UK Regs for Ventilation for my loft conversion

Discussion in 'Building Regulations and Planning Permission' started by da3533, 28 May 2021.

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1. da3533

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Hello

I am half way through my construction of our loft conversion.
There are four rooms in total, 3 of which have 2 windows in each and one has just one as it is smaller.

Building officer inspected and said the windows needs to be 1/20th of the surface area. So one of the rooms has a surface area of 10m2 which, according to the regs, must have a window of 1/20th... so 0.50 ... however, one of the windows in that room equals to 0.34... but there’s another window in the same room which equals to 0.36. Can’t we use both windows to added together to help make up 1/20th of the rooms surface area?

3. Nakajo

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Just to clarify, the BCO was referring to the opening part of the window, which isn't necessarily quite the same thing.

Part F certainly implies that compliance would be met by providing a wind*ow* with the requisite openable area, but I don't see why the BCO wouldn't accept your alternative. Ask them.

Last edited: 28 May 2021
4. da3533

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BCO didn't reject anything just kept asking me to calculate whether the window is sufficient to the surface area of those rooms.
1st he was checking if it enough for fire escape etc, but then he said I would need fire doors everywhere in the house as the windows are smaller than the ones you are supposed to use for fire escape.
then 2nd, he judging and thinking whether there's enough ventilation. it is a 10m2 room, with 2 windows.

also, all windows have trickle vents which is around 5,000m2. theres two for both windows...

Approved document F. Page 51: EXAMPLE CALCULATIONS FOR VENTILATION SIZING FOR DWELLINGS F1:
'Therefore, for a living room of 13.5 m2 floor area there should be a window opening area of at least 0.68 m2. This calculation should be carried out for all habitable rooms'

Does this apply to all windows in that room to help with the calculation?

BCO told me to calculate the surface area of the room and dived it by 20 and the answer will need to be windows minimum. for example room 1 measures, 3.0m x 3.5 = 10.5m2 / 20 = 0.52. 1 window in that room = 0.35 and the 2nd window is 0.39. if I had only window 1, I would understand,
but cant I use both windows to help?

Last edited: 28 May 2021
5. Nakajo

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Sorry. I cannot see what part of this my previous answer fails to address

6. da3533

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According to him and Approved document F. Page 51 - it is just any window or size, it needs to be a minimum size according to the surface area of any habitable room

7. tony1851

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I wonder if your BCO is a bit dim?

1. The aim of the regs is to provide satisfactory purge ventilation; just because it states window in the Guidance, doesn't mean two windows are not acceptable.

2. If your house is a two-storey dwelling and you are adding a loft, escape windows in the loft are not relevant.

9. da3533

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He is, everytime he visits he tells me to do other things such as jiffy hangers etc when these should have been notices on the last 5 visits he did...

2. it is a bungalow, I am converting the loft. but having fire doors should be sufficient for fire if the windows are NOT accessible during a fire right?

Last edited: 28 May 2021
10. ^woody^

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Ventilation volume/area is per room, not per window. There are other options to ventilate apart from windows.

11. da3533

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What about fire escape? he said because you cant fit through the windows, all the doors including existing doors downstairs need to be replaced with firedoors... this makes sense but is it the case?

12. ^woody^

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Yes, the window openings should conform to the means of escape guide, else if the BCO is giving you an option to relax that and compensate with a protected escape route, then you need to consider that. You should also check if he will require enhanced fire detection with detectors in rooms.

13. da3533

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each room has 2 windows, 1 of which measures:
56cn x 68cm width
this size enough? it opens up wards, top hung, 'V' -- but said the hinges may need to change as when it opens, it obstruct someone from getting out...

protected escape route, need to be outside as it is a loft conversion...

Last edited: 28 May 2021
14. da3533

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my window 56cm Height x 68cm width:

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