Hi guys, I have a flat roof on a small extension which needs redoing as the boards are well past it and the roof is now leaking. The set up of the current roof seems how it "used to be done", ie, plasterboard onto joists, no vapour control layer, some wool type insulation and then the decking and then felt, some other black stuff and some stones. Over time condensation has rotted the decking from the underside, the roof pools water when raining and it now gets through.
I have a few bits of help needed due to the circumstances but so as to not go all out to begin with I think the key decision on warm or cold roof, if you can help it would be great.
Please see the pictures attached, they are not to scale as i've drafted them on paper and pencil but they give a good idea of what i'm saying...
The first image is how I hoped the joists would run but they don't, they run horizontal across the extension like the 2nd picture. I have issues there regards ventilation should I need to do a cold roof but we'll come to that later if needed.
Ok, I initially opted for a warm roof using Celotex all in one boards and covered with EPDM, sounded really good. However, due to the extra height that would give put a bit of a downer on it due to the sloping neighbouring roof (adding complications on sealing that join at the end of the extension) and then also potential planning issues with the council.
Easiest option seems to just go for a replacement cold roof to keep the same height and same seal with the neighbouring roof but this time do the insulation and venting properly. However, i've cut a section of the plasterboard away to check the inside and I have a clearance from the top of the plasterboard of about 135mm. My question here is, am I screwed from the outset for a cold flat roof as i'll need 100mm insulation and then 50mm ventilation space and so with just 135mm i'll not be able to get the regulation approval from the council?
I have a few bits of help needed due to the circumstances but so as to not go all out to begin with I think the key decision on warm or cold roof, if you can help it would be great.
Please see the pictures attached, they are not to scale as i've drafted them on paper and pencil but they give a good idea of what i'm saying...
The first image is how I hoped the joists would run but they don't, they run horizontal across the extension like the 2nd picture. I have issues there regards ventilation should I need to do a cold roof but we'll come to that later if needed.
Ok, I initially opted for a warm roof using Celotex all in one boards and covered with EPDM, sounded really good. However, due to the extra height that would give put a bit of a downer on it due to the sloping neighbouring roof (adding complications on sealing that join at the end of the extension) and then also potential planning issues with the council.
Easiest option seems to just go for a replacement cold roof to keep the same height and same seal with the neighbouring roof but this time do the insulation and venting properly. However, i've cut a section of the plasterboard away to check the inside and I have a clearance from the top of the plasterboard of about 135mm. My question here is, am I screwed from the outset for a cold flat roof as i'll need 100mm insulation and then 50mm ventilation space and so with just 135mm i'll not be able to get the regulation approval from the council?
