Cavity closure problem (with picture)

[ex_directory]

Hi, have had an extension with bi-fold doors. The main floor was screeded first but as the doors went in afterwards and sit lower than the screed they were not able to screed up to the doors at the time.

Now I have an open cavity, they have unsuccessfully tried twice to fill the cavity and screed over but the screed has cracked and moved. Next week they come back for hopefully the final time.

The last time they used thin slate tiles but I don't think they made an effort to ensure the tiles sat on both skins properly.

I am thinking of buying some creasing tiles to bridge the gap instead of slate before they put the screed on.

Diagram shows the problem...

Any comments much appreciated!

 

[masona]

Cavity closer?

 

[ex_directory]

I think given the cracking already taken place in the screed (remembering this is a heavy use walkway), the bridge has to be solid.

Hence slate/creasing tiles. I looked at the rigid pvc cavity closure but even that had some give.

 

[r896neo]

The best way is to line the trough with dpm and fill it with concrete

 

[simonjay]

The best way is to line the trough with dpm and fill it with concrete

In order to avoid cold bridging at the doorway,
what you should really do is remove a course of bricks from the inner leaf, fill the cavity trough with DPM / concrete up to the level of the beam and block, then run insulation right across the lot up to the door and screed across the top (with an upstand of insulation at the door if possible).
I'm not saying that's what I did though ...
Simon.

 

[ex_directory]

I think the area is too large for dpm + concrete.

I may have to go for slate again OR I could buy a rigid pvc cavity closure and add slate on top.

Also, when I removed the old screed, I noticed they had trapped some celotex between the skins just below the slate. Should I do this again?

 

[r896neo]

Not sure what you mean by too large for concrete? do you mean the cavity is very deep?

 

[seasickstevie]

... Should I do this again?

Think Simon gave you the solution

 

[ex_directory]

Yes, cavity is deep and 7m long.

Simon may have provided the answer, but I guess I was suggesting slate instead of concrete - so is there still a need for insulation and am I creating a cold bridge with my solution?

 

[^woody^]

Fill the threshold with expanding foam, then slate or mesh and then screed over it

 

[ex_directory]

Fill the threshold with expanding foam, then slate or mesh and then screed over it

Actually I was thinking of cutting down a sheet of celotex and jamming this in the gap just below the slate - will that do it??