Cheers folks. This is all useful stuff, because I don't have the fitting knowledge, and I'm relying on my common sense and some YouTube installation videos to try and satisfy myself about whether the job is being done properly.
To answer some of the questions:
Thermal breaks? I don't know what has been installed around the window. I can see expanding foam has been used between the bottom of the plastic cill and the wall on the window in the other room of the extension, but that looks to me just like a space filling exercise, rather than to create a thermal break.
As I mentioned above, the internal sills feel cool to me, which makes me suspect that heat is being lost under the window.
Cill top and end seals? Again, I don't know what's been done. I assume cill top refers to adding a sealant bead on the cill before screwing it to the window unit?
150 cill on a stone cill: It is a 150mm plastic cill on top of a stone cill. I bought the windows, but the spec and dimensions were checked by the builder. Is there any specific problem with this arrangement, or just the fact we have a redundant extra cill? I never thought about that until you pointed it out. It gets better and better...
To answer some of the questions:
Thermal breaks? I don't know what has been installed around the window. I can see expanding foam has been used between the bottom of the plastic cill and the wall on the window in the other room of the extension, but that looks to me just like a space filling exercise, rather than to create a thermal break.
As I mentioned above, the internal sills feel cool to me, which makes me suspect that heat is being lost under the window.
Cill top and end seals? Again, I don't know what's been done. I assume cill top refers to adding a sealant bead on the cill before screwing it to the window unit?
150 cill on a stone cill: It is a 150mm plastic cill on top of a stone cill. I bought the windows, but the spec and dimensions were checked by the builder. Is there any specific problem with this arrangement, or just the fact we have a redundant extra cill? I never thought about that until you pointed it out. It gets better and better...