The tables below show the suggested u values in england wales and.
Sloping roof insulation regulations.
Lightweight insulating concrete lwic.
In order to satisfactorily fulfil this function over a period of years it must be strong stable and durable.
In addition roofs must provide good thermal insulation and prevent the spread of fire from adjacent or adjoining properties.
How to insulate a roof.
Building regulations for insulating a roof heat rises and therefore the building regulations requirements for heat loss through roofs are more stringent than those for walls.
Resist the spread of fire from one property to another.
Scotland or wales type of building domestic or non domestic and the application floor wall or roof.
For an extension will be required to.
Sheet insulation fitted between the rafters the thicker the better but the size of rafter may limit the thickness possible once an allowance has been made for the required 50mm 2 inch air gap.
The function of a roof is to protect the building below from the weather.
Warm deck this is where the insulation is placed on top of the rafters joists and the roof covering is then placed over the insulation.
A qualified roofing contractor will be able to advise on this but here are some of the main guidelines.
Cold deck this is where the insulation is placed between the joists rafters or in between the ceiling joists in the case of a pitch roof.
Dual purpose structural deck and insulating planks.
A new roof e g.
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.
The insulated plasterboard should then be placed with the long edges running across the rafters.
Be able to support loads weights provide resistance to heat loss insulation be ventilated to protect from condensation in most cases have adequate drainage.
New roofs weight loading advertisement.
The limiting u value the maximise u value which cannot be exceeded required under current building regulations for the roof is 0 20w m.
Ventilated roofs require a 50 mm air gap above the insulation timber stop battens can be nailed into the side of the rafters to give the correct air gap when installing the insulation.
Pitched roofs overview.
No ventilation is required for these types of roofs.
The insulation used in low slope roof assemblies typically falls into one of the four categories.
Sprayed polyurethane foam spf.
According to the uk building regulations pitched roofs should achieve the u value of 0 18 w m2 depending on.