GRP Roof issue

donmaico

I had it installed over an extension about 13 years or so ago and the issue regards a puddle of water that develops after rainfall and which tends to stay as it can't drain away due to a roof light which stands in the way. I was advised that such roof puddles if allowed to remain can damage the GRP so I wondered if is possible to lay extra GRP over the existing area so the water can drain either to the left or right?    Thanks

Mr.Generous

I'd be tempted to use some roofing bitumen and paint a square, but stick a load of 6mm Granite roofing chippings into it so all you can see is the granite. This will build the height up enough to clear the puddle. Probably only needs to be half an inch thick. make sure the roof can take the weight, but any roof should be able to handle that.

donmaico

Mr.Generous said:

I'd be tempted to use some roofing bitumen and paint a square, but stick a load of 6mm Granite roofing chippings into it so all you can see is the granite. This will build the height up enough to clear the puddle. Probably only needs to be half an inch thick. make sure the roof can take the weight, but any roof should be able to handle that.

seems like a good idea but would it sick to GRP particularly as wood tends to expand and contract ?

Kiran

How deep is the ponding and how long does it last for? Small amounts of ponding on GRP roofing isn't likely to cause an issue, in the same way that is doesn't on hot melt. I can't tell from the photo, but is the roof covered in algae/moss/general green slimy stuff? If so, cleaning the roof off with alleviate the ponding. Other than the upstand at the back I couldn't tell that was GRP, so a good clean might help out.  

donmaico

Kiran said:

How deep is the ponding and how long does it last for? Small amounts of ponding on GRP roofing isn't likely to cause an issue, in the same way that is doesn't on hot melt. I can't tell from the photo, but is the roof covered in algae/moss/general green slimy stuff? If so, cleaning the roof off with alleviate the ponding. Other than the upstand at the back I couldn't tell that was GRP, so a good clean might help out.  

the ponding has now gone after 30 or so hours of dry weather. I don't think its particularly deep although the roof light does prevent run off to some extent, There is no algae or moss present although i it could probably do with a general clean up. Thanks. for the reply

Mr.Generous

donmaico said:

Mr.Generous said:

I'd be tempted to use some roofing bitumen and paint a square, but stick a load of 6mm Granite roofing chippings into it so all you can see is the granite. This will build the height up enough to clear the puddle. Probably only needs to be half an inch thick. make sure the roof can take the weight, but any roof should be able to handle that.

seems like a good idea but would it sick to GRP particularly as wood tends to expand and contract ?

GRP? Glass reinforced plastic - does that expand? I wouldn't have thought so.

noitsnotme

GRP is fibreglass isn’t it?  Something that millions of boats are made of!  Would be odd if a bit of standing water could damage it.  Or is GRP used for roofing different to that used on boats?

Spinybif

GRP boats do absorb water by osmosis when sailing in fresh water hence the recommendation that they should be removed and allowed to dry out regularly (over winter). 

noitsnotme

Spinybif said:

GRP boats do absorb water by osmosis when sailing in fresh water hence the recommendation that they should be removed and allowed to dry out regularly (over winter). 

Interesting, I never knew that, thanks.  I only have experience of sea going boats.