Internal wall cavity below DPC

[stavros.london]

Hi all,

I was struggling to find an appropriate title for this post, so hopefully the description here will clarify:

I've just built an single storey rear extension, which turned a 1 meter brick-cavity-block wall from external to internal as per the below diagram

I want to keep that internal wall as separation for some kitchen units, but I wanted to remove the internal blocks and leave just the brickwork in order to gain another 250mm or so of space (block + cavity). My question is around the cavity that will remain at the floor level and below: should I fill it in in order to provide a more solid base for the sub-floor / insulation boards? And if so, what should I fill it in with? Any other options / considerations?

Thanks in advance

 

[tomfe]

How will you be supporting the the internal wall above what you are taking out?

Treat the cavity and internal block as you would a floor. DPM insulation screed.

 

[stavros.london]

Perhaps I wasn't very clear. The wall that became internal after the extension, consists of brick-cavity-block. There is no reason to keep the cavity and inner block since this is now a totally internal wall, so I want to remove the blocks. The cavity however continues below current floor level so I'm wondering how I can e.g. add floor insulation boards in that area since there will be the hole of what used to be the wall cavity. If I can fill in that cavity below floor level somehow then I have something more solid to support the floor insulation boards.

I hope this makes sense

 

[vinn]

Photos make sense.