rendering walls that have been cavity insulated

[puckoon]

hi all, I have to hack off defective rendering, then going to re-render, with waterproofing in the gauge. the walls have been cavity foam filled several years ago. will this have any adverse effect on drying out, or will it, could it, trap moisture and create damp inside.

 

[johniosaif]

External rendering ? Is this what you are hacking off,? Then you refer to damp inside,yes cavity filled walls if the cause a breech in the cavity and allow moisture to cross over then the will create dampness inside, best thing for external ,hack off, apply an sbr coat 2/1 with cement ,then another coat, scratch with sand cement 5/1 with waterproofer ,a week later float it with 6/1/1 sand cement and lime. I am not an expert re the insulation, someone else will advise more on this

 

[CTPlastering]

Seems good to me john , if the house has damp problems maybe try taking a few bricks out near bottom etc and see if cavity is full of **** they normally are .....