How to fix decking to fibreglass flat roof

[eltommos]

Hope someone can offer help with this one. I want to lay a 3m x 5m wooden decking on top of fibreglass flat roof. I don't want to drill holes through the fibreglass flat roof because of potential water leaks. I'm thinking of gluing the decking joists directly on to of the fibreglass. I could attach exterior plywood squares to the underside of the joists to increase the strength and spread the load. The decking has to be strong enough to support a 3 sided stainless steel and glass balustrade which will be attached to the walls of the house on 2 of the side ends. The site is subject to strong winds and I want to be sure that the whole structure is strong and safe and doesn't blow off on to the neighbours BMW. Would be grateful if someone could suggest a suitable glue to use. Or any other ideas of fixing the decking down without drilling holes in the flat roof. Appreciate your help.

 

[merlin50]

do not use glue use fiberglass, simples.

 

[Blagard]

Just don't do it at all.

Unless the deck is part of a building control approved scheme I would not expect the roof to be suitable for what you are thinking of doing.

 

[freddiemercurystwin]

Unless you have Planning Permission and intend getting Building Regs Approval I'm loathe to comment further, if you are doing it properly please reply accordingly. What you are doing can be done but is fraught with difficulties to overcome.

 

[Static]

I think youll need one of these:

The chances are the roof isnt even designed to take one person walking on it let alot the weight of a decking and 3-4 people..

Redo the roof timbers with something more suitable to support a flooring.

 

[maltaron]

You will need planning permission cause its over 300mm high, but I think it is a big no-no from the construction point of view anyway.

 

[eltommos]

Unless you have Planning Permission and intend getting Building Regs Approval I'm loathe to comment further, if you are doing it properly please reply accordingly. What you are doing can be done but is fraught with difficulties to overcome.

Many thanks, Freddymercurystwin, for your reply. I do have full planning approval. The flat roof construction is a recent extension. The roof joists are 200mm at 450mm centres with 25mm plywood on top. I think gluing down with fibre glass is a good idea - I've seen this before. The balustrade will be supplied and fitted by a reputable national company and they will install to building reg standards. Would appreciate your further comments.

 

[freddiemercurystwin]

You are likely to need to double up the joists as well as other structural works and you'll very likely need to employ a structural engineer too, handrail designers are good at designing their handrails but not so good at determining whether what they are fixing too is up to it though and more importantly are unlikely to be qualified or insured to do so. I have done this twice now and each time the timber joists were doubled up. On a garage I did the handrails were side fixed into the end of the joists rather than surface fixed. The decking that sits upon the roof will just sit there under its own weight and is the least of the problems to be encountered tbh.

Untitled

• freddiemercurystwin
• 23 Aug 2010
• 1

Untitled

• freddiemercurystwin
• 23 Aug 2010
• 1

 

[julie scott]

Did you find a way to fix your decking to the fibreglass roof? I have the same problem now.

 

[freddiemercurystwin]

Did you find a way to fix your decking to the fibreglass roof? I have the same problem now.

As mentioned, the deck will sit there under gravity quite happily, no need to fix down.

 

[catlad]

Fibre glass is very flexible in that sense, you could fibre glass some timber to the deck and then screw into that.

 

[eltommos]

Hi all - I successfully managed to install a stainless steel and glass balcony (around 10 years now) including decking on to my flat GRP roof. I had planning permission plus building reg approval. I bolted the stainless steel tubular frame structure onto wooden beams (aprrox cross section 5'' wide x 8'' high) which were bonded to the GRP roof using Sikaflex 221 polyurethane adhesive. To allow water drainage, I left gaps between the wooden beams and GRP roof surface. All still looking great!! Don't take any notice from some of the above comments - some replies are plain stupid and not worth reading - they must be bored or something?

 

[stephen stranks]

Hi Eltommos
could you give me a little more details how you managed to do this. This is exactly what I was proposing to do.