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Warm flat roof Eave height - Permitted development already commenced

Discussion in 'Building Regulations and Planning Permission' started by gbr9282r, 3 Aug 2020.

  1. gbr9282r

    gbr9282r

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    Hi all,

    I may have the worst luck ever... we are well underway with a small (albeit larger home extension). The neighbours and everyone being fantastic, no issues with anything... The foundations and walls are now up... even though the drawings sailed through the prior approval process, the eave heights aren't correct. As it's close to the boundary, they can't be over 3m. That's fine, but the warm roof insulation which overhangs the eaves and the strange 50mm gap (which i think you normally only have on cold roofs) takes it to 3.16m. 16cm over.

    if you look at the plan, the dip edge is to the sides, but that's already changed to be above the new doors. I don't mind that... The 2570, is the current ceiling height internally. The external ground level to lower rafter height, is 2800.

    My two solutions:

    If I we lay the 120mm insulation to in effect close the cavity, to cover the block cavity wall insulation, but not over the outer leaf of bricks, that gives me just under 3m exactly at the 'stepped down eaves... if you measure the eave height, as the regs say, from the face of external wall... There will be a slight step, which will make putting soffits on interesting...

    There is a slight overhang of the rafters, if you measure to the top of these, that is exactly 3.0m.

    Basically, if i need to overhand the insulation right across, I'll have to take a couple of courses of bricks out. to take the rafters down to the new height i've drawn on my plan and have a slightly different ceiling height in the new bit.

    I IMG_1185.jpg
     
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  3. DevilDamo

    DevilDamo

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    Assuming your existing ceiling height is 2570mm and the new extension has therefore been designed to match, wouldn’t it have made sense to have that ceiling slightly lower the existing?

    Can’t quite make out all of the above but you’re aware the eaves height of a flat roof is the top so your flat roof finish? What’s the distance from underside of ceiling to top of finishes... more than 430mm?

    Just a side note... rooflights shouldn’t really protrude more than 150mm from the roof finish either. In some cases, LPA’s have taken the height to the rooflight/lantern as the overall height :confused:
     
  4. Londoner2

    Londoner2

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    My extension height is well over the permitted allowed, no one has complained and after 3 years council can't say bo diddly
     
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    DIYnot Local

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