Our house has a GRP flat roof. 10 years old but with next to no insulation so pretty inefficient re heating. Had a couple of small leaks which I found (I think) and fiberglassed over and all seemed well.

But with all the snow lying on the roof, we now have (in the same places) several steady drips. (Maybe my fiberglassing was poor?)

Company that fitted the roof aren't the slightest bit interested despite a 'guarantee'.

We'd ideally like to have the roof made 'secure' plus it'd be great to add some insulation … but without ripping the whole lot off and starting afresh. (I Googled a company that lays a rubber layer on top of existing roofs and can add an insulation layer).

Any advice? Am I right in thinking that I can glassfibre the leaks (assuming I can find the holes)?

Ta

if you can find the leaks maybe, but can you find the leaks, water can travel, so you can be convinced a leak is in one place but it is somewhere else. And are you sure it is a leak and not condensation?

more than likely as mrmo said condensation

though grp can break down over time and if there were resinless voids in it then water can get through if the skins over the voids are cracked

If its 10 years old then it should have had insulation surely?
Why not just batten out over the grp, add some rigid insulation and then just sarna over the top?

I've just got planning and building regs passed to upgrade my flat kitchen roof to a 15 degree tiled pitch. The right tiles can go to 12.5 degrees these days, proper insulated warm roof.

I Googled a company that lays a rubber layer on top of existing roofs and can add an insulation layer

Can't offer any advice only to tell you the following for reference –
we had this system put on our flat roof – an aging concrete thing… IIRC it was 4 x 2 battens attached to the existing roof, insulation, 3/4 ply then the 'liquid plastic' membrane on top.. Total about 15 sq mtrs @ about £2750… seems ok – so far 😉

there is a comapny named Sarnafil (might not be, but name is very simialr). admittedly i haven't dealt with them in the last four years but they seemed to do a good product.

If installed correctly sarna works very well.