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Insulation

loft flat roof and building regulations requirements

Anonymous user 03/03/2024 - 3.46 PM

I have an existing rear loft bedroom that was “half” built outwards to the rear, with lower-than-average ceiling height. I hired a builder and have now had the loft built as it should have been originally built, including raising the ceiling/ roof height 200mm. The rear loft bedroom roof is flat with a pitch. The timber roofing joists are 47mm x 170mm with 18mm plywood decking above. The insulation should sit in between the joists. So, my questions are about the insulation. What kind of insulation or method would be best to install without adding insulation below the bottom of the joist (as to not to lower the ceiling)? I'm mainly concerned about lowering the ceiling as I just paid to raise the ceiling. Please let me know that the current building regulations requirements are? How best to achieve this without adding additional layers which would lower the ceiling? What specific insulation products to use? All ideas and suggestions are greatly appreciated! Thank you.

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4 Answers

Handimen (Home & Garden)

Rating: 4.8 out of 5
Tunbridge Wells
A couple of possibilities are to either: add insulation-plasterboard to existing ceiling !? (Which would only lower ceiling height by between 25 > 50mm, dependant on your choice)? Or to add to thermal efficiency as I have just done for another flat roof, is to fit “Wallrock KV600” to the ceilings. Although the material finish is only 4 > 5mm, the effect is surprisingly good. There are other more costly options, but either of the above would help reduce heat loss.
Answered8 October 2023
7

Romeo Llabani Plastering

Rating: 5 out of 5
Northampton
If you hired a builder to raise the roof/ceiling, then he/she should have known the requirements around insulation Anyway, Option one: You could add PIR insulation boards on top of the roof and follow up with ply and new cover. This is called warm roof and that is what your builder should have done in the first instance. This way you keep the ceiling height. Option two, would be to remove the ceiling (plasterboard I guess) then add PIR insulation boards in between the joists, but you'd have to leave 50mm gap from the roof membrane to the insulation (cold roof). Then add another 25mm of the PIR boards again followed up with the new plasterboard and skim. Although this can be optional, it will help with the thermal efficiency of the room. I can't comment on the wallrock KV600, as I haven't used it yet, but if it has worked for people, then why not (do your research) Hope you get it sorted
Answered8 October 2023
1

Anonymous user

The Synthesia/Kingspan is so thermally efficient it’s amazing and the soundproofing stunning installed in 1 day with minimal mess.
Answered8 October 2023
0

Alland Drylining and Construction

No reviews yet

Burgess Hill
If you are building to current regulations you will require celotex (other brands available) between the rafters and then a thermal board (plasterboard with celotex on the back) on the under side of the rafters to stop any cold bridging.
Answered26 October 2023
0