How do I find an independent assessor in the Melton Mowbray area

You pay cheap you pay twice. Domestic customers tend to go for the cheaper option. And grp is usually the cheapest option and can be obtained in any roofing store by anyone the instructions are in the tin it’s a diy material. If your having a roof done in grp quiz the installer test his knowledge on it . If he says they make boats out of it RUN. I’d always suggest either single ply pvc membranes as you have to be trained and approved to buy/ install this and most suppliers recommend an area rep to do a site visit to make sure the system has been installed correctly

Have you contacted the company who did it? They should come back an repair the roof really. I don’t do fibreglass for the whole reason they always leak an it’s a nightmare to set if not done in correct weather, also I only use felt bitumen

You are not alone, I have had to replace lots of grp flat roof due to poor workmanship, the problem is that it takes half a day course to become qualified!! So now your getting builders going on this grp course and suddenly they are flat roofers but they don't have any experience in flat roofing at all, I went to college for 2/3 years and have nvq level 2/3 in mastic asphalt, it is by far the best material to use on a flat roof or balcony , all these new systems say they will last for 25-50 years, its a load of rubbish, stick to tried and tested flat roofing systems like 3 layer felt and mastic asphalt you won't have a problem!!

GRP is an excellent product, I would likely rethink it’s poor installation. Flat roofs are always prone to problems no matter what the material, one is no better or worse than another. I would advise if possible to have a pitch roof with breathable membrane and suitable tiles or slate. Kind regards.