Below from the dwelling and has not less than three quarters of its roof area and one half its exposed wall area made from.
Flat roof extension building regs.
To comply with part l of the building regulations 2010 all roofs to rooms except those in unheated buildings should be thermally insulated to a maximum u value of of 0 18 w m k.
Heat rises and therefore the building regulations requirements for heat loss through roofs are more stringent than those for walls.
Flat roof this usually consists of felting which has a slight fall to allow rain water to drain off.
To comply with part l of the building regulations flat roofs must achieve u values of 0 18 w m k or lower.
A roof is defined in bs 6229 as a flat roof if it has a pitch of 10 degrees or less.
The limiting u value the maximise u value which cannot be exceeded required under current building regulations for the roof is 0 20w m.
This is placed over the roof joists and an board normally external ply is laid on top.
A qualified roofing contractor will be able to advise on this but here are some of the main guidelines.
There must be a slope of 1 80.
The steels or rsj s rolled steel joists are often built into one or both walls to give added stability to the roof structure.
Insulating flat roof extensions.
Traditionally flat roofs were constructed with cold decks where the spaces between the joists were packed with mineral wool type insulation placed above the ceiling like a conventional loft.
A flat roof must be strong durable and stable throughout its lifetime.
Flat roof 0 18 extensions to form conservatories the accepted definition of conservatory for building control purposes in hertfordshire is a ground level extension that is thermally separated see a.
It must provide adequate protection against the elements keeping the buildings structure and interior dry.
Flat roof warm deck the type of insulation for this is usually of a rigid type and the thickness will vary depending on the manufacturer s specifications.
A lower u value indicates better insulation properties hence u value requirements usually specify a maximum value.
Thickness varies according to the manufacturer s specifications.
Building regulations for insulating a roof.
This usually consists of felting which has a slight fall to allow rain water to drain off to enable compliance with the requirements of the building regulations to be demonstrated full details of the new roof will be needed including materials and their dimensions and performance properties.
Part h of the building regulations regarding drainage state that water should drain to one or two edges.
When installing or repairing a flat roof you must adhere to building regulations.
