Grp pooling and flaking

swebb99

swebb99

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Hi,

I had an extension done 5 yrs ago with a grp roof (Flexitec) and a couple of sky lights. It isn't leaking however it has always pooled just by the drip edge (not sure if that's the correct term) and was getting fairly filthy. I went up to clean it and realised that most of the surface has micro cracks in it, especially in the areas where there is pooling.

I've tried to contact the roofer and just get various excuses about why he hasn't turned up to check it out.

So I've got another recommended roofer to take a look and he said the top coat wasn't mixed correctly and the edges weren't rebated into the osb which is the main issue with the pooling. He also mentioned he wasn't too happy with the fall and thought it was on the limit which wasn't helping with the pooling and may be a reason for the dirty roof.

He said the options were, either clean, sand down, acetate(?) and cut edges out and refit properly, recoat. Or osb over existing roof with more drop and grp on this

Thoughts ? Any other options ?

Thanks in advance
 
Without pictures it’s hard to see why the topcoat is flaking or cracking, water and pooling on a GRP Roof should not be an issue. The same resins and topcoats (albeit slightly adapted) have been used to make boats for years so issues like this should be ok.

OSB over the roof and recoat, it’s an outdated method and I think against new fire regulations anyway. Not to mention the most expensive option.

The cheaper options would be to sand back and re-apply a new layer of topcoat fixing the issue with the trim or use an overlay system that will bond to the existing fibreglass roof and build up the ponded areas.

Get some more quotes from other roofers in your area and see what they say.
 
Here are a few shots. I had a walk around on the roof and the fibreglass doesn't appear to a delaminated.


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Thanks for the pics, It could be at the time when the roof was installed that they either applied the topcoat too thick or the main laminate was not sufficiently cured.

For roofs like this where the cracking is not contained to just one area we would use a flexible overlay system like the Overcoat roofing system or Fix-r which is totally DIYable if you want to tackle it yourself or sand the entire roof back and apply more Topcoat.
 
Thanks for that's. If sanded back would it need the same top coat as the original (flexitec) or would most grp top coats be suitable?
 
Ahh bugger it's Flexitec!!, I missed that in your original post. This system is a bit of a bitch to fix in that instead of just being able to sand it down and re-apply a layer of topcoat, the resin and topcoat are the same product so the company will say that you'll need to re-apply the full system again (resin + glass + resin) and will not support just putting someone else's topcoat down or just one layer of the flexitec product even though it's polyester based.

This puts the price up considerably as you or the contractor will need to purchase the entire system again, so overcoating might be the easier and cheaper option if that's a consideration.
 
Rufus Raintight said:
Ahh bugger it's Flexitec!!, I missed that in your original post. This system is a bit of a bitch to fix in that instead of just being able to sand it down and re-apply a layer of topcoat, the resin and topcoat are the same product so the company will say that you'll need to re-apply the full system again (resin + glass + resin) and will not support just putting someone else's topcoat down or just one layer of the flexitec product even though it's polyester based.

This puts the price up considerably as you or the contractor will need to purchase the entire system again, so overcoating might be the easier and cheaper option if that's a consideration.
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I'll be getting a different roofer in. Not the original guys who applied the flexitec. Are you saying that you can't use a different top coating because it won't adhere chemically after sanding or that flexitec won't back doing that due to warranty.

I'm not really tied to it with a warranty because that's only good if the original roofer is reused and I've lost trust in them anyway.

Is overcoating when osb is screwed on top of the existing grp and a new grp system is used. Or applying a top coat only. ? Sorry for being a bit confused I'm not fully up on all the terms.
 
Yes, so they will say another Topcoat won't stick to their existing Flexitec product and the only way to fix it is to buy the system again. It's a polyester system so a topcoat should stick but Flexitec does not recommend it with or without the Warranty.

An overlay system is a liquid roofing product that can be applied directly to the existing surface either with or without a primer. In your case, you would clean the roof, removing all the muck and mess. Make sure the roof is dry and then apply the resin system directly over your existing GRP Roof.

I don't like to put links on here because it looks like I'm advertising but here are a couple of systems I've worked with in the past;

Overcoat - https://www.overcoating.co.uk
Fix-r - https://www.sigroofing.co.uk/roofingproducts/fix-r/

These systems are hybrid polymer or polyurethane roofing systems and are not like the cheap repair or patch systems that you find in builders merchants (Acrypol, Roof paints etc...)
 
Sorry to ask for more info. So from what you have said if I don't go down the liquid rubber path then if the roof is cleaned correctly a normal grp type top coat should be fine but Restec who sell Flexitec wouldn't be ok with this which I would be fine with I think

Also as I mentioned the roofer I spoke to is concerned about the drop and the drip edges not being flat. He is going to also quote on installing new osb on top of the existing roof with a better drop and a grp finish. My concern with this is that I'm not clear if this is a reliable common method and I'm also concerned that the existing roof has detailing below the skylights and around the sewage pipe running down through the roof. This strikes me as tricky to work with if trying to recover.

He is also giving an alternative quote for cleaning, applying a top coat , oh and removing and rebating the drip edge correctly, however from what you mentioned about flexitec I'm not sure that is a good idea as cutting into it and then fiberglassing back on to it might be an issue.

Maybe I'm just over thinking all of this!!!
 
Hi,

If you called Restec they would tell you that just applying a new layer of topcoat onto their system wouldn't work and they do not recommend it. Flexitec uses the same resin system for both base resin and topcoat but it's a hybrid polyester resin and not the same as a traditional GRP Roofing system.

If you applied one layer of the Flexitec resin system to your roof they say it would work in the interim but then after a while, it would start peeling. They will tell you that the only way to fix the issues is to purchase the entire system again, sand back the existing top surface and apply resin + glass + resin which is totally overkill and a good reason for contractors to only use flexitec if they are overlaying onto an existing substrate like felt, concrete etc....

I would get some more quotes from roofers in your area explaining the issue with the Flexitec, As this product is readily available to purchase in builders' merchants without training I bet they might not even know about this and just see it as a standard GRP roof.

The cheapest route would be an overlay system as described above, they can be bonded directly to the existing surface and are so easy and quick to apply.

Apologies for the long-winded replies, this should be an easy problem to fix with the existing Flexitec system, but apparently not...
 
Thanks for the response. It's a shame using flexitec is causing this to be a pain. Two roofers have now told me they would clean the roof and put a top coat on, however this doesn't seem to be an option which is a pain.
 
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