Gap behind botched door lining - how to hang a door?

[chris1982]

Hi all,

I was hoping to hang an internal door where there hasn't been one before, but there is something in place that looks like a door lining, which a previous owner had installed when the house was extended and I believe a UPVC external door was removed.

I drilled an exploratory pilot hole where an hinge will need to go. The lining seems to be MDF, but the problem I discovered is that behind it there is about 5cm of nothing. I had hoped for something that could take the weight of the door, but there is a massive gap to the brick wall and apparently no timber in place. So I don't know what to do.

Are there specialist long fixings? Something like long but thin masonry screws, or frame fixings that are longer than the ones I seem to find?
Or will I need to take down the lining (and the architraves) and put some timber behind?

Thanks in advance.

 

[foxhole]

You could drill holes in 4-5 places down the lining and pump in some adhesive foam which will stabilize the lining, if you have enough width fix a new lining inside the existing and you will have plenty to fix too.

 

[chris1982]

Thanks for the suggestion. I didn't think of expanding foam. Do you think that is strong enough?
If I took the existing lining down I would want to make the opening actually a bit smaller which would mean taking less of the door. What is the best way of fixing the lining though?

 

[JohnD]

it's not clear what this MDF lining is fixed to. No studs in the wall? so is it just glued to plasterboard?

Expanding foam (preferably pink fire grade) will actually hold a door lining in a brick or block wall, or to studs, although in UK I think screws are always used first.

But it won't stick to air.

I recall that the installation instructions for fire foam say it should be used to fill small gaps, large gaps should be made up with timber or other materials. I can't remember the size though. If there is a stud in the wall you could fix some measured blocks to screw the lining to.

If filling large cavities, apply foam in segments or layers. If you apply enough to fill the cavity it has nowhere to go when it expands and can buckle or break some materials.

 

[chris1982]

Thanks. I don't know what is behind the lining that is currently there, but it is where someone knocked through a previously external cavity wall. The door needs to go on the side of the outer leaf.

 

[foxhole]

Does not need fire foam current fixing foam will easily secure and fill 50mm in one go.Have used it in exactly same scenario with my daughters extension.

 

[chris1982]

Right, that is foam to hold the lining but not the weight of the (heavy) door?

 

[JohnD]

I've never tried it myself, but in another European country, the builders installed a houseful of doorsets by propping them into position and injecting foam. Spacers and wedges but no screws. That's why I'd go for fire foam, rather than having the doors fall out in a fire.

I use wedges, screws; then foam afterwards to fill the gap and prevent any rattling or loosening if you have teenage girls in the house, slamming the doors. Also to cut noise, draughts and smoke penetration.

 

[Deleted member 174758]

I've never tried it myself, but in another European country, the builders installed a houseful of doorsets by propping them into position and injecting foam. Spacers and wedges but no screws. That's why I'd go for fire foam, rather than having the doors fall out in a fire.

I've done one hotel refurnb here where we jigged up the door frames on a steel jig, offered it in, levelled it and then foamed it in. 30 minutes later we came back and screwed the casing in to meet the requirements. Worked well and was super quick to do.

 

[Gerrydelasel]

The lining seems to be MDF, but the problem I discovered is that behind it there is about 5cm of nothing. I had hoped for something that could take the weight of the door, but there is a massive gap to the brick wall and apparently no timber in place.

Are you saying you don't think the screws will have enough wood to fix into? In that case just glue some scrap pieces of wood behind the MDF casing, where the hinges will be positioned. Fill the remaining air gap with foam.

 

[foxhole]

Don't think there is access behind, when OP drilled test hole found a gap but this is probably just hitting space in brickwork or the bricks 'frog'.

 

[chris1982]

Thanks guys. There are indeed no "blocks for ninge screws" (at least not where I looked), but just two inches of air, so I will need to take the entire thing down...

 

[foxhole]

Thanks guys. There are indeed no "blocks for ninge screws" (at least not where I looked), but just two inches of air, so I will need to take the entire thing down...

Why?

 

[chris1982]

Why?

So I now guess I am missing something , and get my hopes up that you will tell me an easier way...

The lining seems to be supported by some timber only in the middle. The hinges need to go by the side (such that they are flush with the wall if that makes sense). So just where the hinges need to get screwed in, there is only a few mms of MDF, then "thin air" of 5cm depth, followed by the edge of bricks (from the cavity wall that used to be the outside wall) or perhaps even just plaster.

How can I secure the hinges in a way that they can take the weight of the door? It's quite a heavy door (with glass panels).

Putting the screws into foam? Or how would I get a block of wood behind the lining without taking it down?

I suppose I could could cut out a piece just as large as the hinge, but then I am not sure how I can secure that on the wall. If I used screws to attach such a small block to the wall, I don't know whether they will be enough free "timber" to put in screws that hold the hinge.

Please tell me what I am missing!

 

[Gerrydelasel]

Or how would I get a block of wood behind the lining without taking it down?

Remove the one piece of architrave