Warm Deck Roof in flat roof

[firbest]

Hi

I am building a flat roof on my back extension.

I am building a flat roof and above the timber joist i am putting OSB3 board 18mm than with this vapor proof barrier https://www.ebay.co.uk/itm/115612903087 not sure if its the correct item i have bought? If someone can help me that will be great and if its correct do i need to put anything to stick it down?

after the vapor proof barrier i am putting Celotex 150mm PIR insulation (taping the joints together with aluminum foil tape from top and fixed with screw from insulation to OSB 3 bord.

above the insulation i am putting OSB 3 board again and on top of that will be felt.

if someone can help me with the vapor proof barrier as stated above as that where i am thinking i am going wrong.

 

[cdbe]

I used this, with primer from Toolstation (but I think it said on the instructions that you could get away without the primer on clean OSB).

 

[firbest]

thanks for the reply cdbe but the one i purchased is not self adhesive as you have bought maybe i bought the wrong one.

 

[cdbe]

Sorry, didn't realise you'd already bought it.

Aluminium Foil Membrane - Vapour Barrier and Thermal Insulation VCL - 1.5m x 50m (75 SQ/M) - Trade Store Online

Vapour Barrier and Thermal Insulation. Three-layer aluminium foil, a quality option, used in new-build constructions and renovations. Free Next Day UK Delivery.

www.tradestoreonline.co.uk

This gives information suggesting it's suitable l.

 

[phatboy]

If you have a VCL below the insulation, what do you achieve by taping the insulation joints? By that point in the roof, if moisture has got in, you want to let it go.

Also, I'd screw through the top OSB, insulation, bottom deck OSB in one go.

With my flat roof, I just used 1000 gauge plastic sheet