Help with cracking on Fibreglass flat roof

[Gary Daines]

Hello

Looking for some advice with my fibreglass flat roof

it was installed in the summer of 2018 and I’ve recently noticed some cracking

I’m unsure if this is only on the top surface of the roof or not but so far I haven’t seen any leaking to the floor below

what I’m unsure about is whether this is a big problem (or will lead to a big problem) or whether it’s just the way they age over time and that this won’t lead to leaking on the surface below

any help would be appreciated and I have attached some pictures

unsure whether I need to be contacting the contractor to come to repair a section or relay the whole thing or not

I think they used a ‘Cure it’ GRP kit

thanks very much

 

[oldbutnotdead]

Looks as if they put the topcoat on a bit thick and it's got too warm when curing. From the way they've done the flashing they aren't professional GRP roofers (where the deck butts up to a wall you form an upstand as part of the roof, then cover flash over that upstand). What's the different coloured patch about (top of the last pic) - if there's been a leak and someone has used bitumen backed felt to repair it that won't do the GRP laminate any good at all.
EDIT Yes it will cause problems. The actual laminate isn't waterproof (the topcoat is) so those cracks will let water into the laminate which will eventually get into the deck and turn it into porridge.

 

[Gary Daines]

Hi

thanks very much for you reply

so am I talking a localised repair? Is that possible? Or in this situation can you only redo the whole thing?

the area at the top is where there was some old fence posts laying across the roof for a few months (that had some moss surrounding them, hence the outline) - so it’s the same top coat, just a bit of a different colour maybe because of the sun

in terms of upstand, under the flashing there is a long triangular piece of wood that the coating has gone ‘up’ and then the flashing is on top

is that the kind of thing you meant?

thank you

 

[oldbutnotdead]

Yeah, you can do it in 2 ways;
1 get a small tin of topcoat & catalyst and a litre of acetone
2 clean the roof (cloth/warm water clean, get rid of as much cack as possible), let it dry
3 grind or sand the cracked bits down (flap disc on an angle grinder works well) so you can see clear resin and mat.
4 wipe the dust off then liberally wipe the ground bits (and a margin around them) with acetone.
4a let acetone dry, make sure there's no risk of rainfall.
5 mix topcoat, apply a thickish coat (1mm max) to the ground bits, allow to cure (hour or so).

Option 2 is Acrypol - again grind the cracked bits off but don't go full depth into the resin then apply a good dollop of Acrypol to the ground bits.

Your flashing- there should be a gap (10mm or so) between deck and walls to allow for expansion/contraction. Upstand should be 100mm, so should cover flashing. Your fillet could become overwhelmed in a downpour (unlikely on that size roof but why chance it).
The flashing to the rendered wall- the cover looks far too short, same potential problem.
Is there a decent drip edge to the gutter?

 

[Gary Daines]

Ok thanks very much

Have attached a picture of the gutter side

The repairs could be above my skill/knowledge so will speak to initial contractor and see what he says first

If it can be a localised repair maybe that’s better

my concern of course is that these are just the first areas to show a problem and others will follow - but will see

 

[oldbutnotdead]

Well that's a novel setup- at least they've done the grp edge properly. Do you get any problems with rainwater overshooting that gutter (or bouncing out of it)? .And (just curious now) what are those two vertical bits of box section about?

 

[Gary Daines]

No, haven’t noticed any issues with water overshooting the gutter, it seems to run into it fairly steady

the boxes are fence post shoes installed at the same time at the fibreglass roof with fence posts (I want to in time install some fencing so I can have some pot plants out there that don’t blow/fall off the roof)