Consider geography budget and use for the roof to determine the best option.
Cold deck flat roof specification.
The insulation boards in an inverted warm deck are laid over the structural deck and the waterproof covering.
Thickness varies according to the manufacturer s specifications.
Cold deck roof construction.
Cold roofs and warm roofs.
The two variations of flat roof.
The insulation is placed below the waterproof covering and is either mechanically fixed or bitumen bonded on to the top of the deck.
From there the flat roof system you choose will determine the materials you apply.
The roof covering is then laid over the ply.
The 18mm roof grade deck is then fixed on top of the rafters leaving suitable air flow between the insulation and the deck.
The epdm rubber roof membrane is then installed using the contact adhesive onto the deck.
This is placed over the roof joists and an board normally external ply is laid on top.
General when constructing flat roofs please consider the following.
Flat roofs are divided into two main categories due to the position of the insulation in relation to the other elements of construction.
Flat roof u value 0 18 w m2k 2 warm deck flat roof the type of insulation for this is usually of a rigid type and the thickness will vary depending on the manufacturer s specifications.
Inverted warm deck roof.
If insulation is installed below the flat roof deck this is called a cold roof.
How are flat roofs defined.
This is known as a cold roof because the roof deck and roof space are close to the external air temperature.
Usually flat roof constructions are defined as either cold or warm depending on how the thermal insulation is positioned in the construction.
In bs 6229 a roof is defined as flat if it has an overall pitch of 10 degrees or less.
The sandwich warm deck roof is the most common type of flat roof.
Cold deck the thickness of insulation required will vary depending on the material you decide to use and the manufacturer s specification.
Cold roofs have the waterproof layer placed directly onto the roof deck and the insulation inside the roof just above the ceiling.
Thickness varies according to the manufacturer s specifications.
Materials used must be suitable for use in flat roofs roof needs to achieve an external fire rating vapour barriers should be used flat roofs should be.
Cold deck construction using 160mm between joists and 50mm under of jablite board or 180mm celotex ga3000.
There are two types of flat roof.
The definition of a flat roof according to bs 6229 is having a pitch less than 10 o to the horizontal however some in the industry would consider up to 15 o as their definition of a flat roof.
The cold deck roof as shown above has the insulation at ceiling level and.
Ventilated roof void.
In this case ventilation is required and the roof can still become wet with condensation which may cause materials to decay.
This is placed over the roof joists and a board normally external ply is laid on top.
