SCOTTISH EXECUTIVE

Building Regulations: Technical Standards

Appendix E: Tables for the determination of the thicknesses of insulation required to achieve given U-values

CONTENTS OF APPENDIX E

TABLES

Table E1 Base thickness of insulation between ceiling joists or rafters
Table E2 Base thickness of insulation between and over joists or rafters
Table E3 Base thickness for continuous insulation
Table E4 Allowable reductions in thickness for common roof components

Walls

Table E5 Base thickness of insulation layer
Table E6 Allowable reductions in base thickness for common components
Table E7 Allowable reductions in base thickness for concrete components
Table E8 Allowable reductions in base thickness for timber frame walls

Ground floors

Table E9 Insulation thickness for solid floors in contact with the ground
Table E10 Insulation thickness for suspended timber ground floors
Table E11 Insulation thickness for suspended concrete beam and block ground floors

Upper floors

Table E12 Exposed and semi-exposed upper floors of timber construction
Table E13 Exposed and semi-exposed upper floors of concrete construction
Table E14 Exposed and semi-exposed upper floors - allowable reductions in base thickness for common components

Building materials

Table E15 Thermal conductivity of some common construction materials

Notes:

1. The values in these tables have been derived using the proportional area method, taking into account the effects of thermal bridging where appropriate.
2. Intermediate values can be obtained from the tables by linear interpolation.
3. As an alternative to using these tables, the procedures in Appendices A and F can be used to obtain a more accurate calculation of the amount of insulation required.

EXAMPLE CALCULATIONS

Roofs

Example 1 Pitched roof with insulation between ceiling joists or between rafters
Example 2 Pitched roof with insulation between and over ceiling joists
Example 3 Industrial roof with outer sheeting
Example 4 Concrete deck roof

Walls

Example 5 Masonry cavity wall with internal insulation
Example 6 Masonry cavity wall filled with insulation
Example 7 Masonry wall with partial cavity-fill
Example 8 Semi-exposed solid wall
Example 9 Timber-frame wall

Ground floors

Example 10 Solid floor in contact with the ground
Example 11 Suspended timber floor

ROOFS

Table E1 to Part J Appendix E: Base thickness of insulation between ceiling joists or rafters

	Thermal conductivity of insulant (W/mK)
Design U-value (W/m²K)		0.02	0.025	0.03	0.035	0.04	0.045	0.05
Design U-value (W/m²K)		Base thickness of insulating material (mm)
	A	B	C	D	E	F	G	H
1	0.20	167	209	251	293	335	376	418
2	0.25	114	142	170	199	227	256	284
3	0.30	86	107	129	150	171	193	214
4	0.35	69	86	103	120	137	154	172
5	0.40	57	71	86	100	114	128	143
6	0.45	49	61	73	85	97	110	122

Table E2 to Part J Appendix E: Base thickness of insulation between and over joists or rafters

	Thermal conductivity of insulant (W/mK)
Design U-value (W/m²K)		0.02	0.025	0.03	0.035	0.04	0.045	0.05
Design U-value (W/m²K)		Base thickness of insulating material (mm)
	A	B	C	D	E	F	G	H
1	0.20	126	145	166	187	209	232	254
2	0.25	106	120	136	152	169	187	204
3	0.30	86	104	116	129	143	157	171
4	0.35	69	86	102	112	124	135	147
5	0.40	57	71	86	100	109	119	129
6	0.45	49	61	73	85	97	107	115

Note:

Tables E1 and E2 are derived for roofs with the proportion of timber at 8%, corresponding to 48 mm wide timbers at 600 mm centres, excluding noggings. For other proportions of timber the U-value can be calculated using the procedure in Appendix A.

Table E3 to Part J Appendix E: Base thickness for continuous insulation

	Thermal conductivity of insulant (W/mK)
Design U-value (W/m²K)		0.02	0.025	0.03	0.035	0.04	0.045	0.05
Design U-value (W/m²K)		Base thickness of insulating material (mm)
	A	B	C	D	E	F	G	H
1	0.20	97	122	146	170	194	219	243
2	0.25	77	97	116	135	154	174	193
3	0.30	64	80	96	112	128	144	160
4	0.35	54	68	82	95	109	122	136
5	0.40	47	59	71	83	94	106	118
6	0.45	42	52	62	73	83	94	104

Table E4 to Part J Appendix E: Allowable reductions in thickness for common roof components

		Thermal conductivity of insulant (W/mK)
		0.02	0.025	0.03	0.035	0.04	0.045	0.05
Concrete slab density (Kg/m³)		Reduction in base thickness of insulating material (mm) for each 100 mm of concrete slab
	A	B	C	D	E	F	G	H
1	600	11	13	16	18	21	24	26
2	800	9	11	13	15	17	20	22
3	1100	6	7	9	10	12	13	15
4	1300	5	6	7	8	9	10	11
5	1700	3	3	4	5	5	6	7
6	2100	2	2	2	3	3	4	4
Other materials and components		Reduction in base thickness of insulating material (mm)
7	10 mm plasterboard	1	2	2	2	3	3	3
8	13 mm plasterboard	2	2	2	3	3	4	4
9	13 mm sarking board	2	2	3	3	4	4	5
10	12 mm Calcium Silicate liner board	1	2	2	2	3	3	4
11	Roof space (pitched)	4	5	5	6	7	8	9
12	Roof space (flat)	3	4	5	6	6	7	8
13	19 mm roof tiles	0	1	1	1	1	1	1
14	19 mm asphalt (or 3 layers of felt)	1	1	1	1	2	2	2
15	50mm screed	2	3	4	4	5	5	6

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