# Forum Home Renovation Structural Renovation  Building a cellar - brick, concrete or pre-cast walls

## prof_montoya

Hi, 
I'm planning to extend an existing house in Coburg, Melb. Adding 8x8mt room onto the back.  I'm thinking of building a cellar / basement below the extension (approx 5x5) to use as a cold storage room.  The 8x8 room will be on the boundary which is a laneway (south side). The cellar entrance needs to be be via stairs on the lane side/ south of room above.  The 8x8 mtr room will have solid slab floor.  My question is - should I build the cellar walls with bricks, poured concrete or pre cast concrete?  I'm thinking the soil will be backfilled right up to cellar walls therefore walls will need to be adequate to retain the soil and repel water/ moisture.  Appreciate your suggestions and maybe indication of costs between brick, precast concrete and poured concrete. 
Thanks
Monty (Carlos)

----------


## Moondog55

I am going to suggest you do a lot more research on this.
Water pressure ( hydrostatic and vapour pressure ) mean that there will be massive loads on the walls; think "Swimming pool" and you will need a sum and a big sump pump.
I like the idea of a cellar, some where cool to store the red wine and the spuds.
The walls need to be very well waterproofed, and black builders plastic isn't always the best product to do this so think "Expensive" the waterproof barrier needs to be protected ( more expense) then there needs to be a layer of crushed rock for drainage and aggie drain with silt sock laid under that ( even more expense)  and the walls need to be strong enough to support all that water weight, so usually reinforced water resistant concrete made to maximum specification and heavily reinforced.
This precludeds building the wall on the boundary as all work has to be done inside your property boundary and I don't think you can build a wall over back-fill

----------


## Ramoun

Basement/cellar is not to be taken lightly specially if next to a lane you never know what will be there.  If your on a narrow blcok the building next door can be an issue. 
I've been reserching this on and off for 18 months, looking at cast in situ walls crout filled blocks,  reinforcement, positive and negative waterproofing and tanking, best way to get added strength by adding beams across the top to stop the middle of the walls falling in. How to lay a slab while proping up walls and roofs etc. 
There are a few threads on this site that are worth reading. 
Good luck

----------


## Pulse

It is really just a retaining wall on 4 sides, the slab roof greatly reduces the strength of the wall since the wall is "propped" at the top. If you place the cellar away from the lane, the council will worry you less. The walls should be tanked on the outside with one of the many products available and then black plastic and fibre cement sheet to provide mechanical protection prior to backfill. 
good luck, this will help 
Pulse

----------


## prof_montoya

Thanks *Moondog*. Didnt realise there would be a problem building a wall over backfill.  Is this still the case if the above room (and wall) will be on slab?  If I go down the battered earth path on west, north and east side of the basement (non lane side) then how will this impact the above slab which is only expected to be 8x8.
Thanks *Ramoun*. So your preference is cast in situ. I've got to research "crout filled blocks and tanking". Thanks.  Is there any additive that waterproofs concrete?

----------


## PeteV

the only real issue, dependant on the depth of your pocket... is the boundary one. particularly with vehicular access directly above your hole. i can't see you getting that one over the line with council. Otherwise, i have built cellars out of block work and pre cast, and worked on jobs with insitu piers. All methods will work!

----------


## prof_montoya

Thanks *Pulse*. Thats right, all 4 walls basically retaining walls. If I need to "tank" on the outside then how much space would I need to allow for that type of work.  Is less than 1 mtr away from laneway sufficient to get in and do the work safely (and keep council happy)? PS I like the fibre cement sheet idea.  After all the 'tanking" work is complete do I still need a pump to remove any water that seeps and builds up around the outside

----------


## thetrooper

g'day prof  
personally id be sticking away from precast panels albeit they are a great product ( but im bias :Biggrin: )
some of the things you should think about are as follows.
cost of making panels
cost of transport 
cost of crane hire... big cranes (180ton) charge for the day  :Doh: 
site lay out... has to be mickey  mouse when talking panels 
site acess i.e is their over head power lines  etc etc 
some one with a riggers ticket ? 
you could also build your own panels on site but that is alot of work and would need a guru to sign of on it before you put the conc in 
hope this info has helped some what   
cheers
scott

----------


## PeteV

i'm with scott really, you're probably better off using bricks/blocks. blocks would probably be the better way, in a 290 wide series with N16 re-inforcement, probably 200mm centres horitontally and vertically. an engineer should be able to draw up something that will hold up. you can get waterproof additive for your concrete too. comes in either a liquid or powder form that you add to the truck when it rolls up.

----------


## Eastwing

Or use Dincell   http://www.dincelconstructionsystem....nstruction.pdf

----------


## thetrooper

> i'm with scott really, you're probably better off using bricks/blocks. blocks would probably be the better way, in a 290 wide series with N16 re-inforcement, probably 200mm centres horitontally and vertically. an engineer should be able to draw up something that will hold up. you can get waterproof additive for your concrete too. comes in either a liquid or powder form that you add to the truck when it rolls up.

  
Pete i have to agree but for the best part it would be easy to use heavy duty mesh to save time tying steel... as it is a pain in the ass if you have never doine it b4  
i steel fix every day and a project like this would take minimal time to run the nips over something like this  
1218 mesh on both wall sides would be a goer along with 16mm starter bars @400 centres (1200 x 1200 ) would make it more than structual i would think. 
whilst your their we might as well cast it in situ to make it fun ! :Yikes2:  :Yikes2:   
cheers 
scott

----------


## prof_montoya

Thanks Pete and Trooper.  So you're saying no pre cast panels.  And prob  best stick with brick or blocks.  In this case where does the  waterproof cement go?  Just in between the double brick / block walls?
PS do I still need to postive tank if i use the waterproof cement? Can i  get away without it? My concern is not having space on the laneway side  of the basement.  Also will there be any prob digging straight down or  do i need to slope sides?

----------


## PeteV

you will have to batter the sides for OH&S reasons. you will also still need to water proof with some sort of membrane. there are plenty of options with this sort of thing. another idea i saw done once which worked quite well was to dig trenches well below your floor level, drop cages in an fill it with concrete, use the dirt as form work... you then dig the middle out to 100mm below floor level and pour an infill slab. if your then worried about the finish you can render it. waterproofing then becomes an issue, but if it's only for storing wine in... not sure i'd be to concerned about a little bit of dampness, especially if you use waterproofing in the conc..

----------


## billbeee

Hi Guys,
You must consider the need for larger excavation for applying the waterproof membrane to the outside, so safety and all that. 
Besser blocks OK, cheap quick and easy. Lot of extra water proofing.  
Formed concrete fairly easy with hired panel formwork. Pour a kicker with the bottom slab and incorporate a water stop in the join to the walls, quite tricky. Again use a full external waterproof membrane. 
I would never consider bricks. 
I'll chuck in a couple more that I would definitely consider, but everything depends on the nature of the site. 
Tilt slab. Pour the base then stack cast the walls on site. Use water resistant additives and a high strength concrete mix.I would consider applying membrane on the flat before erection  and using PU sealer to joints. Depends on expected hydrostatic pressure. Would need smaller excavation. Tilt up or tilt slab  
Build it like a concrete swimming pool using Shotcrete or Gunite. The Gunite has fibre reinforcing but also you must use standard rebar. One day pour totally monolithic, apart from top slab of course.  Do stairs at the same time. Only excavate what you need. Minimal formwork. A  downside is the curved internal corners and it is a play off between strength and crack resistance and looks an amenity.  Shotcrete 
Cheers
Bill

----------


## thetrooper

xypex is a product used by boral to add in tghe mix 
and a product by hanson called 3cc  has a ver disdinct smell of cloudy amonia but safety gear must be used on both as usual !  
cheers
scott

----------


## prof_montoya

Thanks *Pete* - I thought this would be an OH&S issue! But not sure how to deal with it because have lane way on south side approx 1 mtr away and will have to fit in am 8x8 slab over the top.
Thanks *Eastwing* - I like dincel.  I've emailed them to get an idea of cost. Should provide waterproof solution without need for postive tanking.
Thanks *Billbeee* - will look into tilt-up and shotcrete. PS the dincel product looks like a good pour option. Wondering how much more it is than form work for in situ pour.

----------


## Bloss

I'd be looking at pre-cast solutions like these: Hytek Concrete Products - Wine Cellar
or this option: Hytek Concrete Products - Concrete Shelters and Amenity Blocks

----------


## Ramoun

Dincel looks good, It looks like it requires external piers to take most of the load after completion. 
I found doing a google search in photo's gave a 10 fold better responce than an average text search.  There were many section of basement walls,  there appears to be more adds for for negative tnaking insidethe basement which I suspect is a reflection of the waterproofing problems carrying forward from older buildingds. 
Searching on crawl space conversion gives some good info. 
Heres a couple of links I've collected you may find useful 
Good luck   YouTube - Waterproofing the foundation construction for the building of a house [ame=http://www.youtube.com/watch?v=3hd4C0UwA2c&feature=related]YouTube - Waterproofing the foundation construction for the building of a house[/ame]  Waterproofing Products and Services AMCOL Australia Waterproofing Products and Services AMCOL Australia  System Platon at Ace Waterproofing protects underground structures from backfill System Platon at Ace Waterproofing protects underground structures from backfill  http://www.bsa.qld.gov.au/SiteCollec...0Membranes.pdf  Drainage Do's and Don'ts Drainage Do's and Don'ts  http://www.waterproofmag.com/downloa...1_Drainage.pdf  http://www.wbdg.org/pdfs/edg/bg_124.pdf  http://materialsintheraw.com.au/medi...ing%20Wall.pdf

----------


## prof_montoya

Thanks *Bloss* - I've contacted Hytek. 4x5 mtr precast cellar (100% waterproof) without lid and stairs cost about $15. Add freight from Adelaide $6k and 100t crane hire $3k. All up $24k. Might be an option. Problems I forsee: 
1. Can get the truck down the side laneway (cobble stones).
2. Will the truck down laneway affect how close I can excavate. 
3. Crane access
Any idea if I can get a similar product in Melb/ Vic?

----------


## manofaus

How did you go?
ne reason you don't consider a underground concrete water tank? why such a big crane? if you have close access then a 40-50t would be ok?

----------


## jrckelley

I have seen this done using a precast concrete water tank before with a hole cut in the top and a ladder to get down. You'll just need to put some good drainage and a sump down first to ensure your room doesnt pop up through the house if you get a heap of rain. (Seen it happen - not funny). 
you could get a tank for $5k and a small crane or merlo for no more than $1000. rent a demo saw and cut your hole  - done

----------


## Oldsaltoz

> Thanks *Pulse*. Thats right, all 4 walls basically retaining walls. If I need to "tank" on the outside then how much space would I need to allow for that type of work.  Is less than 1 mtr away from laneway sufficient to get in and do the work safely (and keep council happy)? PS I like the fibre cement sheet idea.  After all the 'tanking" work is complete do I still need a pump to remove any water that seeps and builds up around the outside

  To waterproof the external wall, work on a minimum of 1m wide at the base, also have the geo sock drainage installed before waterproofing starts. The slab should be at least 100 mm wider than the base of all walls so the waterproofer can properly seal the wall to slab joint. Don't forget to line the floor with builders plastic before the slab is placed. 
Good luck.   :Smilie:

----------

