Hoping someone can point me in the right direction with this one! I’ve done a lot of searching about but can’t quite find what I’m looking for.
I have a ground floor window opening which is 7ft high (goes right to the floor) and 8ft wide, I want to reduce the opening so that it’s just 4ft high by putting a 3ftx8ft infill panel in the bottom part of the opening and a new window above. The other half, for aesthetic reasons, wants this panel to be timber clad.
The construction of the existing house is uninsulated block cavity walls (early 70’s), although above the window in question forming the wall of the first floor to the front there is a very simple 4” timber frame with concrete boarding to the exterior and PB to the interior. So at the window opening in question, I have cavity walls to the bottom and at both sides – and then to the top there is a lintel over the outer block work which supports the timber framing above. The current window, then, is sitting on the outer leaf of block.
So the question is how, within regs, do you build and support that panel? If I look at the TRADA specs for this then it looks to me like the timber panel should be built on the internal leaf of brick with a cavity and then the timber cladding. But that won’t work, because the window needs to sit on the panel and then the top of it won’t line up with the existing structure above and there will be a big gap.
My first thought was just to put it all on the outer leaf, but I can’t see how to get enough depth to get a timber frame with a low enough U-value to satisfy BC and still have room for the timber cladding, all within 100mm. My current idea is to put cavity closers in and then install a thicker panel (184 maybe) which bridges over the cavity and sits on both the inner and outer leaf of brick with DPC in-between. I can then position this to get the window in the right place so it lines up with the structure overhead and get my timber cladding sitting in the opening too (rather than sticking out of it!). But is that really the best solution?
I should add I’m in Scotland, which might make a small difference regs wise – but even getting an idea about how this would be done anywhere in the country would be a big help!
Many thanks!
I have a ground floor window opening which is 7ft high (goes right to the floor) and 8ft wide, I want to reduce the opening so that it’s just 4ft high by putting a 3ftx8ft infill panel in the bottom part of the opening and a new window above. The other half, for aesthetic reasons, wants this panel to be timber clad.
The construction of the existing house is uninsulated block cavity walls (early 70’s), although above the window in question forming the wall of the first floor to the front there is a very simple 4” timber frame with concrete boarding to the exterior and PB to the interior. So at the window opening in question, I have cavity walls to the bottom and at both sides – and then to the top there is a lintel over the outer block work which supports the timber framing above. The current window, then, is sitting on the outer leaf of block.
So the question is how, within regs, do you build and support that panel? If I look at the TRADA specs for this then it looks to me like the timber panel should be built on the internal leaf of brick with a cavity and then the timber cladding. But that won’t work, because the window needs to sit on the panel and then the top of it won’t line up with the existing structure above and there will be a big gap.
My first thought was just to put it all on the outer leaf, but I can’t see how to get enough depth to get a timber frame with a low enough U-value to satisfy BC and still have room for the timber cladding, all within 100mm. My current idea is to put cavity closers in and then install a thicker panel (184 maybe) which bridges over the cavity and sits on both the inner and outer leaf of brick with DPC in-between. I can then position this to get the window in the right place so it lines up with the structure overhead and get my timber cladding sitting in the opening too (rather than sticking out of it!). But is that really the best solution?
I should add I’m in Scotland, which might make a small difference regs wise – but even getting an idea about how this would be done anywhere in the country would be a big help!
Many thanks!
