in both directions and that the wales ends that met behind the corner post would be cut on an angle (top edge longer than bottom edge) and each wale slightly longer than the one below. 
Fortunately for me I didn't have to find out if this works.

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## cherub65

> One thing I'd like to put to the forum is the corner where the new wall will meet. 
> Let's say that I am running the two sections perpendicular to each other. Since the walls are angled back (not straight out of the ground) a gap will occur where the two sections of wall will meet in the corner. So I'm trying to work out how I would 'bridge the gap'. 
> Any thoughts?

  
They simply over lap, one course butts up with the angle cut, the other course is longer. Next course alternate butt joint, set posts 200-300 mm back from corner

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## Smergen

> They simply over lap, one course butts up with the angle cut, the other course is longer. Next course alternate butt joint, set posts 200-300 mm back from corner

  Thanks Cherub, let's make sure I follow you right... Basically I won't put a post in the corner and then cut the ends of the sleepers at an angle so they sit flush. Correct? 
I suppose the incline of the posts isn't that significant... 
Had 45 sleepers delivered yesterday. Will start on site clean up this evening after work and kids if the weather holds off. Photos will commence from then on.

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## shauck

I think what cherub is saying is that one sleeper will run past and the other will butt into it and then you alternate this with each course. Is that right?

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## cherub65

> I think what cherub is saying is that one sleeper will run past and the other will butt into it and then you alternate this with each course. Is that right?

  Thats correct.

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## Smergen

OK, you've lost me a little here. Alternating course? Is this implying that I stagger the lengths within the wall so the joins where one wale ends and the next start aren't in line? My intention was simply to put the wales at their full length (2.4m), put a post there (so 'join' is there) and a post in the middle (i.e. 1.2m centres) for additional support if required by the info Shauck supplied above.

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## shauck

If you check out the pic below you will see how one row of wales meet. All you do is alternate this so one row runs past on one side then the next row runs past on the other side.  
The wale that butts into the other one will have it's end cut on the angle that the wall is battered to (leans). You can use a bevel to work out this cut

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## Smergen

> If you check out the pic below you will see how one row of wales meet. All you do is alternate this so one row runs past on one side then the next row runs past on the other side.  
> The wale that butts into the other one will have it's end cut on the angle that the wall is battered to (leans). You can use a bevel to work out this cut

  Thanks Su, that now makes perfect sense. I'm really not sure why I was having so much trouble with the concept!  :Doh:

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## Smergen

Progress was a little slow over the Xmas break, but I can report that the 11 post holes are dug. It proved to be a lot more work than I thought and thankfully had my bro on site to give me a hand with the so called 'one man post hole digger'. 
Now with the kids back at the ranch, installing posts will be more difficult but I'm hoping to get one or two lined up a night so that they can be cured and ready to roll in a few weeks time for the wales. 
Bit of a concern that we could only put the holes 900mm deep when I think they should have been a 1m, but the auger wouldn't go further and no time to get an extension. I'm hoping that by keeping the some (or all) of the existing wall in place, it will hold a lot of the load off the new wall. Still in two minds about that. Thoughts welcome. 
Also need to design a jig to keep the posts in their correct allignment while the concrete cures. I was just going to use a couple of bits of pine nailed on both sides. Will see how solid they go once in the holes. 
Photos will hopefully come tonight when I get them off the camera.

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## Smergen

A couple of shots if people are interested, starting with the site to clean up, and progressing through. A couple thrown in there to show how bad the old was is and how bad the erosion got. Also of the digger for the day and our last two holes...

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## Smergen

OK, 3 posts went in over the weekend. It seemed I underestimated the amount of concrete required to fill the holes!  :Smilie:  About 5.5 x 20kg bags went down along with the posts to set them. I'm hoping this would suffice, and I'd hate to see how big they'd have to be if it wouldn't! 
With rain forecast for this week, I'm reluctant to try and get some more done. Will see how things have held up tonight. 
More progress photos coming a little later on...

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## Moondog55

Thanx for the photos, and any update is appreciated

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## Smergen

Well I might post these photos in 2 parts... the good and the bad... 
So this was the progress over the weekend. Was very happy with the layout and the scoping of the wall. Really started to make it 'come to life' and see how it may look. 
Also set 3 posts set and very happy with them. Surprised how easily it was, and the General Manager helped out with the level while I shovelled the concrete. Was surprised how much concrete it used to fill in the holes.

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## Smergen

Arrrggghhh!!!!! 
It. Is. Summer! 
Ahh... that's better. Vented. 
I knew we had a bit of rain today, but I didn't think we had that much. I was wrong... Went out to check if if I had some puddles and a bit of mud. Oh did I what. I had 8 nice really well defined puddles about 2ft deep... doh! 
So it's a bit of stop work while we try and ride out the rain this week. 
Does anyone have any suggestion on how long I'd have to wait until I can go to work and set the posts? I imagine they don't need to be bone dry, but we do have clay now well mixed in the scoria. Should I remove it and reset the holes completely? 
Either way, I'm going to need a nice dry couple of days to at least allow me to move around the site! 
At least we got the corner posts in, so I can go ahead and measure and cut those pieces in the shed while I wait for Summer to get its @@@@ out of bed.

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## shauck

This rain is insane. (poet) 
I had a little rain in a couple of holes when we poured the concrete and it just pushed out the top of the hole when filled them. This was a guy from Boral who said it was alright. 
Cheers, Su.

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## Smergen

Thanks Su, this rain is plainly insane(ly). 
A heap more overnight as you'd know and the work area just looks like a swamp. It is really making me think what I'll do with the area even once the wall is finished. I'm going to need to regrade it and throw some crushed rock down I think. 
A good side of this I suppose is that the holes have got a little bigger so the footings will be all that much stronger once we get the water out. Just need more concrete. 
Will just leave it be and make sure the shed doesn't flood for the rest of the week if this keeps up. Then hopefully dry next week I can start on site clean up and get cracking again...

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## shauck

If your holes aren't full already (probably), could you cover them with some sort of lid to keep them a bit dry?  
It's really hard to sit out the rain when you have so much to do. Perhaps some scrabble or a good book to take your mind off it. Turn the radio up loud and shut the curtains so you can't hear or see the rain and pretend you meant to take a break.

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## Smergen

Another night of consistent rain in the Marsh... 
A quick check this morning of overnight damage and one hole is full to brim and the rest are at least half full. I did try and cover 3 to see if that helps, but I couldn't tell as there was water sitting on top of them! I'm not holding out hope. 
I know what you are saying about the radio/curtains though Su. Everytime a burst of rain comes through, I break out into a cold sweat with mental images of the water pouring through like last time. The spoon drain up the back is holding steady though. 
Still no major flooding elsewhere around the house/shed/wall so we're coping OK. 
When you look at the devestation up north there is no way I'm going to complain about the problems I have. It almost makes you feel guilty for whinging.

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## shauck

My brother and his son live in Toowoomba of all places. It was a relief to find out he is on high ground there. It's hard to believe that a town was so badly in drought, they were considering recycling waste water for drinking. The rain we are experiencing is really just a nuisance in comparison.

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## Smergen

OK, I unfortunately was away all weekend so there was no progress on the wall. But to be honest it wasn't too bad I suppose at it gave the site a chance to dry out. Managed to walk around it last night without going four foot into mud so after today's sun, will hopefully back to 'normal'. 
Will aim to re-dig out the holes with the hand post hole digger back down to their original depths. I really don't want to go and get that PHD  from the hire joint again... So I'm hoping the clay and mud that went in the holes hasn't 'set' down the bottom too hard. It will also still have the scoria in there so hopefully that will keep things a bit loose. 
Some holes are now considerably large than originally dug (if a little shallower!) so after a clean out, I'm going to need a few more bags of concrete. Not too worried, will only give the wall a better base structure I suppose.

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## shauck

Do you have scoria in the holes? How did that get in there?

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## Smergen

I put the scoria in there after digging them out the first time. A couple of good shovel loads in each. 
It actually worked a treat as I was able to dig out most of the mud out of all holes leaving just the scoria in a water trying to soak away, which is I guess exactly what it's supposed to do. 
Getting the bloke from the site behind us to drop off a few bags of cement and some crushed rock so the composition of the concrete for the other holes will be different to the bags of pre-mix 'just add water' concrete I used previously. Hopefully I get the mix right but given I'd need another $300 worth of the bunnings this works out saving me a few dollars. 
So inspecting the holes they are a little bigger in most cases but the depths look about the same. I'm hoping to get the next few posts in this week before the rain comes again.

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## shauck

Did someone suggest to put scoria in the hole? I've not heard of doing this. I wonder if it might allow the posts to sink a bit over time? Curious.

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## Smergen

I'm sure I read it in one of the tech sheet bits I got from this forum. I'll have to go check now, you've got me worried... 
I haven't started on the other 8 holes so can still get the scoria out of them, but the 3 I've done last week certainly have it at the bottom. In a way it help us get the posts level and on the angle we wanted as well. 
Anyone else got an opinion on scoria at the bottom of post holes?

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## shauck

Anyone care to add their opinion/knowledge on this. Does it help with drainage or just the opposite and with a retaining wall which has a bit of weight to it, unlike a fence, will there be any settling of the posts? 
I'm sure Smergen would like to get on with his work and may be sitting there looking at the scoria in the holes going should I or shouldn't I? And I feel like it's my fault for questioning his plan.  
I'm trying to find info on the gravel in the hole and it seems mostly  mentioned re. fence posts. Some good and bad said about it. Helps  drainage at bottom of post, etc but also some not convinced. See below  another forum post on this topic, again it's on fence posts.    Should I use gravel at bottom of post hole?  			 		   		brians
08-16-05, 08:31 AM 
		I  am getting ready to set 4x4's in 30" deep holes I've dug for my posts.   My question is should I use gravel at the bottom of the hole to help  drainage or will that not help to extend the life of the posts?  I know  the posts will rot out eventually but my goal is to get at least 15  years out of them.  Gravel doesn't cost much so if that will help I'll  do it.  
 		blwallen
08-22-05, 11:57 PM 
		I've  built a few fences and am still looking for the recipe for longevity.    Books generally recommend putting gravel in the bottom of each hole and  I've usually thought that poorly drained soil, for example with high  clay content, should have proportionately more gravel than holes in  sandy soil. 
I don't know how much this will improve the life of your posts, however.   Creosote used to be used to prolong wood contact soil, but it has been  found to be carcenogenic and it is n ow a controlled pesticide with EPA  regulations about time limits to different kinds of exposure.  My  current idea for improving post life in soil is to dip them in roofing [COLOR=blue ! important][COLOR=blue ! important]cement[/COLOR][/COLOR]  to a depth that allows about six inches of cement above ground level. I  hope this will encapsulate the post from soil water and that termites  will find roofing tar unappetizing. Consumer organization testing of  wood protection has shown that opaque stains provide better protection  than clear stains or wood preservatives.  I am coating the rest of the  post and the fence with such stain. [COLOR=blue ! important][COLOR=blue ! important]Metal[/COLOR][/COLOR] or vinal caps on the tops of posts keep water from entering. 
I just saw an article on this site recommending metal fence spikes that  you drive into the ground; a metal "socket" remains above the ground to  receive the bottom of the post.  My concern would be that the metal  might rust away in about the same time as the wood would rot in the  ground.  Obviously, heavier metal spikes would last longer than lighter  ones. These would certainly be easier to replace than wooden posts in  concrete which is laborious to remove and replace. 
   		mango man
08-23-05, 06:34 AM 
		I find in this area the rot happens at the point the post , leaves the ground not "40 down. 
  I just put up a fence and didnt bother with the gravel , didnt see  much point iin it since the water table was right at the 36" mark or so  and most of my posts are set in water   :Biggrin:   
 		Nevermore44
08-23-05, 03:18 PM 
		When putting my posts in i had a few observations.  
-- i added the gravel like most people say.. but when adding the  concrete, the cement would just fill in the gravel bed and encase  everything anyway... post end and all... so who knows. I poured it  wet... so maybe dry is a different story.   
--I have clay soil... so when the 36" holes were dug... and it rained..  the holes held the water for many days before draining. So I would think  that if the post end wasn't encased in cement... and the gravel bed  left a room for water to pool, that the post would just be pulling water  up constantly for days.. adding to rot. Now that it is summer... and  dry as a bone the earth as pulled away from the cement a bit.. so when  we do get rain... it has a direct path down.. so again.. if there was a  gravel chamber... it would fill and hold the water.  
--I mounded the cement around the post above ground level and added a  caulk to seal the connection as much as possible. I used some cement  stain to get it to a brown dirt color.. so it isn't so much an eye sore.  Looking back.. I wish I would have colored the cement as I poured it.  
--Also looking back.. i would have definitely considered the post  spikes. If you counter the initial cost with the wood that you aren't  going to be burying, the cement, time, the wood lasting longer,  and for  me rental cost of the auger.... i would go with the spikes.  
Looking back is so easy...    :Smilie:  
   		Kobuchi
08-24-05, 04:01 AM 
		The  metal spike is a good idea (post doesn't touch earth!), but I've yet to  see any that support the post well - I feel anything less than 10" up  the post isn't following through on an otherwise sound anchor. Also,  they're crazy expensive compared with much thicker metal available at  any scrapyard. 
What I do, is get some heavy steel at a scrap yard, and hack it into lengths about 16". I [COLOR=blue ! important][COLOR=blue ! important]drill[/COLOR][/COLOR]  two holes near the ends, at about 1" and 6". These set about 4" deep  into cement, formed with odds and ends so it's a few inches above grade  and pretty where you can see it. The posts don't touch earth, and may be  replaced some day without changing the anchor-bracket. And it costs  next to nothing. 
I did this once on a larger scale, for a clothesline post. 
There are also commercially made post brackets, for setting in cement. You pay a lot for what you get.

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## shauck

Just found this pdf brochure that uses gravel in the hole. Hope that helps.

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## Smergen

Su... you are an absolute star. Thanks heaps for looking into this for me. And no, you didn't put the 'fear of god' into me, but I was a little concerned. With the Site Manager out of action early last week, and me twinging my back on Thursday, nothing progressed during the week. And guess what? The rain is now back... grr.... 
With respect to the gravel, by the sounds of it it could go either way. So to keep with consistency (the 3 already in the ground have it) I shall keep the scoria at the bottom of each hole. That way if it does settle, hopefully it will happen uniformly!  :Smilie:  If for nothing else it helps the Site Manager level and set the post while I shovel in the concrete. 
One step I realised I missed those was to seal the ends of the posts, so the three in the ground have no sealent. Highly likely then that the wood will start to rot eventually. I hope with improved drainage around the wall, that won't happen for quite some time. 
In the mean time, I'll need to seal the remaining 8 ends. Anyone got any good recommendations for red gum sleepers and water sealants for posts? Am hoping the back improves enough this week to set a few later in the week. 
That's if the rain stops...

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## shauck

Glad to have cleared it up, sort of... I'm constantly wondering if I'm doing things the right way so don't mind me too much when I question something.  
I did read of using roofing tar for sealing the ends of posts in that last lot of info I gathered. Read below. They also said opaque stains are better than clear stains.

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## Bloss

> Glad to have cleared it up, sort of... I'm constantly wondering if I'm doing things the right way so don't mind me too much when I question something.  
> I did read of using roofing tar for sealing the ends of posts in that last lot of info I gathered. Read below. They also said opaque stains are better than clear stains.

  Opaque stains (& Paint) have more pigment and that is what provides the best UV resistance. With posts - depends bit on how you are installing them if they are simply rammed earth and no concrete then the posts is exposed to moisture anyway - gravel or no gravel. In a clay soil the gravel will simply mean there will be a pool of water for the post to sit in when the clay around is saturated rather than the wet clay itself. End result is the post will be wet so it needs to be treated or have some protective coating of some sort. There are a range of options for coatings. Key is to use a rot resistant species so durability Grade 1 (highly Durable) or 2 (Durable) for any in ground applications and treated if you want 25 years or more of in-ground life. Even on rammed earth posts I use a complete surround of concrete at the base - whether that has been worth it who knows, but I know there are original fences of mine still standing and in service after 40 years . . .

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## Smergen

Thanks for the tips bloss and makes complete sense. I was think that I make sure when I start shovelling in the concrete that I put a bit down so the post is complete surrounded by concrete. 
A quick question though would I coat the entire length of wood that is encased in the concrete or just the one that runs the risk of coming in contact with the base and gravel section? 
If this site is still running (and so am I) in 40 years, I'll log in to give an update of the wall!  :Smilie:

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## Smergen

OK, another 3 posts done. Hopefully will get the next 5 done over the next two nights so we can let them cure. 
Didn't treat them. Have decided I didn't want two construction techniques in different parts of the wall. I guess we'll see how they hold up. 
Photos coming at the end of the week.

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## stevoh741

> A quick question though would I coat the entire length of wood that is encased in the concrete or just the one that runs the risk of coming in contact with the base and gravel section?

  I wouldn't get too pedantic - when the sleepers dry out they will shrink and produce a gap between the sleeper and concrete anyway, so even incased in concrete, the sleeper will still get wet.

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## Smergen

Thanks Stevoh, 2 more posts down, three left. Hopefully done tomorrow.

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## Moondog55

I read about the shrinkage problem and to help with that I went around after the concrete had set and slapped on some wood preservative ( zinc napthenate based ) and a couple of days later some oil based paint.
As this was for shade sail posts and the strain over the last few gales has been tremendous I don't know if has done any good, but it is an option you could consider

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## Smergen

Hmm... that's not a bad idea Moondog. I'll get the final posts in, wait a week for it all to cure and set and look at what gaps and wood condition looks like. Still trying to work out where or how I'll run the ag pipe behind it, but I've got a bit of time to decide. 
By the way, did you find a pic of the house mate?  :Smilie:

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## Moondog55

LOL Not yet, if it was my house and wall I would be laying the slotted drainage pipe, maybe even  2 lots, and I'd be using gravel and geocloth too, that is a job I would not want to have to do again. 
I would suggest that you make a folder of the work that has been done; then; when and if you decide to sell you have a good visual record of what has been done, the buyer will know then that he has few worries about the standard of the building

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## Smergen

Yeah I'll be getting the ag-pipe in, and have a huge pile of scoria ready for the trench and backfill. I'm confident that the wall will outlast me at the house, but all wood will eventually rot I suppose... 
Nice tip on the folder, and I pretty much take a photo of all things done around the house. It's nice to reminisce and get a tangible record of the work done.

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## Smergen

A little milestone last night, with all the posts in and accounted for. Just in time also with a bit of drizzle and rain overnight. Will see how good a job I did over the next week while the cure but I'm reasonably confident that they will do the job. The Site Manager did an awesome job lining them up and they look nice and in line. 
Will spend the next week sorting out drain line, and possibly cutting the shorter lengths to size. 
Did take a few more shots, but left the camera in the shed. Hopefully later on tonight.

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## shauck

Looking forward to pics.  
Are you going to bolt each row or allow the natural forces of the back fill to hold the sleepers in place? (you can build the wall in one go and pin each row with a nail or wire or you can backfill each or a few rows as you go) 
If it's the latter, It's a good idea, as was suggested to me, to bolt the first row, level as then it can't settle and keeps your whole wall tied together and level in the long term. 
Much cheaper not having to buy all those bolts and less work too.

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## Smergen

Hey Su,
Downloaded the photos last night but didn't upload them to RF as I was too knackered! Will try and post them up tonight before I focus on my brothers wedding this weekend. 
In regards to the wall my intention is to bolt them all together to the posts to help prevent movement. I've had all the bolts provided to me so there's no cost for me there, although not having to mark, measure, drill and tighten would save a lot of work. My intention also was to construct the whole wall and then back fill using the excavator over the back fence (should save a bit of time). 
But you are right, making sure the first row is level is going to be critical.

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## stevoh741

> Looking forward to pics.  
> Are you going to bolt each row or allow the natural forces of the back fill to hold the sleepers in place? (you can build the wall in one go and pin each row with a nail or wire or you can backfill each or a few rows as you go) 
> If it's the latter, It's a good idea, as was suggested to me, to bolt the first row, level as then it can't settle and keeps your whole wall tied together and level in the long term. 
> Much cheaper not having to buy all those bolts and less work too.

  I build a lot of retaining walls and IMHO nothing looks worse than a bunch of fixing heads on the front of the post sleeper. I use 200x75 h'wood posts and 200x50 h'wood rails and fix them through from the back into the post woth 100mm gal batton screws. Not a fan of the pine and the 30-40yr guarantee is a crock. I put some treated pine sleepers down 2 years ago at the bottom of a fence then recently pulled them up and over half of them were rotton through. What was left of them just crumbled in my hands. If I have no choice but to use pine, I smother the in-ground bit in CN Emulsion and the exposed faces with CN oil.

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## shauck

It's not recommended to use an excavator to back fill a retaining wall so be very careful. Dumping a load of back fill all at once may cause damage. Go real slow with that if you decide to do it so as not to undo your good work.

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## Smergen

Some good tips there guys, thanks very much. Not to fussed about seeing the bolt heads, the wall is out the back and out of the way. Plus I have them and aren't spending more on the wall  :Smilie:  
Good point as well Su. Maybe I'll just get him to dump it at the back fence and I'll shovel it over so as not to put too much impact load on it.

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## Smergen

Some random shots of the final posts going in last week. 
The site is again a mud mine, but at least there are no deep puddles. Hopefully site tidy up this week, and start with the wales...

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## Roadhouse

Hey mate - just read the thread and appreciate hearing what you're going through. A good read and really makes you think about all the little issues that can crop up.  
I am about to embark on my wall - approx 15m x 0.7m, with the added joy of it being on a boundary. Read heaps on here and elsewhere about what to do and have planned meticulously (perhaps that's why it is 9 months down the track and I haven't started yet  :Tongue: ) but very keen to get started! 
Will be following your thread with much interest over the next few weeks.  :2thumbsup:

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## Smergen

Thanks Roady... yeah the wall will probably drag out for quite a while with a holiday imminent for 3 weeks. But I'm glad I've started, gives you a project and each time you do something you look back and go "yep, done that". 
Tonight will be site clean up after the rain and I'll work out exactly how I'll drain the bugger. Not sure I'll get onto digging with another 50mm due later this week, but I want to plan out the wales and get started on the cutting of angles, which I'm sure will be great fun... 
Will continue the updates though for sure. Like you said, learnt a heap from this website so if I can give back, even through my mistakes and people learn something, then that's sweet with me.

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## shauck

Hey Smergen. 
What's happening? Taking a break? Just wondering how your wall's going.

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## Smergen

> Hey Smergen. 
> What's happening? Taking a break? Just wondering how your wall's going.

  Hi Su, sorry I've been off on holidays so the wall is still in limbo. Actually, it's just a bunch of posts! So I'm hoping to get cracking on them again soon!

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## shauck

Good to know you're still alive.

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## Smergen

Easter weekend... is it possible... I might get some work done on my 'wall'. I hope so...

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## Smergen

Well.. who would have thought it. It's back up and running. The first two base wales are down and bolted in. Nice and level, but a little skew at the join. I'll put it down to variations in the sleepers  :Smilie:  
Hopefully get the bottom level down tomorrow, which is the hard part I believe. 
By the way, anyone know a good way to chip and level some concrete?

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## Smergen

Well, progress has been made. 
It has been a ripper of a long weekend weather wise, and with no holidays or trips planned, I intended to get stuck back into my 'wall' which had seen litle progress over the past few months. It was almost looking like my own 'Sleeper-henge' with the posts just standing around doing nothing... 
So I had set myself a challenge of getting the bottom row down over the weekend. Doesn't sound too hard, but with the Managing Director out of action with a knee reco, the two Site Engineers had the run of the land. So distractions were frequent and often... 
But... I can confirm... that I made it. First row down and I'm pretty happy. It's probably not to my OCD-like precision but I soon found after swapping and manipulating these sleepers that none are identical, none are exactly the same lengths and a few had gone slightly askew in the shed. 
But in the end, I just decided to get it done so that it would work. If it was a 'show' wall, i.e. not stuck out the back of the shed where it will never be seen. So where I thought I'd start looking through the pile of the sleepers for the 'best' looking, when you are moving them around dodging 3 and 1yr olds, you just take the next one on the top...  :Biggrin:  
So plenty of lessons learnt and quite a few questions raised on where to from here...  (they'll come later - and possibly from a few posters I hope...). 
I should point out that the second row you see in the shots aren't bolted in. They were just sitting around and I thought I'd check to see how they fit and levelled out in prep for the next weeks work. I'm quietly pleased. Not bad for a pencil pusher...

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## shauck

Yay! You must be pleased. You may find not all the sleepers are the same width. I found this with mine. So by the time I got to the top of my wall some sections are slightly higher and others lower. I could have left some out and exchanged them and be really particular but like you I just wanted it done. Mine is on show though but oh well, good enough.

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## Smergen

> Yay! You must be pleased. You may find not all the sleepers are the same width. I found this with mine. So by the time I got to the top of my wall some sections are slightly higher and others lower. I could have left some out and exchanged them and be really particular but like you I just wanted it done. Mine is on show though but oh well, good enough.

  Thanks Su. Yeah, I don't think I'm going to get to precise on the wall from here on. I'll put the level on each wale and make sure it isn't too far off, but otherwise, let's just get cracking and get it done I say.  
I do have some questions I hope you or another forum-ite might help me out with: 
1) You mentioned not bolting them in from here. Is there a particular reason? I realise that the wall will exert pressure and pin them to the columns but I was thinking one or two on each end will help keep it in place. The clay around here seems to expand and contract quite a bit so I was thinking it may also help with that.
2) As you can see the bottom wale sits above the ground at the moment. My initial intention was to sit it fast on the clay but the concrete surrounds of the post put pay to that. Now in regards to my drainage, I'll put the agi pipe lower than the wood, but should I put my scoria drainage underneath the wood or compact some clay/conrete in there? The finished level will be an inch or two up above the base of the bottom wale.
3) Also, where I have an angle joint, I haven't flushed them up, but simply sat the edges of the sleepers against each other. Not particularly proud of this finish, but it was once again a case of time and energy. I'm now wondering what I do to this 'joint' to stabilise it or at least seal it up a bit.
4) I'll be putting geofabric down around the agi pipe, but would simple black plastic on the back of the wall be suitable to stop water leaking through over time? Is it required? Overkill?
5) The scoria backfill... How much do I use and should I go the entire height of the wall?
6) The existing wall - I'm pretty certain I'll just leave most of it in place. I might take a few more off the top runs but the rest can just assist reducing load on the new wall. I imagine once it is fully buried the rot process will certainly speed up! 
OK, they are just some of my current thoughts/quandries. Any help is greatly appreciated. 
But I'm just stoked it's back up and running!

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## shauck

I'm no expert. Just my own experiences... 
1. Best reason I can think of is less work. Yes the back fill will keep the sleepers in place. You can put in a couple of rows and back fill as you go. As your back fill is scoria, it will keep the clay from pushing on the wall, a buffer sort of. 
2. I tried to make sure the concrete was not filled too high but had similar problem with a couple of posts. This also made it hard to get the agi pipe lower than the bottom row and to the correct fall. Have a good look at this before you dig that trench. I ended up knocking a bit off the top of the concrete to get past it.  Get the ground level up to the front of the sleeper to block the gap and then put your scoria behind/under it. I would have thought scoria under the sleeper is better than clay??  
3. If you haven't already cut all your sleepers to length, cut one and put in place then place the other without having cut to length yet. If the gap is noticeable, get a bevel and check the angle, transfer that angle to the other sleeper and hopefully get a tighter fit. Geofabric behind will help keep silt from coming through. 
4. Use geofabric not plastic, especially if your wall is a bit gappy, ie at the join. The wall is supposed to allow some moisture out otherwise you might be creating a dam with plastic. The geofabric helps stop silt and so on but allows moisture out. 
5. Just fill the trench behind the wall and leave 100-200mm at the top for soil. I forget the correct width of the scoria trench. A few hundred mm?? My trench had some collapse before I could get the wall up due to heavy rain back then so it was pretty wide in places. That meant a lot more scoria. Some of your trench is pretty big too. Oh well... 
6. Yeah, I'd leave most of it there. You'll just have more scoria to backfill if you take it all down.  
Having said that, I wonder if it is a problem later after it rots away. Could it leave space for movement of the ground towards your wall?? I hope someone can answer this one.  
Cheers, Su.

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## Smergen

> I'm no expert. Just my own experiences...

  And your experiences are far better than my guesses Su...  :Smilie:    

> 1. Best reason I can think of is less work. Yes the back fill will keep the sleepers in place. You can put in a couple of rows and back fill as you go. As your back fill is scoria, it will keep the clay from pushing on the wall, a buffer sort of.

  Fair point, but I reckon I might keep bolting them in until I run out of bolts! I kind of want to get most of the wall built (i.e. up 4 or 5 wales) before I start backfilling, and I'd be worried the big sleepers might make their way down onto me otherwise!   

> 2. I tried to make sure the concrete was not filled too high but had similar problem with a couple of posts. This also made it hard to get the agi pipe lower than the bottom row and to the correct fall. Have a good look at this before you dig that trench. I ended up knocking a bit off the top of the concrete to get past it. Get the ground level up to the front of the sleeper to block the gap and then put your scoria behind/under it. I would have thought scoria under the sleeper is better than clay??

  I dug the trench out a bit more yesterday and will check it's fall and grade tomorrow morning before putting down the agi pipe and first course of scoria. I'll certainly put scoria under the sleepers where appropriate though I think. Like you said, better than clay and should keep moisture as much as possible away from the wood.   

> 3. If you haven't already cut all your sleepers to length, cut one and put in place then place the other without having cut to length yet. If the gap is noticeable, get a bevel and check the angle, transfer that angle to the other sleeper and hopefully get a tighter fit. Geofabric behind will help keep silt from coming through.

  I may have confused you with this, but basically I sat the edge of the ends of sleepers together in a narrow 'V'. But I'm determined to rectify this though by cutting a sleeper to angle from tomorrow to ensure a flush joint. As for the bottom row I'll wedge and screw something in place to try and ensure the sleepers don't warp over time.   

> 4. Use geofabric not plastic, especially if your wall is a bit gappy, ie at the join. The wall is supposed to allow some moisture out otherwise you might be creating a dam with plastic. The geofabric helps stop silt and so on but allows moisture out.

  Makes perfect sense.   

> 5. Just fill the trench behind the wall and leave 100-200mm at the top for soil. I forget the correct width of the scoria trench. A few hundred mm?? My trench had some collapse before I could get the wall up due to heavy rain back then so it was pretty wide in places. That meant a lot more scoria. Some of your trench is pretty big too. Oh well...

  Well I've got a few cubic metres of the stuff but I also have quite a lot backfill required behind the wall. But I'll make sure the scoria extends most of the height of the wall. I'm hoping to score some back fill from the site behind us if the Site Manager has any left over (judging by the constant stream of trucks, I'd say that's a given...)   

> 6. Yeah, I'd leave most of it there. You'll just have more scoria to backfill if you take it all down.  
> Having said that, I wonder if it is a problem later after it rots away. Could it leave space for movement of the ground towards your wall?? I hope someone can answer this one.

  I'm going to remove as much as I feel is pratical whilst constructing the wall and not having the existing retained earth fall in (and bring the fence with it!). 
Looking forward to a productive weekend...

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## shauck

> Fair point, but I reckon I might keep bolting them in until I run out of bolts! I kind of want to get most of the wall built (i.e. up 4 or 5 wales) before I start backfilling, and I'd be worried the big sleepers might make their way down onto me otherwise!

  I reckon bolt the whole thing then. Just aesthetically it will look better if it's either all bolted or all not bolted (except the bottom row of course) You can sit 4-5 rows by just pinning the sleepers from the back with a nail into the posts, if you want. I didn't need to pin them as my posts were vertical and I did do about 4 rows before backfilling. You just have to make sure you don't get little scoria rocks stuck between the sleepers. Anyway, you've got the bolts so go for it. 
I think I get what you mean by the join now. It looks like it's an obtuse angle? Is it too obtuse an angle to run one sleeper behind the other and cut the other to fit? Hard to tell from the picture.  
Just one other thing, (too late for your bottom row, unless you can be bothered redoing it) try to cut the sleepers so joins fall behind a post rather than between them. In the third picture, the two posts on the right hand side have sleepers joining like this. It looks like a straight run so assuming that it is, you can hide the join behind one of either posts.

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## Smergen

Some more work done on the wall. Bottom few wales are down, and made a few end cuts to size. The wet weather and looking after the clan has slowed down progress but we're getting there. 
Su, yeah the angle is obtuse and I did just cut it so it fell behind it. I wish I'd done it with the first row now. Ahh well... Cutting was a pain also as the drop saw or circular saw didn't have a long enough blade to get through the sleeper at the angle I needed. So I did what I could and used the hand saw with the rest. 
In regards to having the join behind the sleepers, the plans and specs that I used off one of the links from here state span widths between posts so I kept them at that. I realise there will be a join between them but I'm not too worried. The 'overhang' isn't far in any of the spots and I doubt that there will be and deflection and bend at the joins. I might thrown a join plate across them if I get worried. To be honest, I just want this thing finished now so I can get on to the next job. 
Couldn't get hold of any geofabric anywhere in town or nearby. Bloke at garden supply place suggested using weed matting behind the wall. This will hopefully stop the soil but then let through the moisture. Thoughts? 
Many things I could do better, I've even done some things right. I'm reasonably happy how things are going...

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## shauck

Hand sawing...fun. Looking good. Bet your pleased it's all well under way. Don't stress on the geofabric. You don't have to use it. I don't know anything about weed matting. If you still want to get geofabric, there is a manufacturer that I found by googling it. They are Geofabrics Australasia.

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## Smergen

> Hand sawing...fun. Looking good. Bet your pleased it's all well under way. Don't stress on the geofabric. You don't have to use it. I don't know anything about weed matting. If you still want to get geofabric, there is a manufacturer that I found by googling it. They are Geofabrics Australasia.

  Yeah, I'm not too fussed by it. I reckon I'll be sweet just lining the face of the wall with the mat and be done with it. 
Very happy with the progress now it is up and running. If I could get a clear day at it without the rugrats I reckon I'd just about have it done by now. Each wales only takes 10-15, to drill and bolt in. And I started cutting end pieces last night in the shed while it was raining. Was happy with it. It's like a jigsaw and I've just about got all the pieces there. Just need the rain to stop!

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## Smergen

Another fruitful and productive weekend. Have the drain down, and scoria backfilled all the way around the wall up to about 2 or 3 sleepers high. Would have kept going but I ran out of materials! So then kept going putting the wall together and is now up to 5 sleepers high in spots. Hopefully going to source some top soil and scoria this week and get this thing dusted this week, weather prevailing. 
Photos to come.

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## Smergen

Alright, can't believe it. After so many months, so many rain delays, I think I'm just about done... 
All the wales done, the best part of the drainage/scoria done and only awaiting some backfill to 'fill in the gaps'. 
Doesn't look too bad if I do say so myself. There are plenty of things I could have done better, or would do differently. But most of the problems I found were brought on by the incosisteny of wood. 
But really I've loved the challenge, the frustrations and the sense of accomplishment. Really looking forward to finishing the job and putting the finishing touches. One last problem as to how to put the 'small end' together and tie it in with the existing wall. 
Here's some shots...

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## shauck

Fantastic. Great job. Hard to tell from the pics about how to tie in to the old wall but you may have to put a post in, in line with your new wall end/post, hard up against your old wall and run short wales between them. Then a post hard up against the fence and run wales from new wall end/post to that. I may be seeing it wrong though. Anyway, Good on you for getting it done.

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## Smergen

Thanks Su. My plan is to put one of the old sleeps flat up against the existing wall and use that as a post. Will dig it down a little and possible use some quick set concrete to give it a base. That should give me enough to work with I think to fix the end in. It won't be hold much weight any how that end so hope that will work. 
How are you projects going? Slowed down over winter or too busy to post?

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## shauck

Sounds like you've got it sorted. I am pretty busy at the moment. All my time is directed towards building a 10x5m bush house with a u shaped mezzanine floor with a 45 deg pitched roof. It's almost all I think about. I wake up thinking about it. So far i'm up to the joists, which I'll finish today. I've been on site for about a week so far and am trying to get it done as quickly as possible so that some local guys can get the tin on the roof before they go away up north. I really don't fancy standing on a 45 deg pitch roof frame. I should probably do a post on it. It's my first complete house, on my own. In fact it's my only complete house build apart from the transportable we made in Pre-app (carpentry). Bit of a challenge. When I finish, I'll get back to building my under-deck shed.

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## Smergen

Good to hear that you are at least keeping things ticking over. 
Here's a thought that I'd put out to the Renovate Forum crew - I've got a fair bit of decking oil left over in a tin from previous house, that is just sitting collecting dust. Now I'm a fan of the redwood, but would there be any benefit in using the oil putting a light coat over the wall to help with preservation or is it just a waste? I'm not really fussed, but thought if (for some reason) it helped the wall, I'd be happy to do it. Just an after thought.

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## shauck

I believe it's supposed to help with longevity, cracking, etc.

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## Smergen

OK, the ends have been tied off, the wall has had backfill tipped in and all that is left is to even it out and tidy up the 'site'. I've taken some shots, but I'll wait until I've done the final clean up so we can get some nice 'before and after' shots. 
Haven't got around to oiling the wall either, so that may need to be done if I think it will be worth while.

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## Smergen

Lattice up on the fence and a couple of passionfruits planted to climb around on top of the wall and green up the corner. Just need to get rid of some of the old junk, then I can bring in the Tuscan mix to cover the bottom and we're just about done. Need to sort the drainage channel down the side of the shed also. We're in two minds about asphalting the hard standing areas surrounding the shed so we will wait until we decide what we're doing there before finalising drainage... 
Have noticed interestingly that timber has shrunk a bit as it dries out. As I've bolted each row in, it's created small gaps between each wale in places. Nothing critical as I've got the weed matting behind the wall, but just something I noticed. I suppose if you don't bolt them in, they move around naturally. 
Photos coming soon...

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## shauck

Yeah. Mine show a few small gaps from shrinkage here and there but it doesn't seem to matter. Only bolted bottom row.

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## Smergen

Just awaiting the mulch and crushed rock for the ground and we'll be done. Oh, and for the climbers to do their thing...

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## Smergen

Mulch....

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## shauck

lookin good

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