Cold Deck Flat Roof Specification

Consider geography budget and use for the roof to determine the best option.

Cold deck flat roof specification.

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 roof construction. Inverted warm deck roof. Cold deck construction using 160mm between joists and 50mm under of jablite board or 180mm celotex ga3000.

Flat roofs are divided into two main categories due to the position of the insulation in relation to the other elements of construction. When building a flat roof it is vital that a degree of falls is built into the construction to ensure rainwater run off. Usually flat roof constructions are defined as either cold or warm depending on how the thermal insulation is positioned in the construction. Cold roofs have the waterproof layer placed directly onto the roof deck and the insulation inside the roof just above the ceiling.

Cold deck the thickness of insulation required will vary depending on the material you decide to use and the manufacturer s specification. General when constructing flat roofs please consider the following. This is known as a cold roof because the roof deck and roof space are close to the external air temperature. The cold deck roof as shown above has the insulation at ceiling level and.

This is placed over the roof joists and a board normally external ply is laid on top. Ventilated roof void. Thickness varies according to the manufacturer s specifications. The insulation is placed below the waterproof covering and is either mechanically fixed or bitumen bonded on to the top of the deck.

If insulation is installed below the flat roof deck this is called a cold roof. The 18mm roof grade deck is then fixed on top of the rafters leaving suitable air flow between the insulation and the deck. A note to consider before construction. In bs 6229 a roof is defined as flat if it has an overall pitch of 10 degrees or less.

Cold roofs and warm roofs. The two variations of flat roof. There are two types of flat roof. Others would treat even steeper pitches as flat roofs.

In this case ventilation is required and the roof can still become wet with condensation which may cause materials to decay. 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. 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. How are flat roofs defined.

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. From there the flat roof system you choose will determine the materials you apply. The sandwich warm deck roof is the most common type of flat roof.