# Forum Home Renovation Decking  Finer details of screwing your deck

## BrissyBrew

Information from other threads to date: *SCREW TYPE*
10g type 17 square drive countersunk stainless wood screws 50mm
But I'd go for 60mm  *No trim heads*
Trim heads will pull through the board eventually if it wants to move bad enough  *TOOLS*
The best tool for fitting the screws is a cordless impact driver
The proper 10Gauge screw will need a 1/8 pilot and 10g countersink, checkout all in one options.  *METHOD*
With the Stainless Steel screws you would definitely have to pre drill both the deck boards and the joists (if the joists are hardwood).
I'm using a compound drill bit to drill the pilot hole and countersink in one go.
I did some dry runs beforehand: as you say, pre-drilling is a must and the diameter, driver speed and clutch settings are critical for the SS screws which are brittle and snap easily when hot. Make sure the driver is fully inserted into the screw otherwise it ruins the head. Make sure you use a drill with clutch. I have a Hitachi and used the highest clutch setting.
Screw slowly
Use 2 holes per joist and offset them to prevent the joist splitting
Lubricate the screws before hand, dont use detergent, linseed oil, too much could interfere with surface finish later  *ISSUES*
If you're using stainless screws (recommended), you've got to watch out
for stripping the heads. A driver with a torque control is essential. You
might also need to withdraw the screw, clear the type-17 tip, and re-insert.
Even better, if you can find gal screws of the same gauge and thread pitch,
you can use one of these to cut the thread path, then withdraw it and
insert a stainless screw. That way, the tougher gal screw is doing the
hard work and if its head gradually strips, just chuck it out and use
another. This strategy only works if the thread pitch (turns per inch)
is exactly the same on both types of screw.  *SUPPLIERS* *Screws*
Best Quality Screws as recommended by utemad http://www.macsim.com.au
Macsim no. 17sscb1050 10 - 12 x 50mm 304 stainless
Ebay supplier http://stores.ebay.com.au/ChloeFasteners http://www.tradeproducts.com.au/10g_...,_square_drive,  *Countersink Tools/combos*
countersink we use is made by carbi-tool and cost about 45 bucks
model no...DCS 3.2 which obviously stands for drill-countersink-3.2mm
DECKING MATE Countersinks & PreDrills in 1 Manouvre 10g http://cgi.ebay.com.au/ws/eBayISAPI....DER:SIMPLEITEM   *QUESTIONS*
I need to replace old decking on my front veranda, but dont want to have to replace the joists as they are still ok, although they do have a little surface splitting along nail line, hence why I decided to screw the decking. Would it be advisable then to use longer screws say 60mm. Will I need to also pre-drill the hardwood (seasoned) joists, if so do the all in one counter sinks come with longer pilot drill bits.

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## Dusty

The best way to screw a deck...................Hire the wrong god damn tradesmen to build it. :Hahaha:   
Seriously, excellent post. The info you've gathered and placed in one place will be of great help to others. :2thumbsup:

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## UteMad

old hwd  joists i wouldn't bother  they are too hard.. thats me though 
cheers utemad

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## BrissyBrew

> old hwd joists i wouldn't bother they are too hard.. thats me though 
> cheers utemad

   Hi UteMad 
When say you wouldn't bother they are too hard..  are you referring to: 65mm screws, that is the old seasoned joists will be as hard a nails so 50mm is fine. orI may be better off nailing the decking because the old joists will be too hard and I will spend all my time ripping the heads of the screws.I am concerned with a small amount of rot at the end of a couple of joists (about 5mm deep in parts just at the end) but really wanted to avoid having to replace the joists. I have been considering using some timber restoration/hardner and or running a second joist next to my existing joists and bolting them together. The current joists are housed inside the bearer to provide slop. 
I have also been thinking of putting a hardwood/pine fascia on maybe thicker than normal and bolt this to the bearer and rest on the front stumps, to help firm things up. It would also ensure that the decking around the edge which will overlap by 10mm or so will be resting on something solid. 
Timber for the decking I am considering Qld Spotted Gum. I have decided to steer clear of exports to try and keep the house with its original queenslander character (although screwing the deck does go against this mantra).

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## fdip

What are your thoughts Utemad re screwing in 140mm deckboards in a straight line or staggering the screws to avoid the joist splitting?  
Will this occur even if you have used a predrill/countersink bit like the Carbitool? 
Or is this more prone to happen on a 70mm or 90mm board as the screws are closer together? 
Har far in would you recommend screwing on a 140mm board - 25-30mm? 
Cheers

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## UteMad

> What are your thoughts Utemad re screwing in 140mm deckboards in a straight line or staggering the screws to avoid the joist splitting?  
> Will this occur even if you have used a predrill/countersink bit like the Carbitool? 
> Or is this more prone to happen on a 70mm or 90mm board as the screws are closer together? 
> Har far in would you recommend screwing on a 140mm board - 25-30mm? 
> Cheers

  
Old hwd as in joists get harder as the moisture it was delivered with wet disappears with time ( years ) if you try to screw into old hard wood joists you will most likely end up back here like most do complaining of snapped screws all over the place and have someone tell you to pilot hole the joist for every screw.. 
If the joists are pine i have never had an issue even with 90mm decking of getting a centre split in the joist like the old hardwood joists did.. like i said above the old hwd joist were delivered wet and supple so they could take the nail being driven straight into them when new . as they dry and become less supple they split under strain and let water into the crack and wrot the top of the joist out in a V shape.. This is why and under floor inspection cant pick it up til the boards are removed and why all our reboard quotes have a clause attached .. No joist can be declared good til the boards are removed .. 
slightly off track towards the end hehehehe  
Carbitool is designed to pilot only the board and not the joist.. This is what the drill gauge is set for.. smart bit is a lesser quality built but better tool now for DIY as it has auto depth set. We have a commercial grade version of the smart bit we run at 5 times the price but they work a treat.. Still own carbitool just the others are better especially when not used by an experienced person giving a far more consistant result 
Around 30mm is finein from the edge . if using 10 or 12G screw if using bugel batten 14G then you may need to come in 35mm to allow for head size 
cheers utemad

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## BrissyBrew

> Old hwd as in joists get harder as the moisture it was delivered with wet disappears with time ( years ) if you try to screw into old hard wood joists you will most likely end up back here like most do complaining of snapped screws all over the place and have someone tell you to pilot hole the joist for every screw.. 
> If the joists are pine i have never had an issue even with 90mm decking of getting a centre split in the joist like the old hardwood joists did.. like i said above the old hwd joist were delivered wet and supple so they could take the nail being driven straight into them when new . as they dry and become less supple they split under strain and let water into the crack and wrot the top of the joist out in a V shape.. This is why and under floor inspection cant pick it up til the boards are removed and why all our reboard quotes have a clause attached .. No joist can be declared good til the boards are removed .. 
> slightly off track towards the end hehehehe  
> Carbitool is designed to pilot only the board and not the joist.. This is what the drill gauge is set for.. smart bit is a lesser quality built but better tool now for DIY as it has auto depth set. We have a commercial grade version of the smart bit we run at 5 times the price but they work a treat.. Still own carbitool just the others are better especially when not used by an experienced person giving a far more consistant result 
> Around 30mm is finein from the edge . if using 10 or 12G screw if using bugel batten 14G then you may need to come in 35mm to allow for head size 
> cheers utemad

  UteMad from what I understand screwing my deck maybe a no no because of the old hardwood joists. Is this correct? Or does it mean that I will have to predrill once with the smart bit and pre-drill a second time with a longer bit to drill the joist. 
Am I just better off trying to predril and nail it because of the old joists. 
Or more to the point are you trying to point out I am wasting my time with the old joists because they will as hard as nails I should replace them? 
Thanks for your comments sorry if I am still somewhat confused. Prefer to learn from others experience if I can  
Edit:
After much thought I have decided to replace the bearers and joists, the cost is minimal and I will not have fix it again for years to come.

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## UteMad

Edit:
After much thought I have decided to replace the bearers and joists, the cost is minimal and I will not have fix it again for years to come.[/quote]  
Thats the right conclusion to come to.. we try to explain that to customers all the time.. If your doing the work the last thing you want to do is to come back in 12 months when a joist rots out cause then all you can do is a bandaid repair or the whole job again.. If new joists are going in i gather your doing pine with 50mm s/s screws ( assuming 18mm thick boards )  
cheers utemad

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## BrissyBrew

F17 hardwood joists, 100x50 as they are 2200 long.

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## Marc

On the topic of SS screws, I prefer 12G over 10G. Looking for a good deal I came across this site in the US. I was taken aback by the price. 
Have a look at this:  $286 US for  abox of 500, 12G 60mm can they be that much better than the cheneese we buy on e-bay for a third of that price? It says they are coated so I guess no broken heads, but still  :Doh:

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## UteMad

Trick with s/s screw is to buy true 10G or 10-12G and not 8-10G which only have 8G shaft like a chipboard screw but the same head size.. these are always cheaper and marketed by a lot as 10G ..  
Are the ones your looking at in the US 316 Grade?  Ours over  the counter are  304 or i have seen the cheaper saying  302 which is a lesser grade again?  316 here is a signifigant leap in cost.. 304 goes around 160 bucks per thousand as a guide and add another hundred atleast to jump to 316 grade 
S/S screws are going up in price of late especially for the better ones.. 
cheers utemad

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## UteMad

> F17 hardwood joists, 100x50 as they are 2200 long.

  
Have to leave it to those who do it more often.. from a business point of view we only use Tpine joist and if for fire reasons we use Merbau or similar then we tend to hand nail instead of screwing .. 
cheers utemad

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## BrissyBrew

> Have to leave it to those who do it more often.. from a business point of view we only use Tpine joist and if for fire reasons we use Merbau or similar then we tend to hand nail instead of screwing .. 
> cheers utemad

  for the span of 2200 and limited by max height of 100mm, I am stick with hardwood joists to span the distance.

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## UteMad

Or do like we would do and get 140's in treated pine and check them over the bearer.. not a fan of hwd joists as unless its good dar stuff there are too many irregularities in the stuff i have gotten in the past.. granted if sawn it just  sawn f11 gear but the 140's will be cheaper and easier to deal with..  
cheers utemad

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## BrissyBrew

> Or do like we would do and get 140's in treated pine and check them over the bearer.. not a fan of hwd joists as unless its good dar stuff there are too many irregularities in the stuff i have gotten in the past.. granted if sawn it just sawn f11 gear but the 140's will be cheaper and easier to deal with..  
> cheers utemad

   will checking weaken the load capacity of the joist, just that I know I am pushing the span at 2200. Although I have been considering 400 centres.

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## Marc

> Are the ones your looking at in the US 316 Grade?  Ours over  the counter are  304 or i have seen the cheaper saying  302 which is a lesser grade again?  316 here is a signifigant leap in cost.. 304 goes around 160 bucks per thousand as a guide and add another hundred atleast to jump to 316 grade

  Yes, they are 316. An overkill since 304 is more tha adequate, in fact I wonder why they don't make them from the cheaper (and stronger) 410. Probably not as easy to machine. 
Still if you say 160+100 per 1000 in 316 it is still a lot cheaper than $400 (au) per 500
There is not much supply of 12g though. Mostly 10g or 14g in Australia. Any reason?

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## BrissyBrew

> Yes, they are 316. An overkill since 304 is more tha adequate, in fact I wonder why they don't make them from the cheaper (and stronger) 410. Probably not as easy to machine. 
> Still if you say 160+100 per 1000 in 316 it is still a lot cheaper than $400 (au) per 500
> There is not much supply of 12g though. Mostly 10g or 14g in Australia. Any reason?

   400 series stainless or some cheaper still 200 series stainless are a PITA to machine, and people are familiar with 315 and 304 grades. But for screws you would have thought greater strength would be a winner. Same goes for stainless steel nails.

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## fdip

Hey Utemad another query for you. 
I am just finishing off the little fiddly bits on my deck and the end of the 140mm wide boards run a further 95mm past my last joist (450mm centres) to the framing boards. Do I need to fix more screws 30mm in from the ends or not? It will look very busy on one end with screws only 65mm apart. See pic.

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## fdip

Bump, anybody with ideas? See previous post. 
Thanks

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## Bain

> Hey Utemad another query for you. 
> I am just finishing off the little fiddly bits on my deck and the end of the 140mm wide boards run a further 95mm past my last joist (450mm centres) to the framing boards. Do I need to fix more screws 30mm in from the ends or not? It will look very busy on one end with screws only 65mm apart. See pic.

  Im in the same boat as you with this and would be interested to know whether there will be any cupping later on down the track. 
I have a feeling it should be fine..

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## UteMad

> Bump, anybody with ideas? See previous post. 
> Thanks

  
Nah they'l carry that distance.. my question is.... What size gap did you leave between the boards????? looks almost non existant like a little tile spacer at best  
cheers utemad

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## fdip

Thanks Utemad, just needed some reassurance. Yes, I used 3mm tile spacers throughout. I laid 4 boards at a time, the last board you see without the tile spacers was just in place to hold a join in place. 
Cheers 
Frank

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## Drewfus

Great thread. 
1) In regards to the Stainless variety's, whilst I understand there are huge variations in price from type to type (eg 304 vs 316), bang-for-buck, is there really any merit going for the 316 over 304 for the same size screw? 
2) On a slight tangent, the 90mm boards are more common (x19 thick), but if you were to go for a 140mm board (x 25mm thick), would you step up from a 10 gauge SS screw to a 12 or 14? 
Note: lets use the common merbau as the wood of choice for example sake 
Thanks, 
Drewfus

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## ScroozAdmin

> 1) In regards to the Stainless variety's, whilst I understand there are huge variations in price from type to type (eg 304 vs 316), bang-for-buck, is there really any merit going for the 316 over 304 for the same size screw?

  stainless grading can get pretty complex with many alloy options available, 304 & 316 are the common commercial grades. For comparison, the short version is 316 has more strength and better corrosion resistance, it basically has less carbon steel (which rusts) and more chromium and nickel (which doesn't).  
316 is found a lot in the marine industry and corrosive environments, if your near the coast, around a pool, using particularly corrosive timbers etc etc. then that's the way to go otherwise 304 is generally fine for most jobs.   

> 2) On a slight tangent, the 90mm boards are more common (x19 thick), but  if you were to go for a 140mm board (x 25mm thick), would you step up  from a 10 gauge SS screw to a 12 or 14?

  14g batten screws seem to be pretty popular for 140 boards.

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## samps

I'm looking at fixing 90x19 merbau into 90x45 MGP10 T/P joists using 10g 304 stainless countersunk screws. Where I have butt joins over the 45 wide joists, what is the recommended approach with regards to minimum distance from the edge of the decking board? If I screw 15mm from the edge that puts the screw very close to the outside of the joist (eg, 30mm centres leaving only 7-8mm each side). Do I need to nail another section of timber to achieve a double joist in this situation?

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## nodnods

> Hey Utemad another query for you. 
> I am just finishing off the little fiddly bits on my deck and the end of the 140mm wide boards run a further 95mm past my last joist (450mm centres) to the framing boards. Do I need to fix more screws 30mm in from the ends or not? It will look very busy on one end with screws only 65mm apart. See pic.

  Hi there, 
Your deck looks great - what is that protective strip on top of the joists, and where can I get it? 
Cheers,
Nodnods

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## samps

It's called protect-a-deck, available at most timber places and also the big green shed starting with B.

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## nodnods

Thanks a lot for the info samps. 
I'm about to start on a deck using the same materials as you described - I got 1500 10G x 50 304 SS square drive Hobson screws for $160 with free delivery from a place called the Stainless Store in Kirrawee in Sydney.  I ordered online late at night and they were couriered the next day.  On the same order I also bought a Starborn Smart-Bit pre-drill and countersink tool that came with 2 spare bits for $31.50 
My deck however is ony 2800 wide by 6200 long, so I shouldn't have to butt the boards together.  My challenge is to figure out how to support the joists over the 6200 where half is concrete slab from the back doors and the rest is over earth. 
Cheers,
Nodnods

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## stevoh741

> It's called protect-a-deck, available at most timber places and also the big green shed starting with B.

  Just inserting my 2 cents. That protect-a-deck IMO looks like cheap and nasty crap. It looks and feels like a hard plastic and I am sure that water would get down past the screw/nail penetrations leaving you with water trapped between the joist and plastic. Dont waste your money and go for a proven method using maltoid (a bituminous paper between your decking and joists. If you are really concerned (and anal) also paint the top of your joists with bitumous paint before laying the maltiod - also available at the before-mentioned shed and cheaper. I've seen 25yr old decks dismantled that had used maltoid and the joists still look as good as the day they were installed....

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## Bloss

The protecta-deck is fine and works too - this and other brands Joistrip - What does Joistrip offer? have all done formal testing and they perform well. They are very convenient since come in the correct sizes for joists and bearers. Malthoid (not maltoid) worked well for me for more than 30 years, and still works well, but when a new product comes along I try it and if it does a better job, or the same job, but saves time (=money), I'll change.

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## nodnods

Thanks very much Stevoh and Bloss, more options for me to consider!

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## ringtail

I dunno what proteck a deck youve been looking at stevoh, but it aint hard plastic, cheap or crap. Its soft ductile rubber with moulded wings, works great, works even better over the top of bitumen ormonoid.

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## stevoh741

> I dunno what proteck a deck youve been looking at stevoh, but it aint hard plastic, cheap or crap. Its soft ductile rubber with moulded wings, works great, works even better over the top of bitumen ormonoid.

  Your right it aint cheap - but malthoid (thnx for the spelling correction bloss) does the same job at a fraction of the cost. Also I have tried joist strip and apart from being friggin expensive it is a pain in the a$$ to put down. I have built heaps of decks and am willing to try any new product but ultimately when you do this for a living you want the best product for the best price. 
Anyone selling the stuff will tell you its the best thing since sliced bread but for me malthoid is proven and a fraction of the cost. The same with deck finishes - new ones come out all the time and each retailer will tell you it is the $hit. Well, I will give anything a go and I can tell you there is only a couple that live up to the makers claims. But each to their own and remember most things in the green shed come from China.....

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## ringtail

My timber supplier also sells a different version of the rubber joist protector. I cant remeber the name of it but its 3 x the $$ of protect a deck, is really thick and has several wings and mouldings. Looks flash, but hardly anyone uses it as it blows the job cost out the window. All I try to do is give my clients the best possible job for the right price, and for me, ormanoid with protecta deck does just fine.

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## nodnods

> Your right it aint cheap - but malthoid (thnx for the spelling correction bloss) does the same job at a fraction of the cost. Also I have tried joist strip and apart from being friggin expensive it is a pain in the a$$ to put down. I have built heaps of decks and am willing to try any new product but ultimately when you do this for a living you want the best product for the best price. 
> Anyone selling the stuff will tell you its the best thing since sliced bread but for me malthoid is proven and a fraction of the cost. The same with deck finishes - new ones come out all the time and each retailer will tell you it is the . Well, I will give anything a go and I can tell you there is only a couple that live up to the makers claims. But each to their own and remember most things in the green shed come from China.....

  Thanks Stevoh. 
Would you mind telling me what your recommendations are for deck finishes? 
cheers,
Nodnods

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## stevoh741

> Thanks Stevoh. 
> Would you mind telling me what your recommendations are for deck finishes? 
> cheers,
> Nodnods

  Each to their own but if you want an acrylic top coat spa and deck seems to last 18-24mths between coasts. Ultradeck is ok but NOT on spotted gum - I only use ultradeck on sleeper retaining walls (h'wood) and get 2-3 years between coats (horizontal surfaces would be more frequent).
However I have of late been going for the more architectural look of greying the decking (doesn't suit everyone's decks or tastes). However after initial cleaning with napisan and oxcyllic acid I use CUTEK preservative. This does a fantastic job and keeps the water beading on the deck well over a year. It also soaks in deep to the timber and stabilises it reducing cupping etc. Re-coat once a year with mop or brush on takes about the same amount of time as going to the local for a 6pack. (I don't like the lambswool applicators much as they tend to leave wool on the deck.
If you don't like the grey/aged look, cutek has colour additives (and quite a range) that when added will keep the colour in the timber. I haven't used a colour on a deck but have on vertical timber and recoat was about 2years.
Personally, I am over any acrylic or top coating decking finish (as most people dont keep the maintenance up and usually need to be sanded once degraded too far. After using cutek I don't bother with anything else. Heres the website: Features " Benefits of Cutek CD50<sup>®</sup>
Hope this helps,
cheers, steve

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## ringtail

That cutek looks pretty good, but I reckon mould would be an issue, like all decking oils that promise to be " mould resistant "  And spilt wine will give it grief as well, not that anyone spills wine on their deck eh ?? Is it well priced Steve ?

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## Bloss

> Each to their own

  Yep - and any brand really price is a good indicator - flat surfaces like decks have more extreme weather exposure (generally) as well as the foot traffic wear and so are a harsher demand on any coating. Many other threads will tell you what steveoh has said and what he says he does with Cutek is no different - highly exposed areas need a re-coat every 12-18mths (and as he says before any break down of the original coat is evident). Standard - prep is critical then maintenance - and the latter is where we nearly all fall down. Marketing claims should not be allowed to overtake your own observation - any sign of needing a re-coat, do a re-coat.

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## stevoh741

> That cutek looks pretty good, but I reckon mould would be an issue, like all decking oils that promise to be " mould resistant " And spilt wine will give it grief as well, not that anyone spills wine on their deck eh ?? Is it well priced Steve ?

  pretty standard compared to other brands - around $200 for 10litres. I usually do a mould prep before using any decking coating.

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## samps

Quick question on drill selection. I have square drive stainless screws into T/P joists and 90x19 merbau, and I've purchased a smart bit. I notice earlier in this thread there is mention of using a drill with a clutch. My 14.4v Metabo has variable torque settings and a pulse mode, would that do the job? It is not an impact driver as such.

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## r3nov8or

As long as you pre-drill it should do the job. Test on some scraps.

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## Poirot

On the question of malthoid vs others; Carter Holt has this good PDF out which actually recommends malthoid:  http://www.chhwoodproducts.com.au/us..._AUS_Aug08.pdf

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