Sand/cement or bonding after tanking

17 Jun 2014
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United Kingdom
Hoping someone can help.
I have a wall (double skin cavity wall) that had damp. The damp problem has been fixed and the bricks are now dry. I have painted it with sand + cement tanking slurry with a waterproofer added. Can I get away with bonding and then skim? I’ve read somewhere that you then need to sand and cement render the wall but I’ve never done sand/cement rendering so would prefer to bond it out. If it’s been tanked, would bonding be sufficient?
Thanks all!
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You didn’t need to and shouldn’t add waterproofer to tanking....and can’t see why you tanked an internal cavity wall.
but anyway tanked walls are notoriously cold and prone to condensation which is why i’d rule out bonding directly. Also cement rendering over dry tanking is problematic as there’s very little suction . the most effective way is to coat it again with tanking and be ready to lay a thin scratch coat of render on when the tanking is just going off. lay a top sand/cement coat over following day. You should be good to bond or hardwall over that.
Hi @Godwasaplasterer, thank you. the roofer who did the remedial work recommended doing it as it was an older wall and due to their being a window there, to avoid damp coming through in the future. I still have the other room to do which hasn't been slurried yet. What would you recommend doing instead of slurrying the wall? just go straight onto the brick with sand and cement?
nothing wrong with tanking , only it’s usually a last resort and more often fixing the symptom not the cause. Did the roofer get to the actual cause of the damp ?. the fact that it’s an old wall should not make a difference providing the cavity is clear and dpc in tact.
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it was the guttering and the fascia, both of which have now been replaced, along with some slipped tiles. I don't envisage any further damp as the issue was obvious and has been sorted. The way he put it was that it (slurry) would protect the inside of the wall if there were any future damp issues as nothing will get through the slurry.
Can i just bond the other wall and slurry, sand and cement and bond the one that has already been slurried?

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