Cavity closure issue

[pilsbury]

Spreading plaster all next week, then self levelling compound going down to level things up before tiling. Levels aren’t too bad but need a little helping hand to merge my old floor and new.

I see a problem. I fitted cavity closers all round the doors. Sides and top are no problem, but the floor closer could be an issue. The doors are pretty much flush with the inside of the outer skin. So all that’s holding the closers up are the thin plastic flanges on each side. If I stood directly on them I’d bust them and my foot would be in the cavity. If I self level over them, then tile on top, I worry if someone stands close to the door the tiles might crack. Basically that 4” edge has very little support.

What’s the fix apart from blocking the cavity up and creating a cold bridge?

 

[noseall]

What’s the fix apart from blocking the cavity up and creating a cold bridge?

You would typically remove the uppermost part of the masonry spanning across the doorway on the inner leaf, lay polythene in the trough and screed right up to the door threshold.

You can fit some 25mm insulation against the external masonry but this could create problems with carpet grippers etc.

Those doors are one big (cold) thermal element in any case.

 

[pilsbury]

I suppose there could be some damp transfer across the cavity hence the polythene.

 

[^woody^]

Spreading plaster all next week, then self levelling compound going down to level things up before tiling

That's a novel use of self-levelling compound. But may I suggest a product called "finish plaster".

 

[pilsbury]

Luckily for me all my skill levels and experience across all disciplines are equal. May well need to use self levelling compound on the walls after skimming.