Fitting brand new Epdm on a warm flat roof

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Hi

Brand new on here as a member, but have got loads of useful info off other threads :)

I'm putting a brand new roof on my extension
I.E.
Joists, 18mm OSB3, V.B, 100mm Insulation, 9mm WPB ply
Fascia boards on the sides

The extra height isnt a problem as i'm using 400mm fascia boards

The thing that i cant get my head around and bothering me is

Do i butt the 100mm insulation up against the exterior fascia boards or do i need to use a 100mm high casing around the insulation before i put the side fascia's on??

Thanks for any advise anyone can give

ZZ
 
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Hi

Brand new on here as a member, but have got loads of useful info off other threads :)

I'm putting a brand new roof on my extension
I.E.
Joists, 18mm OSB3, V.B, 100mm Insulation, 9mm WPB ply
Fascia boards on the sides

The extra height isnt a problem as i'm using 400mm fascia boards

The thing that i cant get my head around and bothering me is

Do i butt the 100mm insulation up against the exterior fascia boards or do i need to use a 100mm high casing around the insulation before i put the side fascia's on??

Thanks for any advise anyone can give

ZZ

span the celotex over the joists and then lay the OSB 3 over that. Get tongue and groove deck sheets. 9mm wbp is too flimsy. It'll look nasty when you screw it down. PU foam between your foil faced celotex and foil tape the joints so you maintain a good vapour control layer.

Regarding the fascias. You can encase the insulation with OSB or literally nail the fascias to the joists and over sail up past the insulation. If you do this make sure you use full replacement fascia.

Remember to cut celotex in between the joists around the perimeter of the roof.
 
span the celotex over the joists and then lay the OSB 3 over that. Get tongue and groove deck sheets. 9mm wbp is too flimsy. It'll look nasty when you screw it down. PU foam between your foil faced celotex and foil tape the joints so you maintain a good vapour control layer.

Regarding the fascias. You can encase the insulation with OSB or literally nail the fascias to the joists and over sail up past the insulation. If you do this make sure you use full replacement fascia.

Remember to cut celotex in between the joists around the perimeter of the roof.

Im using 18mm osb3 on top of the joists then putting the celotex on top of the osb3 then putting 12mm NOT 9mm wpb ply on top of the celotex its going to be like a sandwich LoL

How thick does the fascia board need to be cos iv got 2 lengths at 5mtrs free
The size is 9mm wide x 400mm Height

Could i just put 2 boards together to make 18mm

Thanks
 
span the celotex over the joists and then lay the OSB 3 over that. Get tongue and groove deck sheets. 9mm wbp is too flimsy. It'll look nasty when you screw it down. PU foam between your foil faced celotex and foil tape the joints so you maintain a good vapour control layer.

Regarding the fascias. You can encase the insulation with OSB or literally nail the fascias to the joists and over sail up past the insulation. If you do this make sure you use full replacement fascia.

Remember to cut celotex in between the joists around the perimeter of the roof.

Im using 18mm osb3 on top of the joists then putting the celotex on top of the osb3 then putting 12mm NOT 9mm wpb ply on top of the celotex its going to be like a sandwich LoL

How thick does the fascia board need to be cos iv got 2 lengths at 5mtrs free
The size is 9mm wide x 400mm Height

Could i just put 2 boards together to make 18mm

Thanks

Kingspan and Celotex both do a boarded Insulation, which EPDM can be applied directly to that btw.

But securing the 12mm OSB3 to the Insulation is always a good idea, as its not so flimsy.
 
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Apologies for jumping in but thought I would post in here rather than start a new topic about the same thing. I'm having a warm deck on a new extension- drawings have specified the celotex td126 which has a 6mm ply facing that the epdm can be adhered to - it doesn't sound particularly substantial to me only having 6mm- should I put an 18mm deck on top? And should there be a deck underneath the celotex or should it go straight onto the joists?

Or would it be cheaper to just build 2 decks to sandwich normal celotex boards rather than the td126?

Thanks in advance.
 
Apologies for jumping in but thought I would post in here rather than start a new topic about the same thing. I'm having a warm deck on a new extension- drawings have specified the celotex td126 which has a 6mm ply facing that the epdm can be adhered to - it doesn't sound particularly substantial to me only having 6mm- should I put an 18mm deck on top? And should there be a deck underneath the celotex or should it go straight onto the joists?

Or would it be cheaper to just build 2 decks to sandwich normal celotex boards rather than the td126?

Thanks in advance.

No, 18mm OSB should not go on top, this is what your main decking should be on top of the joists.

So;

Joists, then 18mm OSB3, then Kingspan, then your ply substrate on top whether it be the 6mm board on the kingspan or overboard it with 9 or 12mm OSB 3/2. Then its ready for EPDM.
 
Apologies for jumping in but thought I would post in here rather than start a new topic about the same thing. I'm having a warm deck on a new extension- drawings have specified the celotex td126 which has a 6mm ply facing that the epdm can be adhered to - it doesn't sound particularly substantial to me only having 6mm- should I put an 18mm deck on top? And should there be a deck underneath the celotex or should it go straight onto the joists?

Or would it be cheaper to just build 2 decks to sandwich normal celotex boards rather than the td126?

Thanks in advance.

No, 18mm OSB should not go on top, this is what your main decking should be on top of the joists.

So;

Joists, then 18mm OSB3, then Kingspan, then your ply substrate on top whether it be the 6mm board on the kingspan or overboard it with 9 or 12mm OSB 3/2. Then its ready for EPDM.

Thanks for the quick reply. So would it be cheaper to just use 'normal' insulation and overboard it rather than the td126 that comes ready made as such?
 

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