How do you close a cavity below a door opening?

[mertotman]

If I have a door sat on the outside skin of a wall and the oversite and screed are contained within the inner skin, then how would I fill the gap created by the cavity please?

 

[noseall]

Just before you screed the floor you remove any inner skin material above the oversite concrete at any door openings. We deliberately lay a brick course on top of the last course of inner leaf blocks to be able to achieve this easily.

Once you remove this material you then lay dpm within the trough that is remaining then screed right up to the door frame sill.

If the builders have not done this then they don't know what they are doing.

Some builders deliberately set out the door openings when building the inner leaf, but this is only usually done when using the oversite concrete as the finishing floor surface, i.e. when power floating the oversite concrete to ffl.

 

[garyo]

The last time I did this on my conservatory I filled the 50mm cavity with concrete with two vertical DPC's either side, and one underneath. It was fiddly and doesn't look particularly atttractive.

Can you use a normal cavity closer, assuming that some kind of sturdy finished floor material is being used?

Nose- just to be clear, are you saying you'd remove the top row of inner leaf bricks just below DPC level, then extend the DPM so that it laps up the the inner side of the external leaf? As you say, I guess I may as well build the concrete floor that way to start with if the concrete will be the floor material.

Gary

 

[noseall]

Nose- just to be clear, are you saying you'd remove the top row of inner leaf bricks just below DPC level, then extend the DPM so that it laps up the the inner side of the external leaf?

Correct.

 

[Chukka63]

just a note for future works.if you know your door positions,return the foundation blockwork/brickwork at the correct point and then lay your hardcore/concrete etc as you would normally,then your DPM,slab are all nice and neat and no bricks to knock off later etc.

 

[garyo]

Hi Chukka,

Are you saying that the wall under the door position would become single skin for the couple of courses up to door level, and then run everthing including the insulation, slab etc, up to the inside of the outer skin?

I guess that's what Noseall was saying, but it didn't occur to me that I'd have insulation on top of the DPM, so would probably need more like three bricks worth / 1 block.

Gary

 

[noseall]

Are you saying that the wall under the door position would become single skin for the couple of courses up to door level, and then run everthing including the insulation, slab etc, up to the inside of the outer skin?

Correct. This is what i was stating here.....

Some builders deliberately set out the door openings when building the inner leaf, but this is only usually done when using the oversite concrete as the finishing floor surface, i.e. when power floating the oversite concrete to ffl.

 

[tim00]

Informative and interesting suggestions. Section views and a few pics would really help - says this computer illiterate.

 

[freddiemercurystwin]

@tom@vulcon I'll bite, vulcan dor cav reveals nothing on google ...

 

[Ivor Windybottom]

I saw a youtuber in his british newbuild, he pulled up the housebuilder's laminate flooring in the hallway and found the tops of the bricks and an open cavity directly under the laminate. This was a big mainstream housebuilder.

 

[Ivor Windybottom]

There shouldn't be an inner skin by the door, the inner wall should turn a corner and bump into the outer on either side of the door.

It should have PIR insulation underneath it and an upstand against the outer wall and reveals, plus the DPM.