The Building Regulations
The 
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Before you carry out any structural work, or construct a new extension or loft conversion, you must first ensure it complies with the Building Regs.
Typical examples of works requiring consent are:-
Alterations to drainage, strengthening roof structures, removal of chimney breasts, fitting roof windows, and demolishing or making new openings in walls.
Some works can be 'self-certified' by registered installers such as replacement windows and even electrical installations.
The Building Regulations are grouped into ’approved documents' (A to Q) according to subject.
Architects and Chartered Surveyors base their designs around these requirements. The normal procedure is to produce drawings
( typically 1:50 or 1:100 scale) of the proposed works and submit them to your local council Building Control Department, where they will be checked for compliance.
For larger projects you may be asked to obtain structural engineer’s calculations, so the Council can be sure the loads are adequately supported.
some typical Local Authority BC guidance notes
How to make An Application: Useful advice from Wigan Council B.Control
Summary of U-value Requirements
U-values for extending homes
|
Element |
2010 Part L |
|
WALLS |
0.28 W/m2k |
|
FLOORS |
0.22 |
|
FLAT ROOFS |
0.18 |
|
PITCHED ROOFS - insulated at rafter level ( e.g. sloping ceilings - 'warm roofs' ) - insulated at ceiling level ( e.g. normal loft insulation - 'cold roofs' )
|
0.18 0.16 |
|
DOORS |
1.8 |
WINDOWS & rooflights |
1.6 or WER Band C |
U-values for renovating buildings
|
Element |
Threshold |
2010 Part L |
|
|
|
|
|
Floor |
0.35 |
0.25 |
|
Wall |
0.70 |
0.30 |
|
Pitched roof |
0.35 |
0.18 |
|
Flat roof |
0.35 |
0.18 |
|
|
|
|
Renovation of thermal elements
Replacing the covering on a flat roof now triggers the requirement to upgrade insulation ( to 0.18)
The ‘trigger values’ are now 50% of area of the element being renovated (was 25%) or 25% of the total building envelope.
e.g. if removing plaster from a bedroom wall, the relevant area = the external wall in the room – not the area of the whole main wall.
Download BUILDING REGS DOCUMENTS here
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