Cold Roof Insulation Thickness

A cold flat roof is one where the insulation is between or between and below the roof joists.

Cold roof insulation thickness.

A cold roof has the insulation placed below the structural deck which thus remains cold. With a flat roof this issue does not arise but the u value constraint and the amount of insulation needed is just the same. It allows insulation to be added without having to replace the waterproofing on. The roof covering is then laid over the ply.

The insulation is below the deck but above the plasterboard. The quest for greater energy efficiency in buildings has led to increasing interest and need for insulation improvements in hvac equipment more airtight construction new materials and assemblies. It should be of the maximum available thickness. The recommended depth of blanket style insulation glass or mineral wool for a loft is 250 to 270 mm.

Cold deck the thickness of insulation required will vary depending on the material you decide to use and the manufacturer s specification. If you already have insulation but it was put in some time ago it is worth checking the. Between and under joists. A ventilation gap usually 50mm should be.

Find your zone on the map and then use the chart to determine the level of insulation you need to properly insulate your attic walls floors and crawlspaces. This construction relies on a vapour control layer working effectively and in tandem with a continuous ventilated airspace to disperse the water vapour to atmosphere before it reaches the cold deck and condenses. Flat roof insulation thickness the chosen insulation laid on top of this should be able to take the weight of anything put above it on the roof without compression or protected from compression by further sheeting. 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.

A cold deck flat roof will typically require insulation to be installed between the roof joists to comply with building regulation requirements. The typical u value of an existing uninsulated flat roof is 1 5w m2k. A ventilation gap usually 50mm should be provided between the top of the insulation and underside of the roof covering to allow the air to flow across. This is used for refurbishment e g.

Unless the joists are exceptionally deep there is also likely to be a requirement to install insulation to the underside of the joists as the upper 50mm of joist space is usually required to be left clear for ventilation purposes. Refurbishing an existing timber joisted flat roof which has no insulation.