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. 

[Spinny]

@Nickfromwales and everyone...

 

Have finally been messing with this. Tried just cutting half the width of the celcon block down under the edge of the cavity closer only, to sit the cavity closer down more level. But when I put board in on top there is still movement in the cavity closer on the door side above the cavity, and with nothing to fix to I can't see a way to make it rigid. Board could be screwed or glued to the celcon block but the 'cantilever' above the door side still will not be rigid. So I am going to have to cut the cavity closer out, as per your solution Nick, and start messing about to cement fill and insulate the cavity.

 

Some questions...

 

Why did you say don't let the SLC come into contact with the masonry in the post above ?

How do I stop the cement running down the cavity ? Keep it a stiff mix, and put something underneath like cardboard to act as form work ?

How do I fix the insulation to the outer block so it cannot move or flex downwards ? (I have some rigid 30mm XPS) Screw it into the block ?

What is the best thing for fixing the inner side of the backer board firmly down onto the celcon block without the celcon block breaking up ?

 

 

 

 

Edited September 5 by Spinny

[Spinny]

Current state of play now in the photo.

 

Couldn't get a stable piece of board with the cavity closer underneath, so have bitten the bullet and cut it out and removed it.

Have cut the Celcon block down so it is currently about 12mm below top of floor cover boards.

Cavity has graphite EPS below DPC as spec. I can remove one piece which was rocking on a wall tie. The other piece is joined into a larger piece and not removeable - I have cut it down a little.

 

What next ?

 

All I need really is something in the cavity to remove the cantilever over the cavity.

If I cut down the EPS to leave a gap above it of say 2 inches and fill with a quick setting concrete mix, and an upstand of 30mm XPS on the door side - will that be good enough to reduce the cantilever to just 30mm ? Is 2 inches enough ?

 

Yes I know, but is 2 inches of concrete enough ?

 

 

Edited September 5 by Spinny

[Spinny]

Any advice appreciated here, 'cause I am stuck scratching my head with plasterers coming on monday.

[Spinny]

Still dunno what to do here...

 

Contemplating whether to try to screw angle brackets to the outer concrete block leaf to support some closure ? Would Toupret exterior filler stick to the inner celcon block ? (though I am nervous of exerting sidways forces onto blocks the builder struggled to mortar well.

[crispy_wafer]

did you try or think about what @Nickfromwales suggested eps at the bottom of the cavity, xps board against the outer leaf to insulate against the cold bridges then fill with concrete.

Edited Thursday at 14:04 by crispy_wafer

[Spinny]

51 minutes ago, crispy_wafer said:

did you try or think about what @Nickfromwales suggested eps at the bottom of the cavity, xps board against the outer leaf to insulate against the cold bridges then fill with concrete.

Yes I was thinking of that. However having opened things up I have the following concerns:

 

A. The existing EPS on one side already reaches down to the bottom of the cavity but still has some movement in it and so doesn't seem rigid enough to offer any support to any concrete above.

B. So the only thing that would seem to be supporting any concrete would be it's sideways bond to the inner celcon blocks and two things concern me - 1. Can I get a strong bond to the celcon blocks or might it break away over time and - 2. vertical weight onto the concrete would create a turning force onto the selcon block and might pull on its mortar joint loosening it. Our builder had issues fixing celcon blocks elsewhere in the build and it makes me nervous of putting them under anything other than vertical forces.

C. The outer leaf concrete block was damp where is goes below ground (to be expected I suppose with the rain we have had) and there was some moisture on the bottom of the EPS in the cavity there, so uncertain whether a small moisture gap under the EPS was better than pushing it hard down onto the bottom of the cavity.

 

Photo shows a test fixing of an angle bracket into a surplus faced concrete block - which make up the outer leaf. Thought being could I put one every 150mm or so across the reveal to support a board over the cavity. (putting some DPM behind each one and XPS around). Not very easy to fix with a celcon block just 100mm away of course

 

Have also thought about say angle brackets with one leg long enough (say 150mm) to span the cavity and so be also fixed vertically into the top of the celcon block. Yes a thermal bridge between outer and inner leaf, but with insulation board on top and the celcon blocks maybe not too much of a compromise to matter.

 

And that is where I am, caught in the headlights a bit like this guy...https://youtu.be/GezQvcbPaYY?feature=shared

 

[Spinny]

@Nickfromwales Any more thoughts to offer on this one ?

[Nickfromwales]

8 hours ago, Spinny said:

@Nickfromwales Any more thoughts to offer on this one ?

Yup.

 

You are overthinking, so stop it! Lol. 😜. 
 

If you’d like to move on with your life, please do the following.

 

Get some Marmox or ‘other’ tile backer board from a local tile supply outlet (Topps carry these at 6 and 10mm). Get a couple of sheets and cut the first one to drop down into the void to fit against the outer wall completely; for the first piece going against the door you need to leave this as high and wide as possible to act as a shutter to stop the SLC / concrete getting to the masonry. Get some Illbruck FM330 foam to use to bond this to the masonry, and use it to seal the edges, eg so no external masonry can be seen, just board and foam. Leave to cure, then cut back any foam snots. You’ll need something forced into the void to keep the board in place whilst the foam cures. Buy the proper gun grade foam and a decent gun, not the cans with the single use bendy straw!!! 

 

Then do the same again against the internal block, leaving it high again. Leave to cure, same detail. 

 

Cut a few more pieces of the board to drop in between these taller boards, full width, say 35mm shy of the level you want for the flooring to fly over. Keep cutting these and dropping them in until the gap is pretty much full of backer boards, like a sandwich. For today’s exercise the sandwich will be a BLT. 

 

Once happy the void is as full of boards as it can get, withdraw these shorter boards and set to one side.

 

Soak the area with water, immediately prior to the next steps. Sopping wet is fine, bone dry is bad.
 

Then you drizzle about 3” of foam into the bottom of the void, so there’s an entire bed of it at the bottom, left / right / centre and front / back. The slower the foam comes out of the gun the better the bed of foam will be. Then go back and forth from bottom to top to cover each piece of white EPS in the cavity as best you can. 

 

Then immediately drop the cut boards down into the wet foam, one at a time, applying foam to the back of each, and then setting it upright against the last; as the gap gets tighter you’ll be able to apply less and less foam, don’t worry about it, just get as much in as you can.
 

Then fill the remaining gaps at the top and sides with foam and leave to cure for about 2hrs; you can force the foam gun nozzle down into the gaps to get it most of the way down, but don’t push on the canister! Do this obvs whilst the foam is all still wet. It gets messy so keep one hand on the gun handle and a glove on the other to move the boards about. Set the foam to come out slowly so you can squeeze the trigger without having it come out at a crazy pace; this is easier than trying to manage the job and be the throttle for the foam at the same time. Have some gun cleaner to hand for any cleanups.

 

Prob a good idea to have some weight of some sort to keep the boards held down whilst the foam cures. Get a rubble sack or bin liner and wrap the underside of the door and the threshold, as the foam (when left unattended) has a life of its own and can spew out and get on to the things you don’t want it to. Keep an eye on it for the hour or two that the foam is still curing.
 

Once set you can cut / neaten the foam; you’ll then have a rock solid basket ready to take concrete backfill.

 

Use 10mm aggregate, or just use Mapei builders screed (which has fibres in it) and back fill as required. Once cured, cut the taller boards back so suit. 

 

Using the “Marmox BLT” method will leave you with a series of XPS boards which are sitting down on the substructure, and that’ll be good enough to go barn dancing on. 

Yee-ha! 🤠. 
 

The end.