Door Reveal Problem Help

[Spinny]

Need to solve flooring problem in a door reveal - see sketch & photos. Any help or thoughts much appreciated.

 

When the underfloor heating was laid the top board (green markings) was cut short at the inner leaf of blockwork at the door reveal - because the inner leaf of blockwork (celcon blocks) was too high to enable the top board to sail over into the reveal across the cavity and up to the window frame. So I now have a nasty gap in the flooring to resolve somehow. Floor person has already said it cannot just be filled with levelling compound. Top board is 12mm deep ply and the bottom of the ply is about 6mm below the top of the celcon block.

 

The wall cavity has some EPS insulation in it with a cavity closer over which has 20mm insulation attached. Cavity closer is now fixed under the door threshold on that side and where it crosses onto the celcon block then creates a high point.

 

To experiment I cut some 6mm eps tile backer board to sit in the gap as per one photo. When pushed down this lines up with top of the floor ply but the cavity closer makes it rock at that high point so not stable.

 

Options:

1. Cut the cavity closer out at the edge of the door and remove. Cut down the height of the celcon blocks across the reveal by 6mm or so using a multitool. Take up the flooring top board and replace with longer 12mm ply top board to run into the reveal and up to the door itself. (No real fixing at door edge as the door is positioned at the inside edge of the outer leaf - so edge is over the cavity)

 

2. Cut about 20mm of the celcon block underneath the inside edge of the cavity closer with a mutltool to lower it by 4mm so the cavity closer sits lower with no high point. Then fix a 6mm board into the reveal to fill the gap between existing floor and the door. One photo shows an EPS tile backer board cut to fit - perhaps ? this option would be better with 6mm cement board which would be stronger ?

 

3. Cut and remove the cavity closer but then somehow create fixings into the outer leaf below the door across the cavity to support the board in the reveal ?

 

As a doorway the floor is likely to be stepped on when coming in so needs to be stable - Floor finish will be LVT over latex onto the ply.

 

Eek.

 

Edited August 6 by Spinny

[BotusBuild]

What is the floorers reasoning for not using a leveller? Looking at the drawings, I would go that way; pre-seal the gaps around the sides of the area to be levelled to stop the leveller running away (a mistake I made) with tape or your favoured sealant (allowing it to set off), then apply leveller. Apply flooring.

 

There'll be an expert along soon 😉 

[Nickfromwales]

If it's going to take foot traffic, and then LVT, you ideally need to multi-tool the celcon blocks down by -22mm, install a 12mm XPS backer board (defo do not use cement board as it'll cold bridge like crazy), and then pour 10mm (min) of SLC to the required height to take the LVT over ply.

 

Multi-tooling the blocks will take an hour or so so that's easy enough to do.

 

Don't let the SLC contact any masonry.

[Spinny]

6 minutes ago, Nickfromwales said:

If it's going to take foot traffic, and then LVT, you ideally need to multi-tool the celcon blocks down by -22mm, install a 12mm XPS backer board (defo do not use cement board as it'll cold bridge like crazy), and then pour 10mm (min) of SLC to the required height to take the LVT over ply.

 

So you are saying I should cut off and remove the cavity closer ? (At the moment that is the only thing that actually bridges right across the cavity - one side trapped under the door threshold). 

With the cavity closer gone, how would I secure the XPS backer board on the door side of the cavity ?

[Spinny]

1 hour ago, BotusBuild said:

What is the floorers reasoning for not using a leveller?

That the area was not movement free and so 6-8mm of leveller onto the cavity closer/DPM would be liable to cracking up. Suggestion was to stop the flooring short of the reveal and insert and fix a metal/alu plate into the reveal as the finished floor. (This would look like the botch it is - so not really acceptable to me)

[Nickfromwales]

1 hour ago, Spinny said:

So you are saying I should cut off and remove the cavity closer ? (At the moment that is the only thing that actually bridges right across the cavity - one side trapped under the door threshold). 

With the cavity closer gone, how would I secure the XPS backer board on the door side of the cavity ?

The XPS backer board would be the closer then.

[Spinny]

I see 6mm fibre cement board is claimed to be equivalent to 24mm ply for strength and stability.

Could the thermal bridging be limited by stopping it short and inserting a strip of insulation between the edge and the door frame ?

[Spinny]

2 minutes ago, Nickfromwales said:

The XPS backer board would be the closer then.

Yes, but there would seem to be nothing to secure it underneath on the door side. One side would be supported by the cut down celcon block but the part over the cavity would be unsupported. At the moment the plastic cavity closer flexes (as they do), but it does rest onto the celcon block one side and then onto the outer concrete block leaf underneath the door threshold.

[Nickfromwales]

8 minutes ago, Spinny said:

Yes, but there would seem to be nothing to secure it underneath on the door side. One side would be supported by the cut down celcon block but the part over the cavity would be unsupported. At the moment the plastic cavity closer flexes (as they do), but it does rest onto the celcon block one side and then onto the outer concrete block leaf underneath the door threshold.

You'd push EPS down into the cavity, then you'd create an insulated upstand against the outer skin of masonry, with the XPS board, and then you'd fill the cavity with cement, level with the reduced celcon. Then you would use the XPS backer board to stop the cold rising connection, and then SLC.