Bi-fold Doors/windows

Feb 05, 2023 Last reply: 3 years ago 4 Replies

I have been watching a few building You Tube videos lately and have seen several extensions being built where the brickwork is dutifully cavity insulated only for a massive opening left on one wall for Bi-fold doors to be fitted and the trend seems to be to make these ever larger. Are these rooms going to be hard to keep warm? New housing tends to have small windows in comparison to 60/70’s housing (picture windows sold as giving a wonderful view but really a cost saving on brickwork). I thought the move to small windows was to make them more energy efficient?



From my own experience despite double glazing heat loss can be considerable where there is large windows. The previous owners of our bungalow added a conservatory onto a bedroom and combined the two into a single room with no doorway between them. When we first moved in it was quite noticeable how the conservatory room cooled a lot more rapid than the rest of the house. We had the double glazed roof removed and an insulated roof to replace it and this had a marked effect on heat retention but still this room tends to cool more rapidly and only remains warm because we can control the heat literally room by room.



My daughter has a new build that in most rooms has small windows except the kitchen/diner which is a DG french window 4 panels not the whole wall and she found it cool when working from home.



With the high energy prices are all these projects a nice little earner in the offing with builders recalled in the future to brick up some of these openings?



Richard


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I've long thought that if I were ever to move somewhere with such large windows/doors I'd try PIR insulation sandwiched between thin ply and framed by boards, with magnets sunk in them to mate with washers glued to the glass to put up and down (incrementally) with the seasons.

Yes.

Earlier building regs required IIRC that the glass area of a room's windows had to be at least 10% of the floor area, with the opening part at least 5% of the floor area. Big rooms meant big windows.

Whatever importance that requirement had was obviously insignificant compared with the sudden rise in fuel prices of the 70s.

That's wrong, it costs a lot more than brickwork even if its only single glazing.

When we had our extension we had to have a heat loss calculation to get planning permission. We have bifolds with 5 doors which more or less go across the whole of the back of the house. The extension is very well insulated and isn't a problem to heat. As it is South facing the thermal gain is quite significant on sunny days.

I seem to recall a conservatory without a door into the main building has to meet higher insulation standards. It may be that the previous owners ignored Building Regulations. I think most people replace conservatory roofs because they get far too hot in summer rather than too cold in winter.

Cheers

Dave R

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