Subfrequenz Posted July 24, 2021 Share Posted July 24, 2021 Hello all! I'm looking to re-felt an existing flat roof on a town house in Crawley. It hasn't been touched for a good 30 years, although it has been repaired so is leak-free. I had a telephone chat with a duty surveyor for Sussex Building Control who seemed to suggest that a building control application isn't needed This is because the deck and below isn't being replaced, only the top felt, with additional warm roof being added on top of the existing structure. Would be good to know of anyone else's experiences! Thanks. Below is a rough outline of what we are planning. * Remove all existing roof covering to bare timber deck * Apply SA bitumen primer to whole of roof * Apply first layer of torch safe vapour control layer * Fix 50 mm timber kerb around whole of outside edge * Lay 50mm flat roof insulation boards * Create new timber outlets to downpipes * Apply torch on sanded underlay * Fix 100mm GRP drip trims to outside edge * Apply Technotorch mineral capsheet to finish Link to comment Share on other sites More sharing options...
Mr Punter Posted July 24, 2021 Share Posted July 24, 2021 If there is no insulation in the roof you may want thicker insulation boards but this can impact on the eaves and abutments. Link to comment Share on other sites More sharing options...
Subfrequenz Posted July 24, 2021 Author Share Posted July 24, 2021 9 minutes ago, Mr Punter said: If there is no insulation in the roof you may want thicker insulation boards but this can impact on the eaves and abutments. Cheers. Do you reckon this is exempt from building control? I appreciate if the roofer discovers major issues with the joists and boards then it will probably be needed. Link to comment Share on other sites More sharing options...
Mr Punter Posted July 24, 2021 Share Posted July 24, 2021 You would need to ask them. 50mm insulation won't quite do it for existing but it will still make a fair difference. Link to comment Share on other sites More sharing options...
tonyshouse Posted July 25, 2021 Share Posted July 25, 2021 You will need to comply with part L1b of the building regulations in particular the U value requirements even if not formally controlled Link to comment Share on other sites More sharing options...
Olf Posted July 25, 2021 Share Posted July 25, 2021 On 24/07/2021 at 15:54, Subfrequenz said: I had a telephone chat with a duty surveyor for Sussex Building Control who seemed to suggest that a building control application isn't needed Get that in writing to avoid any poroblems in the future. I'd say that because you're affecting thermal properties of the roof, that would need to be done to current standards, though the workaround can be using extra wool in the attic. Link to comment Share on other sites More sharing options...
Temp Posted July 25, 2021 Share Posted July 25, 2021 (edited) @Subfrequenz Google found.. https://www.nfrc.co.uk/docs/default-source/form-protected-documents/homeowners/householders-guide-to-flat-roofing-2015.pdf Quote PLEASE NOTE: Refurbishment of a flat roof is likely to be reportable to the Local Authority Building Control (LABC) and approval must be sought unless the contractor is a member of CompetentRoofer (see page 13). Part L of the Building Regulations may require additional thermal insulation to all re-roofing projects where the roof underneath is heated e.g. a kitchen or bathroom. The required ‘U’-value is 0.18W/m2K. You should discuss converting to a warm-decked roof with your contractor and LABC. Here are some examples... snip.. Page 13 says.. Quote CompetentRoofer - the Government-licenced Competent Person Scheme, that allows self-certification under the Building Regulations of roof refurbishments within England and Wales. Works carried out by CompetentRoofer members automatically receive the Building Compliance Certificate and are warranted for a period of ten years. Worth reading whole document before getting quotes. The situation appears similar to that for replacement windows or notifiable electrical work eg The "competent scheme member" will notify Buioding Control for you. Edited July 25, 2021 by Temp Link to comment Share on other sites More sharing options...
Olf Posted July 26, 2021 Share Posted July 26, 2021 14 hours ago, Temp said: The situation appears similar to that for replacement windows or notifiable electrical work eg The "competent scheme member" will notify Buioding Control for you So it will reduce hassle and cost with BC application, but will not remove the need for more insulation than planned 50mm. Unless of course you find a 'competent builder' happy to issue a certificate stating that the job is ok, even if it isn't. 1 Link to comment Share on other sites More sharing options...
Temp Posted July 26, 2021 Share Posted July 26, 2021 +1 If you have existing insulation between rafters and only put 50mm above them that would leave the top of the rafters close to the cold side and without ventilation = possible condensation risk. Ideally you need more above the rafters and less below or keep it as a ventilated cold roof. Link to comment Share on other sites More sharing options...
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