Dot & Dab Advice?

[jmd1994]

Hi so im new to this forum but have been a lurker for a while, just made an account for some advice

recently bought an early 1905 semi, double brick cavity walls with foam cavity wall insulation injected in there

the house had lots of issues including timber rot & damp. a few walls suffering from what looks a mixture of rising damp, penetrating damp & also hygroscopic salts around chimney breasts, all damp areas of the house are now back to brick.

Ive replaced all rotted timbers, treated remaining timbers, cleared out all air bricks, added extra air bricks & cleaned out the subfloor which im hoping will solve any future rot issues

Now the damp, ive cleaned out cavitys where possible, and also looking into replacing the exterior cracked render which i think could be a big cause of issues, but im aware that even once fixing damp cause, walls will hold moisture for a long time, so i need to decide how to tackle the plastering

My plan was: all damp areas that are back to brick, render with s&c with a waterproofer & salt inhibitor

Then dot and dab the lot

i then found out about cold spots etc and the danger of getting wet marks all over my new boarding,

so i then considered changing out the standard plasterboard for a foil backed board, until i read that they cannot be fixed using Dot & Dab,

which has now led me to maybe using insulated polystyrene backed blasterboard, which im hoping would act as a waterproof barrier as well as improve insulation???

What are people thoughts on this? Would this method hold back any residual damp and avoid getting damp dab marks all over the finish?

The boards i had in mind - 22mm

http://www.buildingmaterials.co.uk/gyproc-thermaline-basic-insulated-plasterboard.html

Thanks for reading

 

[jmd1994]

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[Nige F]

brick cavity walls with foam cavity wall insulation injected in there

the house had lots of issues including timber rot & damp. a few walls suffering from what looks a mixture of rising damp, penetrating damp & also hygroscopic salts around chimney breasts, all damp areas of the house are now back to brick.

I
Now the damp, ive cleaned out cavitys where possible, and also looking into replacing the exterior cracked render which i think could be a big cause of issues, but im aware that even once fixing damp cause, walls will hold moisture for a long time, so i need to decide how to tackle the plastering

Hello and welcome I'm not a plasterer but - The exterior render, is a large proportion of the walls cracked/needing removal+repair ? The reason I ask is because of the foam cavity fill - not a good thing to have,arguably the latest fibre is better but some say cavities should not be filled at all. It is possible to have the fill removed, and may be worth looking at because bricks taken out could be rendered over "en masse". Inside I would suggest sand+cement or sand/lime render set with plaster. I don't think plasterboard lining - even on battens rather than dot+dab would be as good a solution. Just some ideas for you to investigate, and probably some more experienced guys will reply too

 

[jmd1994]

Hello and welcome I'm not a plasterer but - The exterior render, is a large proportion of the walls cracked/needing removal+repair ? The reason I ask is because of the foam cavity fill - not a good thing to have,arguably the latest fibre is better but some say cavities should not be filled at all. It is possible to have the fill removed, and may be worth looking at because bricks taken out could be rendered over "en masse". Inside I would suggest sand+cement or sand/lime render set with plaster. I don't think plasterboard lining - even on battens rather than dot+dab would be as good a solution. Just some ideas for you to investigate, and probably some more experienced guys will reply too

Hi and thanks for your reply!

So the insulation IS the old foam type!! I got that checked out during the survey on the property, ive heard there can be a few problems caused by it i.e wall ties degrading also, i have a guarentee so maybd need to take it further

So the exterior render, the front & back of the property is in a serviceable condition, barely any cracks, the gable though will be coming off for sure, its pretty badly cracked.

Thanks for the thoughts on patching and re-skimming, its not the first time its been advised, there seems to be a split on opinions, i had just been more keen on the boarding to get a perfect finish, hide a few sins and also create a kind of vapour barrier between the drying walls and my finish, the more input the better though, as i am up for adjusting my plans