Cold Deck Flat Roof Specification

Cold deck roof construction.

Cold deck flat roof specification.

When building a flat roof it is vital that a degree of falls is built into the construction to ensure rainwater run off. 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. From there the flat roof system you choose will determine the materials you apply. 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.

In bs 6229 a roof is defined as flat if it has an overall pitch of 10 degrees or less. The insulation boards in an inverted warm deck are laid over the structural deck and the waterproof covering. Cold roofs and warm roofs. This is known as a cold roof because the roof deck and roof space are close to the external air temperature.

Cold roofs have the waterproof layer placed directly onto the roof deck and the insulation inside the roof just above the ceiling. The sandwich warm deck roof is the most common type of flat roof. Flat roofs are divided into two main categories due to the position of the insulation in relation to the other elements of construction. In this case ventilation is required and the roof can still become wet with condensation which may cause materials to decay.

The roof covering is then laid over the ply. 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. General when constructing flat roofs please consider the following. The cold deck roof as shown above has the insulation at ceiling level and.

The insulation is placed below the waterproof covering and is either mechanically fixed or bitumen bonded on to the top of the deck. The 18mm roof grade deck is then fixed on top of the rafters leaving suitable air flow between the insulation and the deck. Consider geography budget and use for the roof to determine the best option. Cold deck the thickness of insulation required will vary depending on the material you decide to use and the manufacturer s specification.

Usually flat roof constructions are defined as either cold or warm depending on how the thermal insulation is positioned in the construction. A note to consider before construction. Ventilated roof void. Thickness varies according to the manufacturer s specifications.

Others would treat even steeper pitches as flat roofs. Thickness varies according to the manufacturer s specifications. If insulation is installed below the flat roof deck this is called a cold roof. This is placed over the roof joists and an board normally external ply is laid on top.

The two variations of flat roof. Cold deck construction using 160mm between joists and 50mm under of jablite board or 180mm celotex ga3000. This is placed over the roof joists and a board normally external ply is laid on top. Inverted warm deck roof.