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I'm in the process of building an extension which has a metal roof (probably Greencoat PLX) specified. I'd like to kick the cost of the metal roof down the road a bit and was wondering if I can install Fibreglass coating now to make the structure weather tight and lay the metal roof on top of it at a later date? In short, can you lay a metal roof on top of fibreglass (with structural underlay) or is this a no-no?

Hi all, I was wandering if anyone could help me with suggestions as to how to marry up my new warm roof build up with my neighbour’s property? The issue is that my roof was installed about 50 years ago and since then my neighbour’s property has been extended meaning there is no access to the existing fascia etc. to make this even more fun, I am going to add a warm roof build up of 170-175mm (Velutrix, 150mm PIR, 18mm OSB, GRP over existing deck). This brings the new height to around halfway up their fascia board. I have my neighbour’s consent to take my roof to meet their wall and close the 40-100mm gap which currently exists but I would appreciate any thoughts as to how best to do this while allowing the GRP to run high enough… ie. Should this be behind their fascia board? I have added a picture for reference - the gap is below the gutter line although it does not really show very well. Any input would be greatly appreciated! Many thanks in advance…

Hey all, What are the going rates these days for flat roof installation with GRP, if the sub base has already been prepped ready for GRP install? I have flat roofs to main roof, terrace areas. Cheers C

Hello, I'm having kitchen extension built with a flat roof that will have a long 1.5m overhang. The roof will have GRP applied meaning an ugly GRP edge trim on top of the fascia. I would like the front of the roof to be completely flat like here: Is this possible without breaking any building regulations ? Any suggestions/recommendations would be greatly appreciated. Thanks.

So.... Old roof off this week, firings sorted so our roof has a fall on it and the professionals arrived today for the GRPing, thank god it's dry. On site at the moment and just had a sneak peak. We are so pleased with this compared to previous. This is the fall, not sure how the builders are going to deal with the exposed wood yet. Credit to the guys who were on site before 8am.

I had a felt flat roof replaced a few years ago by GRP. I have noticed that water is curling up behind the edge trim and round the back of the guttering onto the fascia. Some of this is making its way over the top of the fascia and into the roof structure. I think the crux of the problem maybe that the gap between the inner lip of the edge trim and the fascia is only circa 10mm. This means the gutter edge in places is mm away from the edge trim. I have removed the gutter in case it is too high and impacting the water flow, but it makes no difference. How do I solve the problem? Packing out behind the edge trim would increase the gap, but from testing it with a hose, it is not the solution as I gain maybe 7 or 8mm. Fiddly, but the best idea I have come up with is using a self adhesive flashing like AluFlash and stick it to the inside of the edge trim over the batten under the roof lip and down a portion of the fascia before trailing it in the gutter. Apart from having the edge of the roof refitted, is this my best solution or can anyone think of anything else I could do? Thanks Steve

To those who commented on our GRP, this is not an update. The next installment to that will hopefully be at the end of next week when the crap roof will be off and a proper company coming in to sort after we insisted on an insurance backed guarantee. I shall update then, watch this space! Flat roof aside..... All our new extension had insulation laid and our existing flooring excavated for insulation too. We had the UFH pipes laid and there was A LOT. And then screed laid which is suprisingly even and flat using TG Cemfloor – a liquid self-levelling screed. Needless to say they did a better job of this than the roof. And part of the in roof solar frames have also gone up. Our builders found these up the loft when taking down the old ceilings. Unfortunately empty! Someone had a good party ?

I'll start with the GRP roof but I'll dedicate this whole blog entry to which I will deem the God-awful Rubbish Period. This probably seems like I'm over exaggerating but there's just been a lot of things combined with work, personal etc and I have really been feeling the pressure. Intially, as they started laying the fabric the GRP looked OK but, despite what I would say is perfect conditions for the GRP going on from what I know through reading on here we, were appalled by the quality of the work. Without bombarding this blog with pics unless you really, really want to see them, just take my word for it, it was bad! I believe I this was subcontracted but as we have not been on site I think it's been done by the builder themselves. Needless to say I was not happy so met with the builder who muttered something about weather and acknowledged it was poor. There has been some improvement but I can't say I'm entirely happy but I believe this will be rectified, hopefully. I also raised the issue of the rooflight upstands not been GRPd to the roof and something is happening with lead flashing so I'm hoping that will be rectified too. Here is the current GRP as it stands, comments welcome because I don't know if I'm being over picky but I want to be prepared for meeting the builder this week so please give me your opinions. Roofing aside, thanks to the people that contributed to the thread on our ASHP and solar @PeterW and @ProDaveothers as I really feel I would have had a complete meltdown. For some reason the idea of fitting a PV immersion controller seemed to cause all sorts of issues and it's literally blown my mind trying to explain to people that should know more than me how to do it and what is needed. And my final rant, how is it despite giving delivery drivers instructions they still turn it in an articulated lorry the size of a double decker bus.... er no you will not that over a canal bridge! Took delivery of a bathroom suite after it was pump loaded over the bridge with the lorry blocking the farm who were not happy and finally unpacked it to find the whole lot was damaged. Can't get the same items now as they are out of stock but in some good fortune the bathroom company decided it was far too much hassle to collect them again so let us keep them and refund the money so we can flog them to try and pay for an alternate suite. We did finally get all our 12 panel GSE 3.84kw PV system and immersion controller for under £2300 which has now been delivered which is a relief. If the builders make as much of a dog's dinner of fitting this as they did of the GRP I'll have an absolute breakdown ?

All, today's torrential downpours have resulted in a leak in my living room roof. When the OSB boards were originally put down, it started to rain before we could get them covered. The roofer did his best to dry the boards out and put down the GRP roof. He did warn us it was not ideal, but we were desperate to move in, so I told him to just go for it. 3 years on and the top coat is flaking badly and the roof has started to leak. I intend to go up tomorrow morning, clean up the roof and put down some repair product that my brother swears by. Has anyone got any advice on how to clean up the flaking topcoat as it is really tough stuff and cannot simply be pulled away? Thanks in advance, Narinder

I know there's a few boaty/planey (technical terms!) types on the forum so I had a quick question regarding bonding fibreglass to PVC pipe: As a general rule its supposed to be a "no" as fibreglass doesn't stick that well to plastics but in the past I have got away with it by roughing up the pvc and giving it a good clean with acetone. I've also used 3M 5200 in the past but it takes bloody days to dry properly and is a messy horrible product. I wondered if anyone had used any other methods?

The super sharp lines of @Trw144 roof line (See here: has prompted me to make a design detail decision about the flat roof on my dormers. My died in the blood old boy roofer friend says "Got to have 50mm overhang from the face and sides of the dormer. Nothing less". But that's not exactly going to produce a contemporary sharp looking roof is it? My intention is now to use GRP/fibreglass with the minimum depth of edge I can get away with. Which is my first point of annoyance as all the pre-formed edging strips are min 100mm depth. So what's peoples thoughts on the overhang issue? Can it only be less if you have some form of internal gutter to stop run off?