You need sufficient exterior insulation typically.
Exterior flat roof insulation.
With this kind of roof the insulation follows the slope of the roof.
The insulation material is placed between the supporting joists leaving a gap of 50 60mm between the roof and 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.
A roof over a vented unconditioned attic does not need to include any 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.
Many properties use this option as there are no additional costs for scaffolding or organising how to gain safe access to the roof exterior.
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.
Warm flat roof insulation.
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.
However most cathedral ceilings and low slope flat roofs are insulated roof assemblies.
Gable roofs hip roofs intersecting roofs butterfly roofs mansard.
Cold flat roof insulation.
This means there is a vapour control layer in the ceiling and cross ventilation at the eaves or the top of the walls.
Lots of traditional flat roofs are of the cold roof construction type.
Because old roofs were often framed with 2x6s there isn t much room for insulation.
Insulated roof assemblies can be vented or unvented.
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.
Rockwool stone wool roof insulation combines the thermal performance dimensional stability impact resistance and acoustic control required to increase the performance of many flat roof assemblies.
This may help with condensation but causes such a loss of heat that it has been banned in scotland.
And it will be important to maintain the correct ratio of interior to exterior insulation.