blend to and extend existing GRP roof?

[pb2012]

Hi all,

Before I embark on something I'd like to quickly ask if it is ok to take an existing GRP roof and extend it over a larger area?

This would essentially involved cutting along the edge of the existing roof, then GRP'ing from that cut and over another few square meters, creating a bigger roof.

Can the point where old GRP meets new GRP be blended and weather sealed ok? Or does the join create a weak spot?

I'd rather avoid starting again with one big new roof.

Thanks!

 

[geraldthehamster]

In general, you can rough up existing GRP and bond new GRP to it. I've no idea whether there are particular issues with roofs though

 

[Nige F]

Can the point where old GRP meets new GRP be blended and weather sealed ok? Or does the join create a weak spot?



Thanks!

I don't know about blending it - I would think you'd end up with a bump of a few mm. which might then create a puddle.

 

[pb2012]

I don't know about blending it - I would think you'd end up with a bump of a few mm. which might then create a puddle.

That would be a problem as the join would be horizontal with water running over it, so yea there might be potential for a little pooling unless completely smoothed off. Hmm.

 

[oldbutnotdead]

Yes you can do it. You need to fix the new roof bit to the existing roof bit very firmly (plate beneath the join)- or if the drainage allows then use a rolltop trim to link the 2 together. Deal is- set deck of new bit level with deck of existing bit. Fit any trims etc that you need. Grind topcoat off existing bit (til you get down to clear laminate- not the end of the world if you get down to board but best avoided). Wash existing ground bit with acetone. Start new laminate from existing ground down bit extending across the join. Topcoat.

 

[pb2012]

Yes you can do it. You need to fix the new roof bit to the existing roof bit very firmly (plate beneath the join)- or if the drainage allows then use a rolltop trim to link the 2 together. Deal is- set deck of new bit level with deck of existing bit. Fit any trims etc that you need. Grind topcoat off existing bit (til you get down to clear laminate- not the end of the world if you get down to board but best avoided). Wash existing ground bit with acetone. Start new laminate from existing ground down bit extending across the join. Topcoat.

Useful instructions, thanks very much!