How should reveals be done on 1930s house

jesteh · 7 Aug 2010

Another question about reveals.

We have 1930s house with 50mm cavity. The windows openings are closed with brick on the side of the window with gaps on top and bottom. The bottom gap has just a wooden window board over it, top gap has a wooden lintel above.

Plasterer has closed the reveals with plasterboard. He's first put some cavity closers on the top (which I insisted on - he was going to use roll of rockwool). He's then used 12.5mm and plasterboard to level off the reveal on top around the lintel with some battens in between to hold it in place. Is that good enough? I am specifically thinking about things like cold bridging as we are having cavity walls filled with beads. Nothing was done with cavity opening on the bottom (although I guess that'll be filled with beads to the board)

marshman · 7 Aug 2010

You'll have to post a picture on this one,
unless rc can knows what your describing.

Micilin · 7 Aug 2010

If you have a cavity closer in place, you should have very little , or ideally none of the outside skin showing. If your dabs fixing the plasterboard are put onto the inner skin and c/closer without touching the outer skin, you will have no problem with bridging.

If any outer skin is showing, I would prefer a wide DPC tucked into the cavity, (this can be held in place by the c/closer if you like) and this is then wrapped in around towards the window , to cover the outer skin, and lapping onto the window frame. The p/board can then be stuck, and the excess DPC cut off afterwards. The dabs on hold the inner skin will be enough to secure the p/boards.

I would make sure that any gaps around your frames are sealed up first - this would have been done with a dpc in the past but mastic nowadays.

jesteh · 7 Aug 2010

I've attached a picture of one of the windows.

The windows are pushed quite a bit out and the out skin is exposed. There is only cavity closer on the top - on the bottom its only a plank of wood.

marshman · 7 Aug 2010

Its fine, he's brought the wood lintel out flush with the brickwork ready for a float coat and he's lowered the head to give you an even
window frame, looks like you're got a good plasterer who knows what he's doing.

Micilin · 7 Aug 2010

marshman said:
Its fine, he's brought the wood lintel out flush with the brickwork ready for a float coat and he's lowered the head to give you an even
window frame, looks like you're got a good plasterer who knows what he's doing.

Yes, I agree - although I prefer a 'Scottish and Newcastle' red crate myself.

jesteh · 7 Aug 2010

ok, what about all the business with mastic? do i need to stick some of that stuff in as well?

Micilin · 7 Aug 2010

jesteh said:
ok, what about all the business with mastic? do i need to stick some of that stuff in as well?

The idea is that

1 your plaster inside does not make contact with the outside skin of brick or external finishing ( if you don't have solid walls)

2 there will be no ingress of water through the gap between frame and wall.

If you have a cavity that won't take a c/closer, put some dpc in the cavity as mentioned above, against the outer skin and fill the inner side with mortar. Before you do this make sure the window frame is properly sealed all around.

If I was fitting windows in this kind of scenario , I'd have this DPC in first . Put in so that it laps out onto the outside reveal, past where the window is to be fixed. Then when the window is fitted up against the DPC, the internal reveal is weather proofed behind the DPC.

I can't really see a cavity in your pic?

jesteh · 7 Aug 2010

Here's another picture, this time without reveal. Its not immediately obvious but window edge is flush with outer skin edge

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How should reveals be done on 1930s house

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