|
The
New Maximum 'U' Values allowable from April 2002 for dwellings
are detailed below using the Elemental method of Compliance
to Approved Document L1 together with the changes made
in 2007/08.
Maximum
U-values (W/m 2 ) |
Element
Room
in Pitched Roof (New Build)
Room in Pitched Roof (Loft Conversion)
Insulation at floor level only
Flat Roofs
Walls
Floors
Windows/Doors/Rooflights |
2002
0.20
0.30
0.16
0.25
0.35
0.25
2.20/2.00* |
2009
0.16
0.20
0.16
0.16
0.35
0.22
1.80 |
*depending
on timber or metal frame
ROOF,
WALL AND FLOOR INSULATION
Table
1 applies to where Spray Applied Polyurethane
Foam is used for insulation only and includes substrates
such as; Roofing felt, Sarking Timber Boards, Breathable
Membranes, Timber, Concrete, Steel, etc.
Table
1
Roof and Walls |
Floor |
'U'
Value to be achieved (W/m 2 K) |
0.30 |
0.27 |
0.25 |
0.20 |
0.16 |
0.14
|
|
Approximate
Foam depth |
65mm |
75mm |
80mm |
105mm
|
130mm |
150mm |
175mm |
HYBRID
WARM PITCHED ROOFS
Table
2 applies to where Spray Applied Polyurethane
Foam is applied directly to tiles or slates, i.e. with
no roofing felt. The average batten spacing is taken as
150mm centres with 25 x 25mm battens
Table
2
|
Hybrid
Warm Pitched Roof |
'U'
Value to be achieved (W/m 2 K)
|
0.30
|
0.20 |
0.16 |
| Underlined
with plasterboard |
25mm |
25mm |
25mm |
| |
+50mm |
+75mm
|
+120mm |
| With
loft void and 100mm glass |
|
|
25mm |
| Mineral
fibre at ceiling level |
|
|
+
60mm |
HYBRID
WARM FLAT ROOFS
Table
3 assumes 225 x 48mm joists set at 600mm centres under
25 x 38mm counter battens set at 600mm centres,
19mm ply board and semi-permeable pvc weatherproofing
membrane.
Table
3
|
Hybrid
Warm Flat Roof |
'U'
Value to be achieved (W/m 2 K)
|
0.25 |
0.160 |
| With
counter batten |
38mm |
38mm |
| |
+40mm |
+95mm |
| Without
counter battens |
85mm |
155mm
|
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