Exterior Flat Roof Insulation

The type that is right for your flat roof insulation job depends upon the state of the roof expert opinion on the best type and your budget.

Exterior flat roof insulation.

Lots of traditional flat roofs are of the cold roof construction type. Gable roofs hip roofs intersecting roofs butterfly roofs mansard. With this kind of roof the insulation follows the slope of the roof. Roof types the various types of roofs found on homes sheds garages and other buildings fall into one of the following categories.

This means there is a vapour control layer in the ceiling and cross ventilation at the eaves or the top of the walls. 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. Depending on where you live and the part of your home you re insulating walls crawlspace attic etc you ll need a different r value. It makes a lot of sense if the rafter cavities are already insulated and it is most affordable when the roof needs replacement.

However most cathedral ceilings and low slope flat roofs are insulated roof assemblies. This may help with condensation but causes such a loss of heat that it has been banned in scotland. The insulation material is placed between the supporting joists leaving a gap of 50 60mm between the roof and insulation. A roof over a vented unconditioned attic does not need to include any insulation.

Cold flat roof insulation. Exterior roof insulation retrofit unvented roof covering the roof of an old house with a blanket of insulation makes the house more comfortable and it cuts energy use. Because old roofs were often framed with 2x6s there isn t much room for insulation. You need sufficient exterior insulation typically.

Convenient or not jordan will need exterior insulation over the roof sheathing in order to meet code minimums says ryan lewis advice that is seconded by gba editor martin holladay. Because most flat roofs don t have an attic crawl space or venting the insulation must go underneath the roof s covering on the exterior of the home or be placed on the inside of the home. Adding exterior foam on an old roof is a good idea whenever a reroof is planned it is a once in 50 year opportunity to bring the house up to higher level of energy performance. Insulated roof assemblies can be vented or unvented.

Many properties use this option as there are no additional costs for scaffolding or organising how to gain safe access to the roof exterior.