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  • EPDM Flat Roofing Systems for the Trade & DIY
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Warm Deck Flat Roof Systems

Warm Deck Roof Designs for EPDM

The warm deck roof design is the modern construction method for flat roof systems and is preferred wherever this option is possible.

Solid (closed cell) roof insulation such as Kingspan or Celotex is placed on top of the roof deck rather than in between the rafters. A vapour barrier needs to be installed to reduce condensation in the roof structure. The insulation and vapour barrier can be mechanically fixed using fasteners and washers or a self-adhesive vapour barrier such as Alutrix can be installed with insulation bonded on top, using PU Adhesive Battens. This removes the need for mechanical fasteners that can cause cold bridging.


The Mechanically Fixed Warm Deck Can Be Installed As Follows:

Roof Deck - Minimum 18mm ply or OSB3 deck.

New vapour barrier or existing felt membrane left in-situ

Kingspan TR26 foil backed insulation, or similar

Overboard the insulation with a 9mm / 11mm ply or OSB3 board

Screw the 9mm board and insulation down into the existing roof joists

Install EPDM rubber roof as per installation instructions

Warm Deck Roof Design with Visqueen Polythene Vapour Barrier and Mechanically Fixed Insulation


The Self Adhesive Vapour Barrier for Warm Deck Can Be Installed As Follows:

Roof Deck - Minimum 18mm ply or OSB3. (OSB (Oriented Strand Board)

Alutrix Self Adhesive Vapour Barrier Bonded with FG35 Primer

Inst-Stik PU Adhesive Glue Battens

Kingspan TR27 tissue faced insulation or similar

Install EPDM rubber roof as per installation instructions.

N.B. The Self Adhesive Vapour barrier offers significant advantages over screw fixing as it enables the roof to be made watertight prior to the EPDM rubber membrane being installed


Warm Deck Roof Design with Self Adhesive Alutrix Vapour Barrier & Insta-Stik Insulation Adhesive

Building Regulations

Please consult Part "L" building regulations as the information printed above may have been superseded. We have attached a link here from London Flat Roofing explaining a little more about your obligations as a roofer and home owner under Part L Building Regulations in relation to flat roofing:

Building Regulations Part L Explained ref: Flat Roofs

ALUTRIX 600 Self Adhesive Vapour Barrier

ALUTRIX 600 Self Adhesive Vapour Barrier

From Square Metre
INSTA-STIK Roofing Adhesive 750ml

INSTA-STIK Roofing Adhesive 750ml

From Square Metre