Flat Roof Insulation Requirements Uk

U value of a flat roof to comply with part l of the building regulations 2010 all roofs to rooms except those in unheated buildings should be thermally insulated to a maximum u value of of 0 18 w m k.

Flat roof insulation requirements uk.

Warm deck the type of insulation for this is usually of a rigid type and the thickness will vary depending on the manufacturer s specifications. In most cases there will not be a loft in a building that features flat roofing. The typical u value of an existing uninsulated flat roof is 1 5w m2k. This means that your approach to insulation will differ from a standard pitched roof.

There are two basic categories of roof design. Ventilation is required for these roofs. The target should be to achieve a u value of 0 25w m2k or better. Cold deck this is where the insulation is placed between the joists rafters or in between the ceiling joists in the case of a pitch roof.

To achieve this add 100 to 160mm of insulation above the structural deck dependant upon insulant conductivity. A u value of 0 55 w m k is used for cavity insulation and 0 30 w m k for internal or external wall insulation. A cold roof has the insulation placed below the structural deck which thus remains cold. This is best done when the roof covering needs replacing anyway.

With a flat roof this issue does not arise but the u value constraint and the amount of insulation needed is just the same. The waterproof layer is above the insulation and a vapour control layer is placed below the insulation. Room in the roof insulation. Our guides to building regulations in england adl1a 2013 building regulations.

Find out more. Achieving a u value of 0 20w m meaning your roof will be better insulated than your walls will need 120mm thickness of rigid foam or 200mm of mineral wool or natural insulation. If you are replacing more than 25 of the roofing area then you will also need to replace the thermal insulation. Depending on where you live in the uk snowfall must also sometimes be considered in determining the gradient of the fall.

A lower u value indicates better insulation properties hence u value requirements usually specify a maximum value. A warm roof has the insulation above the structural deck which is thus kept warm. Laying flat roof insulation as a rule any roof with a pitch below 10 is classified as a flat roof. England new dwellings.

Summary of flat roof building regulations.