Cracks at corners of flat roof

[geoff956]

Hi,

We have a GRP flat roof and cracks have appeared at the corners and some of the overlaps seem to have loosened.

As we know nothing about the subject we would be grateful for any advice. Pics. attached.

Many thanks in advance.

[nod]

I’d contact the installer 

Most will have issued a product guarantee

and may be able to make a repair  

[Jeremy Harris]

Looks like the preformed mouldings at the edges and corner weren't bonded to the GRP making up the roof when it was laid.  Could be for a few reasons, but I'd guess that the mouldings weren't properly cleaned before installation.  The chances are there may still have been some mould release residue on the surface of these mouldings, which has prevented them bonding together.

 

The fix will be to remove them and redo part, or all, of the roof.  The guarantee period on a properly installed GRP roof should be fairly long, at least 10 years, so as @nod suggests, first port of call would be to track down the guarantee and the installer and see what they have to say.

[epsilonGreedy]

12 minutes ago, JSHarris said:

Looks like the preformed mouldings at the edges and corner weren't bonded to the GRP making up the roof when it was laid.

 

 

Is it possible those corner mouldings are just that i.e. bits of plastic intended to shape the grp lamination at the corner of the roof? If so this is not a failure of bonding but a failure by the installer to wrap a continuous grp layup around the corners.

 

OP: What are the corner pieces made of?

[Jeremy Harris]

38 minutes ago, epsilonGreedy said:

 

Is it possible those corner mouldings are just that i.e. bits of plastic intended to shape the grp lamination at the corner of the roof? If so this is not a failure of bonding but a failure by the installer to wrap a continuous grp layup around the corners.

 

OP: What are the corner pieces made of?

 

They are often GRP mouldings, hence the need to clean them to remove any mould release.  There are examples of similar roof edge and corner mouldings pictured here, although from the look of those I'd say that CFS has switched away from the GRP mouldings and maybe gone for some other sort of plastic moulding (I've used the older style of CFS ones a couple of times, and they used to be GRP):  https://www.cfsnet.co.uk/acatalog/CFS_Catalogue__Roof_Trims_550.html

[jack]

46 minutes ago, epsilonGreedy said:

OP: What are the corner pieces made of?

 

Fiberglass. They're a standard moulding for this application.

 

[Edited to add:]

 

Crossed with @JSHarris

 

I ordered a couple of sorts of these trims from different suppliers when I did our balcony and they were all GRP.

 

46 minutes ago, epsilonGreedy said:

 If so this is not a failure of bonding but a failure by the installer to wrap a continuous grp layup around the corners.

 

Looking at it again, you may well be right. It looks as though the GRP mat perhaps wasn't continuous around the moulding. Really poor form if so!