Shouldn't the roofers have top coated the glass fibre roof by now?

[DaveAF]

Hi.

My neighbour had a flat foof put on his extension in early September 2023.

He loves it but doesn't know much about glass fibre.

The builders put 1 layer of glass fibre matting on it 4 weeks ago but haven't topcoated it.

It's too late to get a proper bond after 4 weeks surely? 

Why would anyone wait so long to topcoat? 

 

Just wondering. 

Edited October 20, 2023 by DaveAF

[Conor]

Just needs a good rub down with fine sandpaper and it'll be fine. Topcoat in theory protects against UV damage, otherwise aesthetic. Looks like a pretty good job btw.

[SteamyTea]

9 hours ago, DaveAF said:

1 layer of glass fibre matting on

FFS

Just as well they have not put the top coat on.  1 layer is bugger all and will quite possibly cause problems in the not too distant future.

If they use the right kind of resins, adding extra layers and a top coats onto fully cured substrate is not a problem.

 

I will say that it does look a reasonable layup for 1 layer, nice and resin rich, which is a good thing.

[Conor]

11 hours ago, SteamyTea said:

FFS

Just as well they have not put the top coat on.  1 layer is bugger all and will quite possibly cause problems in the not too distant future.

If they use the right kind of resins, adding extra layers and a top coats onto fully cured substrate is not a problem.

 

I will say that it does look a reasonable layup for 1 layer, nice and resin rich, which is a good thing.

??

 

Any kit I've ever used has been a specific one layer chopped strand kit. I didn't know multi layer was a thing.

[DaveAF]

12 hours ago, SteamyTea said:

FFS

Just as well they have not put the top coat on.  1 layer is bugger all and will quite possibly cause problems in the not too distant future.

If they use the right kind of resins, adding extra layers and a top coats onto fully cured substrate is not a problem.

 

I will say that it does look a reasonable layup for 1 layer, nice and resin rich, which is a good thing.

Oddly enough after they repaired a minor leak yesterday morning they finally topcoated the roof. No extra layers of matting though, just a paint over with the topcoat. 

[SteamyTea]

1 hour ago, Conor said:

I didn't know multi layer was a thing.

2 layers of 450g/m² CSM would be normal, I would always recommend 3 layers.

 

As a general rule, 1 layer of 450g/m² matt is 1 mm thick and will take 900g of polyester resin.  If going onto a very absorbent substrate like OSB, then the first layer will take more resin.

Topcoat is around 350g/m².  This can vary quite a lot depending on the final usage i.e. aviation and walkways are treated very differently.

[Conor]

Glad I've only done a shed roof and a balcony then 🤣

[SteamyTea]

18 minutes ago, Conor said:

Glad I've only done a shed roof and a balcony then 🤣

Treat it as aviation, they usually fly off eventually.