Hello, also consider which way your extension faces...e.g. north or south facing etc, if north facing, I think 2 big square windows ( perhaps SK08 or UK08 size as you have a wide house ) will let in more light. If you have 2 huge ones for south facing and also sliding doors, it could get very hot in the summer. I'm in the middle of my extension 3m x 5m , north facing garden, I have 3 velux MK08 which is 78cmx140cm, I've always liked the look of 3 windows instead of 2 but after they were installed I had second thoughts about whether I should have gone for 2 huge square ones instead as I also didn't take into account that we've have just had a dormer loft conversion completed, it takes a little longer for the light to come over to the back of the garden. Looking at your plan, you could have 3xPK08 94cmx140cm. The edge of the middle velux will be in line with where your sliding doors starts so that could look nice. Or if you have 2, you could have the edge of the second velux starting where the sliding door starts? I wouldn't go shorter than 140cm in length because when you are standing far inside, you want to see more window, if you go shorter, the windows will be 'hidden' behind the steel beams, make sure your builder install them so that the bottom of the velux is closer to the sliding doors rather than closer to the pitch roof. Do you want at least one window that opens with a remote control? Here are my windows, it might help you to visualise..MK08

Thanks. The seat is 50cms deep and was originally designed by an architect to be a window seat. It still has the same solid support for the first 40cms depth, I've just removed the original decorative panel and replaced it with a very thin radiator. The old wooden front panel and supports would probably still have fitted back in place but I disliked it and threw it out, and it wouldn't have been easy to perforate. I'd been trying to avoid a metal screen, as I can imagine it will clang a bit if someone's sitting on the seat and swinging their legs. But it's a good idea apart from that. My current thought is to have a fixed panel in the middle and some hinged doors at each end of the radiator (for access) ,with the MDF attached to the front edge of the seat rather than fitted underneath. I'll go and take a look at those metal sheets thought :)

Though a veneer may not fluctuate in size like real oak it will wear out far quicker than a window seat made of solid oak, a very long lasting material. I think the judgement you have to make is whether the surfaces of your window seat need to be that hard wearing, the jointing and edges will also have to be well detailed to achieve something that looks as good as solid oak.

Do you mean an 'oriel' window? I don't know about pricing, but you can probably contact a couple of suppliers to give you estimates? A quick google and amongst loads of others these came up too. The IQ glass one gives some useful info on sizes I think: https://www.finepoint.glass/product/oriel-windows-london/ https://medium.com/iq-glass-uk/what-to-consider-when-specifying-an-oriel-window-cb39beedce04