Basement Tanking

[BruceyP]

Hi Guys

I'm looking to tank my basement. The house is a victorian mid terrace and the basement lies between my two neighbours basements. Presuming the levels of the neighboring basements are the same, need the party walls be tanked as there is just fresh air on the other side and no wet ground?

Obviously there is still a possibility of rising damp on the party walls but could a retro fitted dpc be fitted/injected to the base of the wall and up the sides of the party walls to stop water ingress travelling transversely from the two wet walls (front and back walls)?

I was planning on using dimpled membrane to tank the walls to the front and rear of the basement and floor but as both party walls are the longest sections it'd be great to save a bit of money by not tanking unnecessarily.

Also the other reason for doing this is on one party wall I have the bases of the chimney stacks that would look great as bare brick in the basement conversion. this would obviously not be possible if they were tanked in membrane.

Id be most grateful for anyones thoughts, ideas, problems and solutions.

Thanks guys.

 

[wavetrain]

How do you plan to drain the dimpled membrane system on the wet side?

also,

what is the floor area?
the party walls area?
and the remaining damp walls area?

 

[BruceyP]

I'll have a sump under the floor so the water can drain behind the membranes and the water will be pumped to drain.

The area of the floor is about 50m2 and,

The wet walls approx 12.5m2 each and,

The party walls approx 25m2 each.

 

[wavetrain]

retro fitted dpc be fitted/injected to the base of the wall and up the sides of the party walls

If you mean a 'proper' DPC then you will need permission from both parties to fit the horizontal ones across the 9" (guessing width) party walls. But for the vertical ones you would need tocut through the wall and this would break the bond between the party walls and the outside walls weakening the whole house structure I would believe ,so you cannot go this route.

As for an injected DPC, it is most unlikely to work well enough so forget that also.

Lastly, you wrote that there is fresh air on the other side. There is no such thing, there are basements which you have no idea or control over their moisture content. At some times of the year they may even be flooded.

Pay the extra few hundred pounds for the 50m2 worth of membrane and tank all walls as a sensible person would.

 

[BruceyP]

Well as for flooding that is not an issue as the houses are well above the water table (being on a hill) and i've had this verified. I understand the point about the condensate but would this really be enough to penetrate two courses of bricks and an inch of cement render?

To be honest the cost isnt so much of an issue but i'd really love to expose the bricks on the chimney breasts. Is there really no other options, solutions systems available?