Cellar tanking

[CrazyFool]

Hi guys

I'm looking to renovate my basement.
I've had medium success at a previous property with using tanking slurry... it worked for the most part but there were two area where the tanking blew out. I presume because of the hydrostatic pressure in these parts, or maybe the brick was just not cleaned effectively enough.

What are my other options?
I don't want to install a sump pump as ideally I want a passive, maintenance free option.

How effective will DPM be along all walls and the floor?

Can I be sure that the water will simply be kept out and/or drain through the floor?

Instead of battening against the DPM to hold it in place, can I press PIR insulation against it and somehow fasten it in place? I intend on insulating either way and losing the battens means I don't need to worry about cold bridging.

Thanks in advance

 

[DAZB]

The best way is to do it properly with a tanking membrane etc but it could be done with visqueen if your intent is just to direct any moisture to the ground. The problem with that is you will invariably end up with a constantly damp floor which then affects the whole room. You can get plastic plugs with a gasket or seal on them from firms like Newton, PermaSeal, Platon and Safeguard and a quick google for "tanking plugs" will show them. The good thing about the plugs is that they accept a screw so designed for you to fix battens to for foil backed plasterboard or panels etc...You will also need to lap and tape every joint of the membrane with visqueen tape especially at corners or around obstacles which can be tricky. If you have any option of reaching a drain without a pump then worth cutting a recess around the perimeter and fitting some form of channel to direct any water to the drain. As that room has windows and a stone flag floor it will have been used historically as a habitable room, possibly a kitchen, laundry room or even for servants and would be a fair bet that there is a drain down there somewhere so have a look, maybe near the windows and lightwells externally and and also outside for the main runs that go below ground level.

 

[CrazyFool]

Thanks buddy.

I've had a look round for drains and I can't seem to find anything.
Will I have to lift the stone flags?
Any tell tale signs that might tip me off as to where I should start looking?

I'm thinking of a belt and braces approach... been reading up about adhesive membrane, I like this because the adhesive is a type of tanking slurry in and of itself, and the membrane provides further support.
If there is a way to discharge accumulated water that would really reassure me.

Thanks again

CF

 

[DAZB]

I would look around the wall for any old pipe exit holes and also the floor under the windows and even externally at the bottom of the lightwells as they may have a drain otherwise could fill with rainwater so a potential drain there. I have no experience of the adhesive membrane so can't comment on the effectiveness. As with most things though if you try to do it cheap you will probably end up doing it more than once.