Do I need these?

[bluebaron]

Hi,
Doing a warm roof and someone suggested I need these fittings?
https://www.ukflatroofing.com/insul...or-plywood-deck-170mm-insulation-box-100.html

I understand if the top deck is standard osb but if I use T&G osb do I really need them?

it will be nailed around the edge 6mx4m.

thanks

 

[RandomGrinch]

Hi,

As per the information on the web page, they recommend 12 fixings per 1200 X 2400 board.
I may be wrong - am only a DIY-er , but that seems a decent number of fixings to avoid uplift.
I don't think it would be the best idea to fix the boards just around the edges!

Edit:
I just reread the webpage, 'For a 2400 X 600 T + G board we recommend 8 fixings per board'

 

[bluebaron]

Yep but I’m assuming that refers to loose sheets not T&G which will in effect when glued forms a large sheet. Hence only requiring fixing at the edges.

 

[RandomGrinch]

I suspect that a 4 X 6 m board 18mm thick would probably be quite flexible and could suffer from uplift!
And as the manufacturer recommends 8 fixings for a T&G board, I would be happy to go with that.
But they would say that wouldn't they

 

[^woody^]

You don't need them

 

[RandomGrinch]

You don't need them

Go with the boss!

 

[catlad]

There for fixing your insulation down and helping to minimise thermal bridging.

 

[bluebaron]

You don't need them

Thanks woody, can I assume I don’t need anything then?

 

[bluebaron]

sent them back, ill screw some 150mm screws through the lot instead, (yes I know slight thermal bridge).

18mm OSB3/VCL/150mm PIR/18mm OSB3//Edpm