Cavity Wall Gap (Internal to house)

[RichDarbey]

I realise that this topic has been discussed a number of times in this forum however based on searches I have been unable to find a similar example.

I have an opening between two internal rooms however one room was an extension therefore the opening between them used to be an external wall. I have therefore got a cavity gap that requires filling.

I have read a number of posts which suggest that a DPM trough can be created to bridge the gap.

In my example I have a couple of differences to previous posts:
1. The opening is an internal room to extension internal room
2. The existing DPC in floorboarded room is two layers of slate
3. I have central heating pipes that bridge the gap.

I have attached pictures and was after advice how to address the issue so I can have a screed floor that levels at same height of floor boards.

My current idea is to place a sheet of DPM laid flat on the concrete sub floor of one room (under pipes), continues into a trough and then lapped to the floorboards. Screed the poured so continuous level

Many Thanks

Untitled

• RichDarbey
• 20 Sep 2011
• 1

Untitled

• RichDarbey
• 20 Sep 2011
• 1

 

[noseall]

You ned to fill in and level-up the voids that exist i.e. the brick cavity, where the brick is missing, then lay your dpm on top of this smoother surface, then lay your screed.

It may also be an idea to screw another joist to the ends of those floor boards just to act as a shutter to prevent material falling into the void. slip some dpc under it where it comes into contact with the brick course below.

Is that an air vent pie i can see?

 

[RichDarbey]

Hi Noseall, Thanks for your reply.

I understand what you mean with regard to level-up the brick work but how will this be achieved where the pipes pass through as the gap only exists because the brick course has been lowered by one brick. If I bring the brick course up then I will have to drill joists for pipes..

You also then say lay dpm on top so I think you mean just bridge the cavity and the screed on top? I assume then the gap between does not need to be filled in a `trough`?

You are also right that you can spot an air vent so I was going to just extend that slightly but with a small pipe. WOuld that be ok?

SHould state that previously this whole area was just screeded - DPC was slate, screed bridged the two brick courses and the void filled to top with building rubbish (This void is still full on pic but intend to remove so cavity is empty)

 

[noseall]

So long as you can get a decent thickness of screed, have a smoothish surface for the dpm to go on and that you don't interfere with the air vent, then fill ya boots.

The cavity brick wall you see is irrelevant now and acts only to support the screed. You were right to remove the bricks in order to achieve a decent screed thickness.

 

[RichDarbey]

Just to clarify then that filling the cavity is ok and bridging the two walls does not matter now that this cavity is an internal wall. The only important factor is to ensure a DPM is placed over the whole area before screeding. If you could just confirm that my understanding is correct?

Thanks Rich

 

[noseall]

Just to clarify then that filling the cavity is ok and bridging the two walls does not matter now that this cavity is an internal wall. The only important factor is to ensure a DPM is placed over the whole area before screeding. If you could just confirm that my understanding is correct?

Correct.