Flat Roof Insulation Requirement

Insulation material is placed on top of the roof rather than in between the ceiling and the decking.

Flat roof insulation requirement. For a 1 inch board equivalent of 6 r value. There are two main types of flat roof that require different approaches to installation. Where insulation is mechanically fixed the fixings must be of sufficient length to. If the insulation has a sufficiently high vapour resistance a separate vapour control layer may not be required and the.

Achieving greater r values in attics the higher the r value the better the thermal performance of the insulation. Attic space enclosed rafter or joist space above normally occupied and conditioned interior space assemblies as an economical arrangement of roofing and insulation materials. You can expect to pay about 55 100 sq ft. Insulation requirements for roofs are therefore spread across ibc chapters 12 13 and 15.

Typical recommendations for exterior walls are r 13 to r 23 while r 30 r 38 and r 49 are common for ceilings and attic spaces. There must be a slope of 1 80 part h of the building regulations regarding drainage state that water should drain to one or two edges waterproofing should extend up the adjacent walls at least. Your two best options are spray foam insulation on the underside of the roof sheathing an installation which will require the ceiling to be removed at least partially or the installation of rigid foam on top of the existing sheathing. 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.

The insulation may be fully or partially bonded to the vapour control layer or laid loose. 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. However insulation placement in roof assemblies requires careful review to achieve acceptable hygrothermal performance levels and limit the. Insulation is placed in between the joists underneath the roof surface.

See the department of energy s doe ranges for recommended levels of insulation below. It is top quality and the most cost effective product for your flat roof. With a flat roof this issue does not arise but the u value constraint and the amount of insulation needed is just the same. Continuous insulation zones ashrae 90 1 ashrae 189 1 igcc ibc iecc 2004 2007 2010 2013 2016 2009 2011 2014 2012 2015 2009 2012 2015 0 25 1 15 20 2 15 20 25 3 15 20 25 4 15 20 302535 5 15 20 302535 6 15 20 3035 7 15 20 3540 25 8 20 3540 25 minimum r value non residential above roof deck.

A qualified roofing contractor will be able to advise on this but here are some of the main guidelines. While expensive the best insulation is polyiso rigid foam.