Damp proofing - what is 'Tanking'...

vansboy

Hi All!

Had the surveyors report on our 'upside down' house & he's concerned about the lower floor, which is partly below ground level, requires the concrete walls be damp proofed by tanking.

Never heard of it, so what's involved & does it work.

There's no real damp evident, currently.

Thanks in advance!

VB

benood

Tanking is basically a thick black tarry paint which you put onto the walls (and perhaps floor) before plastering to form an impermeable membrane against water.

Don't really understand why, if there's no evidence of damp, you need to do anything - but perhaps in the winter it will start to come through.

mistah

Tanking is basically a waterproof coating (e.g. Vandex) that can hold back water seeping in from the ground. Whether you need to tank the area really depends on what you are going to use the rooms for. Even if the walls don't look damp, they may be damp enough to affect and decorative finished (e.g. paint, wallpaper) that you want to put over them.

If the walls are still bare concrete, it is probably a fairly easy DIY job. You'll need to bush hammer the the concrete to remove any laitence and then just apply the Vandex by brush. If you need to do the floor as well you do it the same way.

iamcornholio

Tanking is a process of installing a barrier on underground walls and floors to keep the ground water out, and the inside dry.

It can be laid on ashphalt or bitumen, or it can be via more modern methods of a plastic impermeable barrier fixed on the wall and floor

There are other methods available, but the actual extenal ground conditions need to be known, and then the best solution specified.

Normally it is no good just coating the inside of a wall or floor, as the pentetrating water will blow the coating off.

never_enough

I had the bathroom done in a basement flat. It was hideously expensive & totally blew my budget. :eek: Was also a real pain for the bathroom fitter/plumber as you shouldn't puncture it to put up anything like shelves, blinds, towel rails, lights etc so he had to get everything really organised beforehand. There is something you can get to put into screwholes to sort of seal it, but check if it will invalidate your guarantee or not. It seemed to work, before that the plaster blew every 2 years or so, after that it lasted at least 6 years.
If there is no damp you need to speak to him to find out why he's suggesting it, as I said it's not cheap. He could just be over cautious, but you wont know til you speak to him.
Ventilation is important too, I had a very good extractor fitted at the same time as tenants seemed to have an allergy to fresh air.

mistah

Good point about not puncturing the tanking. You really have to think about where you want any shelves etc... before you do the tanking.