A u value is a measure of heat loss in a building element such as a wall floor or roof.
Roof u value wales.
We provide u value calculations to show compliance with current building regulations standards and best practice.
The required u value will depend on the location of the project england scotland or wales type of building domestic or non domestic and the application floor wall or roof.
It can also be referred to as an overall heat transfer co efficient and measures how well parts of a building transfer heat.
For more information see our articles and how to videos below.
Note the distinction between the domestic and non domestic columns.
The new notional building parameters are published in the document as they are in england however unlike england the tighter mandatory limiting fabric values will limit the variations.
Ridge board this forms the apex of the roof and is where the rafters are fixed to both sides.
This section contains the approved documents l1a and l1b for download below.
The tables below show the suggested u values in england wales and scotland.
Each element enables the roof to span across the building and support the tiles covering on top as well as being able to transfer the loads weight created by any wind and snow down to the walls.
What is a u value.
The easiest way of getting a u value calculation is by using our free online u value calculator.
Where more than 25 per cent of a ceiling below a cold loft space or flat roof is being replaced then building regulations would normally apply.
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Roof 0 15 well i say taken care actually the document states that even these values should only be considered as a starting point towards compliance.
This means that the higher the u value the worse the thermal performance of the building envelope.
A lower u value indicates better insulation properties hence u value requirements usually specify a maximum value.
Determine the thickness of the insulation layer above the joists required to achieve a u value of 0 20 w m2k for the roof construction shown below.
These can be supported with a detailed report.
U value of a flat roof 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.
It is proposed to use mineral wool insulation between and over the joists with a thermal conductivity of 0 04 w m k.
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There are two additional compliance guides for building.
Check out our guide on what performance is required for the uk insulation building regulations.
Listed below are the typical elements of a pitched roof.
