dot and dab external wall the best solution?

[DartArms]

Hi,

So I have a landing wall that needs to be skimmed and a window reveal built up as an old wooden sash has been replaced by a upvc window and it's much smaller and thinner than the old window.

Now the situation is a bit complex as we have a solid, non cavity, wall where the window is, this runs into a timber internal stud wall part way along. And at the same point as the join there are 3 stairs. Obviously there are cracks all over the wall where the solid wall runs into the stud wall.

We can't afford to lose any space as this is a hallway/landing. This means any insulated plasterboard is out of the question (I assume) as we only have approx 25mm to play with once the existing render is hacked off the wall.

Someone has suggested using dot and dab with plasterboard on the brick wall and running this straight onto the stud wall and just ensuring that the board sits in the middle of the joint to reduce the risk of cracking.

I'm concerned that we might have issues with cold spots and damp if we dot and dab onto the external wall. There is currently no issues with damp on this wall currently and it's on the 1st floor so no problem with rising damp.

Is there a way to dot and dab and use some products that would avoid any cold spots/damp issues? Or would some other kind of solution be possible that could fit within the 25mm depth we have available?

I can provide a diagram if it's not clear what I'm working with from my description.

Thanks

 

[RandomGrinch]

I'm a DIY'er, so not an expert, feel free to ignore!
I have found this stuff really useful and easy to use (although the boards will need some support while curing):
https://www.toolstation.com/soudal-plasterboard-adhesive-foam/p99304
It holds the boards just as firmly as dot and dab, but has a little flexibility to help avoid cracks as well as taking very little depth to fix. It also helps avoid damp spots and cold bridging (but that also means it hides any problems that may be occuring out of sight!).
I've also seen this flexible filler:
https://www.toolstation.com/toupret-fibacryl-flexible-filler/p40082
Being recommended for the sort of cracks you get between brick and stud walls.

 

[Bouy]

1. Not advisable to dot and dab on external walls unless - "This method is suitable for use on brick, block or concrete cavity or rendered solid walls, which are dry, stable and free from moisture penetration." - Info as per Kingspan K118 brochure sitework section and "Drywall adhesive dab bonding must always be used in conjunction with a bonding agent applied to the foil facer, as per the following sitework instructions."
2. Basically dot dabbing plasterboard on a solid brick wall could lead to condensation problems in the cavity area at the back of the plasterboard, even more so if there isn't a VP to prevent water vapour on the room side permeating through.

 

[DartArms]

Just been doing a bit of searching around, has anyone used one of these damp proof membrane systems that can be dot and dabbed over? I assume if they can be used in basements with damp walls then it would stop any issues on a dry wall with no problems? Would this also prevent any cold spots and cold bridging?

Something like this https://allianceremedialsupplies.co.uk/product/damp-proofing-mesh-membrane-kit/