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Damp Proofing

Tanking + renovation plaster

Anonymous user 28/02/2024 - 3.41 PM

Hi all, Need some help and advice from you kind people please! I recently decided to undertake a renovation project for myself namely making our cellar a useable space... I am using tanking slurry to waterproof the walls and floor as well as sealing wall/floor joints and holes etc. Also planning to use self levelling compound for the floor to get a nice level surface. My questions are as follows as i can't seem to find information on these: 1. Do i need to add some sort of limelite renovation plaster to the tanking when complete or can i just leave the slurry to dry and use the cellar as is (will the tanking slurry be enough without the plaster to make the cellar a useable space without getting damp come in)? 2. If i do need to apply the renovation plaster, can i paint straight on to the renovation plaster when dry or do i need to apply another finish plaster on top and then paint that? 3. Best way of waterproofing/sealing screw holes in the wall (needing to attach some wooden supports to the walls for the floor above but don't want damp coming through the holes). Someone suggested injecting the holes with silicone sealant and then putting the screws in as normal? Any help would be much appreciated.

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2 Answers

MJH Damp Surveyors

Rating: 5 out of 5

Luton

Hi please find some information below. Waterproofing Your Cellar: Tanking: Recommended For Dry Storage Only: Waterproofing below ground level is often referred to as ‘tanking’ — the application of a layer of waterproof material directly to the structure. This is usually a cementitious waterproof 3 coat render system and a Gypsum skim coat on the walls linked to a waterproof screed on the floor. Tanking can also involve a sheet membrane, asphalt or other liquid-applied waterproofing material. Tanking is also required to withstand the external water pressure around the cellar (hydrostatic pressure). The pressure from the water table around a basement can be enormous and unless the tanking is very securely fixed to the substrate, it can fail. Hydrostatic pressure will force water through the tiniest fault very rapidly and once a leak occurs it can be very difficult to isolate and repair: Cavity Membranes: Habitable Area: Cavity drain membranes are an alternative. The membranes are used to create an inner waterproof structure in the basement or cellar, behind which is a cavity (created by the membranes studded profile) that is fully drained, so any tiny leaks in the outer structure are diverted harmlessly away via a drain. By constantly draining away any small leaks there is never any water pressure against the inner structure. Several reports consider cavity membranes to be the most reliable way to waterproof a basement. Hope this helps.

Answered19 November 2018

DAMPTECH SOLUTIONS

Rating: 5 out of 5

Weston Super Mare

There needs to be layers of sand cement built on top of tanked walls once it’s totally dry 2-3 coats before a final plaster coat allowing adequate time for all to dry . Leaving just the tanking exoposed wouldn’t look great plus if left any moisture will be dripping down the walls as it’s stops and water penetration coming in but also has the same effect as it stops and moisture getting out so adequate ventilation is a must . Also I try to tel customers to avoid prior investigation the waterproof layer but if they have too then pump a lot of waterproof silicone in any holes drilled ... I have jobs 4+5 yearsxold thst customers have done this and no problems to report . Hope this helps

Answered21 November 2018