Has anyone done/have experience of using a membrane system to tank a cellar?
It seems not to be a complicated process, but I haven't seen any details from someone who has done it themselves and appearances can be deceptive :)
As cellar converstion costs seem to run around the £40K mark, and I have a £20K budget, I'm thinking I could save a heavy amount by having the underpinning and floor lowering done by a contractor but doing the tanking and finishing myself.
Is this a viable route?
Could you define what you mean by a 'membrane system'?
The probs with a bonded membrane is that a high water drive can disbond the membrane from a weak substrate as is normally found in previously damp brickwork. Once it is disbonded water builds up behind and disaster results.
Look at cementitious waterproof coatings which will allow the substrate to breathe. There are several on the market. I sell one but am not going to advertise. Most can withstand about 20 metre head of water and can be, and in fact must be, applied to a damp substrate. They are applied by brush,roller or airless spray. They do not look very pretty but can be overclad, (do not pierce the coating for batten fixings).
There are Epoxy/Bitumen coatings available but a) They do not breathe and are OK for rearside applications (positive water pressure) and b) Bitumen smell seems to last forever. Same rule applies regarding fixings.
On 5 Jul 2006 08:59:32 -0700, a particular chimpanzee named "Bookworm" randomly hit the keyboard and produced:
Go on, say it. Vandex by any chance?
Wrong. There are about 6-10 manufacturers out there. I sell for one nobodys ever heard of and only sell to the trade. The poster would never be able to buy the product I sell even if I named it.
Just trying to impart some of my experience of selling Tanking Membranes and Tanking Coatings over the past 20 years.
Probably will be met with cyncism by some of the trolls who inhabit this group.
I was thinking about something like this from Newton Membranes:
So no-one could object to your naming it, then.
Owain
I have looked at the Newton Website and they quote:
'Newton Titan Sump and Pump to remove excess water that may enter from behind the sealed membrane system.'
I rest my case.
A 100% perfect way of tanking in such circumstances is what is called 'curtain injection' whereby holes are drilled at predetermined spacing through the wall and over the whole walls surface, to the outside substrate. An Acrylic Resin Gel is then injected at high pressure which form a waterproof curtain between the subsoil and the outside of the wall. Thus you are preventing the water from entering the walls in the first place.
It is very expensive and needs special pumps and experinced operatives. Being used worldwide to seal leaks in tunnels, CTRL, London Underground, Tunnel between Denmark & Sweden, Dublin Port Tunnel etc etc.
And then be flamed for advertising! Do me a favour? Address the guys problem or shut up. If you aint got nothing to say on the subject dont bother posting.
I am in the process of installing something very similar to the Newton system in my basement. I've used Wykamol since the sales guy was happy to sell to me as a non-qualified installer. They also sent an installation instructions CD which was pretty clear. By far the biggest problem is managing awkward shapes/corners etc. When it came to doing the floor I built a small cardboard model of the floor and cut strips of card to represent lengths of membrane and used this to work out all the overlaps, cut and fold lines etc. When laying it with my general constractor (no previous experience of the stuff) we used the model as a template. Only cut 1 bit wrong out of 60sqm.
I used it in a refurb where I was putting in a new floor and rather than use their perimeter drainage I installed perforated land-drains (with geotextile wrapped round to prevent clogging) running to a sump. Buy the sump pump separately as it's much cheaper and use something like a small cold water tank as the sump chamber.
In total cost of the membrane stuff came to =A3750 and it's a pretty big cellar, and an extra ~=A3150 for the sump pump and associated gubbins.
My cellar has rubble stone walls so the other problem was making successful fixings. As a result I hung it like curtains as less fixings required and will put up a stud wall inside this. If you've got brick walls it would go up like a dream and you can either use a version suitable for plastering directly onto, or fix battens to your 'plugs' and dry-line.
This is definitely a DIY job and suitable for almost all types of building (mines a listed Georgian townhouse). If you want further specific advice email is as presented.
Fash
Forgot to say I also did floor lowering but not by underpinning. Underpinning not a sensible option (for me) as walls are 600mm thick and rubble stone so liable to keep falling into any trench dug out for underpinning. If you don't need much height gain (I've gone from 6'3" to 6'8") then you can use a reinforced 'bathtub' floor where the reinforcing forms an upstand at the edge of the room, which when concreted forms a ring beam which holds back the earth at the base of the foundations. The whole floor needs to be reinforced to prevent any problems from heave lifting the middle of the floor.
I did all the digging out myself (with a little help from friends paid with beer), put in the under floor drainage, and had a contractor put in the sub-base and reinforced concrete, with a joint venture on the membrane as I wasn't confident they'd give it the same attention to detail that I would.
The other thing you need to consider is humidity as the membrane system works best when not fully sealed at the ceiling so you still need to deal with water vapour. I'm planning to put in a heat recovery ventilator which can deliver 4 air changes/hr but with the same heat loss as 1 change/hr. If this turns out not to be sufficient I'll add a wall-mounted dehumidifier.
Total conversion cost including drainage, contractor, a new RSJ across the room, stud walls, flooring (including undertile heating), lighting etc. is estimated at =A312-15k and gives me a room which is 19' x 13'.
If you want to share my ignorance further just ask.
Fash
On 6 Jul 2006 04:27:07 -0700, a particular chimpanzee named "Bookworm" randomly hit the keyboard and produced:
Perhaps it's good that you don't deal direct with the public.
You wouldn't be flamed by anyone worth worrying about. Your expertise would be helpful to many readers, myself included.
Sorry, I don't get what you mean here.
Thanks for the info. I'll email you for more details.
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