Cold Roof Insulation Thickness

Refurbishing an existing timber joisted flat roof which has no insulation.

Cold roof insulation thickness. A ventilation gap usually 50mm should be. 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. Between and under joists. A cold flat roof is one where the insulation is between or between and below the roof joists.

Cold deck flat roof the thickness of insulation required will vary depending on the material you decide to use and the manufacturer s specification. Cold deck the thickness of insulation required will vary depending on the material you decide to use and the manufacturer s specification. The recommended depth of blanket style insulation glass or mineral wool for a loft is 250 to 270 mm. A cold deck flat roof will typically require insulation to be installed between the roof joists to comply with building regulation requirements.

The roof covering is then laid over the ply. 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. Achieving greater r values in attics the higher the r value the better the thermal performance of the insulation. If you already have insulation but it was put in some time ago it is worth checking the.

It should be of the maximum available thickness. The insulation is below the deck but above the plasterboard. 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. 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.

Senior engineer manager at icynene john broniek makes the case for the unvented attic assembly and why insulating the underside of the roof makes sense. With a flat roof this issue does not arise but the u value constraint and the amount of insulation needed is just the same. 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. 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.

The typical u value of an existing uninsulated flat roof is 1 5w m2k. 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.