You make two applications - first one for the extension and all the other works. And once that work is completed and signed off, make another application under the building notice route to install the roof lights.
25% Floor Area Rule...?
- Thread starter Nail_it
- Start date
You make two applications - first one for the extension and all the other works. And once that work is completed and signed off, make another application under the building notice route to install the roof lights.
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(quote .Mikric, No under Nottingham).
Shame, I know that the BC manager at Rushcliffe is the author of a fantastic spreadsheet that allows BC to do their own trade off calcs.
Why not explain your issues with your BC, they might not have a problem with it or perhaps they use Rushcliffes calculator as they are neighbours so to speak.
1.7m2 over isnt much they should agree to a minor upgrade somewhere without calcs, but if using BnQ doors check the u-values of the glass before you buy.
Shame, I know that the BC manager at Rushcliffe is the author of a fantastic spreadsheet that allows BC to do their own trade off calcs.
Why not explain your issues with your BC, they might not have a problem with it or perhaps they use Rushcliffes calculator as they are neighbours so to speak.
1.7m2 over isnt much they should agree to a minor upgrade somewhere without calcs, but if using BnQ doors check the u-values of the glass before you buy.
Cheers Woody.
Mikric,
The missus is set on all this glazing, so I'm not sure that I want to take a chance of getting appointed with a flexible BCO.
Thanks all the same. I think next time I move, i'll make sure its to Rushcliffe.
One more thing guys, the plan was also to install a back door. Obviously if the door is glazed/part glazed this will effect the glazing area calcs. Is there any effect of installing a non-glazed pvc/timber door ?
Mikric,
The missus is set on all this glazing, so I'm not sure that I want to take a chance of getting appointed with a flexible BCO.
Thanks all the same. I think next time I move, i'll make sure its to Rushcliffe.
One more thing guys, the plan was also to install a back door. Obviously if the door is glazed/part glazed this will effect the glazing area calcs. Is there any effect of installing a non-glazed pvc/timber door ?
The 25% rule applies to doors & windows glazed or otherwise.
I think you're really worrying about things too much.
The 25% rule should not be seen as a barrier to complying but simply an alternative method of achieving compliance when a large amount of glazing is required.
I think you're really worrying about things too much.
The 25% rule should not be seen as a barrier to complying but simply an alternative method of achieving compliance when a large amount of glazing is required.
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Specifically, the 25% rule applies to "openings" in the wall or roof and not doors or windows or type of doors, windows or frames within the openings
Roof sun-pipes are not normally counted, so in some circumstances these may be an option if close to the limit and you don't want to do any SAP calcs
Roof sun-pipes are not normally counted, so in some circumstances these may be an option if close to the limit and you don't want to do any SAP calcs
Totally agree, well said.
As already said, the prescriptive method allows you to have 7.8m² of doors, windows and roof lights (including frames). I think this assumes a typical U-value of 1.8 (band C?). So you have to keep below 7.8 x 1.8 = 14 W/K for doors and windows. If you go for better windows with a U-value of 1 W/m²/K say, I suspect you should be able to increase the area to at least 14m². (You get a bit more because you're also saving heat lost from 6m² of wall and roof.)
For your proposed windows, it might be enough to get their average U-values down to 1.8*7.8/9.1 = 1.5
In other words, work out the heat loss for an extension built to regulations using the prescriptive method and with the worst acceptable U-values. Then show that your design is no worse than that. If that is not enough, you can start stirring in things like solar panels to offset the extra heat loss. With more glazing, you get passive heating and that can be included too. (Some say that better passive heating is the reason we still have double glazing while triple glazing is standard on the Continent.)
For your proposed windows, it might be enough to get their average U-values down to 1.8*7.8/9.1 = 1.5
In other words, work out the heat loss for an extension built to regulations using the prescriptive method and with the worst acceptable U-values. Then show that your design is no worse than that. If that is not enough, you can start stirring in things like solar panels to offset the extra heat loss. With more glazing, you get passive heating and that can be included too. (Some say that better passive heating is the reason we still have double glazing while triple glazing is standard on the Continent.)
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