badly bricked up patio door opening - How do I fix this ?

[Ron Gamma]

Hi,

Moved into the house in 2005 but this window change was ordered by previous owner in 2000. They had a patio door removed and bricked up the lower 800mm across the 1850mm wide opening topped with UPVC window above that.
In 2007 I found that there was a 40mm gap above the header with no fixings or foam, just plastic trim over the top. I filled the gap with expanding foam to glue it to the concrete lintel and kill the sound leaking through. I chiselled out the mouldy bottom corners and replastered the reveal thinking it was a condensation issue from the empty void I had just filled.

Skip forward to this year's project to make a home office. I am reducing the width of the window so took the inner cill off last night to cut it down. I found the cill was mastic'd to the thermalite inner wall and in doing so it dislodged the entire top course of blocks leaving the plasterboard finish intact. I also then discovered why the draughts and mould were appearing. No cavity insulation and no sealing at the ends of the outer cill to window frame. In addition there are no brick ties between the courses or where they join the original window reveal - they appear to have mortared onto the painted surface only.

The picture isn't great but here are the questions:
1.For an 1850mm wide x 800mm deep section of cavity wall that only supports a UPVC window does this need to have brick ties?
2. If it does, what can I do to retrofit? (I don't mind taking down the inner course but want to avoid damaging the outer skin)
3. What would be the best insulation to fit to this cavity
Would expanding foam be suitable for the cavity and act as a way of securing the two skins or would this generate a new damp problem?
4. Shouldn't the top course of thermalite blocks actually close the cavity rather than have the inner cill acting as the closer?
5. As the inner skin does not appear to be tied or keyed into the original wall should I rip the entire inner skin down and rebuild it as I will be wanting to hang an 800 x 600 radiator from it?

As usual any help will be much appreciated.

Thanks.

 

[Blagard]

Messy and really a bit of a bodge,

1. It is not a serious structural problem so I would just leave it
2. N/A
3. Perhaps the same as used elsewhere if you can see it. I would not use expanding foam as that could exert a pressure to force the brick/block leafs apart. Hopefully you can simply Slot some cavity insulation in from above to suit the cavity size.
4. Not always by block, you could use an insulated cavity closer like http://www.wickes.co.uk/invt/194006 but check the size first.
5. Building in some ties to the jambs might be worthwhile, especially near the top. There really ought to be ties in there already so if the outer brick has been bonded in assume there are ties on the inside to do similar (unless it is loose!).

 

[Ron Gamma]

Hi Blagard, thanks for responding.

I took the loose top course off last night to clean back ready to refit and found the next course down was wobbly so I lifted that out as well...and the next course and right down to the floor level. The whole lot had seperated but couldn't be seen behind the pb. The mortar was like concrete and had stuck to some blocks but not others. There was only 1 nail into the lefthand jamb to secure it.

They had dry lined the wall and stuck the pb on with flexible frame sealant. It was set but pliable. To stop it sliding down the wall they had used 4 woodscrews into the blocks at random points.

I have bought new blocks to remake the inner wall and will tie them in at the jambs with starter plates. I will fill the cavity with 50mm T&G polystyrene boards.

 

[Blagard]

Starter plates are fine but you could use frame cramps if you wanted to.

Likewise with the blocks out of the way you can use similar to tie the bricks to the blocks. The same way brickwork is sometimes tied back to a concrete wall.

http://www.ancon.co.uk/products/wall-ties-and-restraint-fixings/other-restraint-fixings/frame-cramps

Use SDB or similar in the cavity and again at the jambs if you want to save buying two types!