4.2 Building near trees

Appendix 4.2-A

Water demand and mature height of trees

Table 12

Broad leafed trees
Water demand	Species		Mature height [m]
High	Elm
		English	24
		Wheatley	22
		Wych	18
	Eucalyptus		18
	Hawthorn		10
	Oak
		English	20
		Holm	16
		Red	24
		Turkey	24
	Poplar
		Hybrid black	28
		Lombardy	25
		White	15
	Willow
		Crack	24
		Weeping	16
		White	24
Moderate	Acacia false		18
	Alder		18
	Apple		10
	Ash		23
	Bay Laurel		10
	Beech		20
	Blackthorn		8
	Cherry
		Japanese	9
		Laurel	8
		Orchard	12
		Wild	17
	Chestnut
		Horse	20
		Sweet	24
	Lime		22
	Maple
		Japanese	8
		Norway	18
	Mountain Ash		11
	Pear		12
	Plane		26
	Plum		10
	Sycamore		22
	Tree of Heaven		20
	Walnut		18
	Whitebeam		12
Low	Birch		14
	Elder		10
	Fig		8
	Hazel		8
	Holly		12
	Honey Locust		14
	Hornbeam		17
	Laburnum		12
	Magnolia		9
	Mulberry		9
	Tulip tree		20

Coniferous trees
Water demand	Species		Mature height [m]
High	Cypress
		Lawson's	18
		Leyland	20
		Monterey	20
Moderate	Cedar		20
	Douglas fir		20
	Larch		20
	Monkey Puzzle		18
	Pine		20
	Spruce		18
	Wellingtonia		30
	Yew		12

Note:

Appendix 4.2-B

Foundation Depth Charts

Table 13 Determination of D/H Value

Distance D (m)	Tree height H (m)
	2	4	6	8	10	12	14	16	18	20	22	24	26	28	30
1	0.50	0.25	0.17	0.13	0.10	0.08	0.07	0.06	0.06	0.05	0.05	0.04	0.04	0.04	0.03
2	1.00	0.50	0.33	0.25	0.20	0.17	0.14	0.13	0.11	0.10	0.09	0.08	0.08	0.07	0.07
3		0.75	0.50	0.38	0.30	0.25	0.21	0.19	0.17	0.15	0.14	0.13	0.12	0.11	0.10
4		1.00	0.67	0.50	0.40	0.33	0.29	0.25	0.22	0.20	0.18	0.17	0.15	0.14	0.13
5			0.83	0.63	0.50	0.42	0.36	0.31	0.28	0.25	0.23	0.21	0.19	0.18	0.17
6			1.00	0.75	0.60	0.50	0.43	0.38	0.33	0.30	0.27	0.25	0.23	0.21	0.20
7			1.17	0.88	0.70	0.58	0.50	0.44	0.39	0.35	0.32	0.29	0.27	0.25	0.23
8				1.00	0.80	0.67	0.57	0.50	0.44	0.40	0.36	0.33	0.31	0.29	0.27
9				1.13	0.90	0.75	0.64	0.56	0.50	0.45	0.41	0.38	0.35	0.32	0.30
10					1.00	0.83	0.71	0.63	0.56	0.50	0.45	0.42	0.38	0.36	0.33
11					1.10	0.92	0.79	0.69	0.61	0.55	0.50	0.46	0.42	0.39	0.37
12					1.20	1.00	0.86	0.75	0.67	0.60	0.55	0.50	0.46	0.43	0.40
13						1.08	0.93	0.81	0.72	0.65	0.59	0.54	0.50	0.46	0.43
14						1.17	1.00	0.88	0.78	0.70	0.64	0.58	0.54	0.50	0.47
15							1.07	0.94	0.83	0.75	0.68	0.63	0.58	0.54	0.50
16							1.14	1.00	0.89	0.80	0.73	0.67	0.62	0.57	0.53
17							1.21	1.06	0.94	0.85	0.77	0.71	0.65	0.61	0.57
18								1.13	1.00	0.90	0.82	0.75	0.69	0.64	0.60
19								1.19	1.06	0.95	0.86	0.79	0.73	0.68	0.63
20									1.11	1.00	0.91	0.83	0.77	0.71	0.67
21									1.17	1.05	0.95	0.88	0.81	0.75	0.70
22										1.10	1.00	0.92	0.85	0.79	0.73
23										1.15	1.05	1.96	0.88	0.82	0.77
24										1.20	1.09	1.00	0.92	0.86	0.80
25											1.14	1.04	0.96	0.89	0.83
26											1.18	1.08	1.00	0.93	0.87
27												1.13	1.04	0.96	0.90
28												1.17	1.08	1.00	0.93
29		Where no value is given in the table, minimum foundation depths apply (i.e. 1.0m, 0.9m and 0.75m for high, medium and low volume change potential soils respectively).										1.21	1.12	1.04	0.97
30													1.15	1.07	1.00
31													1.19	1.11	1.03
32														1.14	1.07
33														1.18	1.10
34														1.21	1.13
35															1.17
36															1.20

Chart 1 Soils with HIGH volume change potential: Modified Plasticity Index 40% or greater

(see Design clause D5(b))

Chart 2 Soils with MEDIUM volume change potential: Modified Plasticity Index between 20% and less than 40%

(see Design clause D5(b))

Chart 3 Soils with LOW volume change potential: Modified Plasticity Index 10 to less than 20%

(see Design clause D5(b))

Appendix 4.2-C

Foundation depth tables

Table 14 - HIGH shrinkage soil and HIGH water demand tree 

Broad leafed trees

Foundation depth (m)
Distance D (m)	Tree height H (m)
	8	10	12	14	16	18	20	22	24	26	28	30
1
2
3				Foundations greater than 2.5m deep to be Engineer designed
4	2.50
5	2.25	2.50
6	2.00	2.30	2.50
7	1.75	2.10	2.35	2.50
8	1.50	1.90	2.20	2.40	2.50
9	1.25	1.70	2.00	2.25	2.40	2.50
10	1.00	1.50	1.85	2.10	2.25	2.40	2.50
11	1.00	1.30	1.70	1.95	2.15	2.30	2.40	2.50
12	1.00	1.10	1.50	1.80	2.00	2.20	2.30	2.45	2.50
13		1.00	1.35	1.65	1.90	2.10	2.20	2.35	2.45	2.50
14		1.00	1.20	1.50	1.75	1.95	2.10	2.25	2.35	2.45	2.50
15			1.00	1.40	1.65	1.85	2.00	2.15	2.25	2.35	2.45	2.50
16			1.00	1.25	1.50	1.75	1.90	2.05	2.20	2.30	2.40	2.45
17			1.00	1.10	1.40	1.65	1.80	1.95	2.10	2.20	2.30	2.40
18				1.00	1.25	1.50	1.70	1.90	2.00	2.15	2.25	2.30
19				1.00	1.15	1.40	1.60	1.80	1.95	2.05	2.15	2.25
20					1.00	1.30	1.50	1.70	1.85	2.00	2.10	2.20
21					1.00	1.20	1.40	1.60	1.75	1.90	2.00	2.10
22					1.00	1.10	1.30	1.50	1.70	1.85	1.95	2.05
23						1.00	1.20	1.45	1.60	1.75	1.90	2.00
24						1.00	1.10	1.35	1.50	1.65	1.80	1.90
25							1.00	1.25	1.45	1.60	1.75	1.85
26							1.00	1.15	1.35	1.50	1.65	1.80
27							1.00	1.05	1.25	1.45	1.60	1.70
28								1.00	1.20	1.35	1.50	1.65
29								1.00	1.10	1.30	1.45	1.60
30									1.00	1.20	1.40	1.50
31									1.00	1.15	1.30	1.45
32									1.00	1.05	1.25	1.40
33										1.00	1.15	1.30
34										1.00	1.10	1.25
35											1.00	1.20
36											1.00	1.10
37		1.0m minimum foundation depth									1.00	1.05
38												1.00

Coniferous trees

Foundation depth (m)
Distance D (m)	Tree height H (m)
	8	10	12	14	16	18	20	22	24	26	28	30
1						Foundations greater than 2.5m deep to be Engineer designed
2	2.50
3	1.95	2.25	2.50
4	1.45	1.85	2.15	2.35	2.50
5	1.00	1.45	1.80	2.05	2.20	2.35	2.50
6		1.00	1.45	1.75	1.95	2.15	2.25	2.40	2.50
7		1.00	1.10	1.45	1.70	1.90	2.05	2.20	2.30	2.40	2.50
8			1.00	1.15	1.45	1.65	1.85	2.00	2.15	2.25	2.35	2.40
9				1.00	1.20	1.45	1.65	1.80	1.95	2.10	2.20	2.25
10					1.00	1.20	1.45	1.65	1.80	1.90	2.05	2.15
11						1.00	1.25	1.45	1.60	1.75	1.90	2.00
12							1.00	1.25	1.45	1.60	1.75	1.85
13							1.00	1.05	1.25	1.45	1.60	1.70
14								1.00	1.10	1.30	1.45	1.60
15									1.00	1.10	1.30	1.45
16										1.00	1.15	1.30
17											1.00	1.15
18												1.00
19				1.0m minimum foundation depth
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38

Table 15 - HIGH Shrinkage soil and MODERATE water demand tree

Broad leafed trees

Foundation depth (m)
Distance D (m)	Tree height H (m)
	8	10	12	14	16	18	20	22	24	26	28	30
1	2.20	2.25	2.25	2.30	2.30	2.30	2.35	2.35	2.35	2.35	2.35	2.35
2	1.95	2.05	2.10	2.15	2.20	2.20	2.25	2.25	2.25	2.30	2.30	2.30
3	1.70	1.85	1.95	2.00	2.05	2.10	2.15	2.15	2.20	2.20	2.20	2.25
4	1.50	1.65	1.80	1.90	1.95	2.00	2.05	2.10	2.10	2.15	2.15	2.15
5	1.25	1.50	1.65	1.75	1.85	1.90	1.95	2.00	2.05	2.05	2.10	2.10
6	1.00	1.30	1.50	1.60	1.70	1.80	1.85	1.90	1.95	2.00	2.00	2.05
7	1.00	1.10	1.35	1.50	1.60	1.70	1.75	1.85	1.90	1.90	1.95	2.00
8		1.00	1.20	1.35	1.50	1.60	1.65	1.75	1.80	1.85	1.90	1.90
9			1.00	1.20	1.35	1.50	1.60	1.65	1.70	1.75	1.80	1.85
10			1.00	1.10	1.25	1.40	1.50	1.55	1.65	1.70	1.75	1.80
11				1.00	1.15	1.30	1.40	1.50	1.55	1.65	1.70	1.75
12					1.00	1.20	1.30	1.40	1.50	1.55	1.60	1.65
13					1.00	1.05	1.20	1.30	1.40	1.50	1.55	1.60
14						1.00	1.10	1.25	1.35	1.40	1.50	1.55
15							1.00	1.15	1.25	1.35	1.40	1.50
16							1.00	1.05	1.20	1.25	1.35	1.40
17								1.00	1.10	1.20	1.30	1.35
18									1.00	1.15	1.20	1.30
19									1.00	1.05	1.15	1.25
20										1.00	1.10	1.20
21		1.0m minimum foundation depth									1.00	1.10
22											1.00	1.05
23												1.00

Coniferous trees

Foundation depth (m)
Distance D (m)	Tree height H (m)
	8	10	12	14	16	18	20	22	24	26	28	30
1	1.90	2.00	2.10	2.15	2.15	2.20	2.20	2.25	2.25	2.25	2.30	2.30
2	1.40	1.60	1.75	1.85	1.90	2.00	2.00	2.05	2.10	2.10	2.15	2.15
3	1.00	1.20	1.40	1.55	1.65	1.75	1.80	1.85	1.90	1.95	2.00	2.00
4		1.00	1.10	1.30	1.40	1.55	1.60	1.70	1.75	1.80	1.85	1.90
5			1.00	1.00	1.15	1.30	1.40	1.50	1.60	1.65	1.70	1.75
6					1.00	1.10	1.20	1.35	1.40	1.50	1.55	1.60
7						1.00	1.00	1.15	1.25	1.35	1.40	1.50
8								1.00	1.10	1.20	1.30	1.35
9									1.00	1.05	1.15	1.20
10										1.00	1.00	1.10
11												1.00
12
13
14
15
16
17
18
19
20
21		1.0m minimum foundation depth
22
23

Table 16 - HIGH shrinkage soil and LOW water demand tree

Broad leafed trees

Foundation depth (m)
Distance D (m)	Tree height H (m)
	8	10	12	14	16	18	20	22	24	26	28	30
1	1.60	1.65	1.70	1.70	1.70	1.75	1.75	1.75	1.75	1.75	1.75	1.75
2	1.40	1.50	1.55	1.60	1.60	1.65	1.65	1.65	1.65	1.70	1.70	1.70
3	1.20	1.35	1.40	1.50	1.50	1.55	1.60	1.60	1.60	1.65	1.65	1.65
4	1.00	1.20	1.30	1.35	1.40	1.45	1.50	1.55	1.55	1.55	1.60	1.60
5		1.00	1.15	1.25	1.30	1.40	1.40	1.45	1.50	1.50	1.55	1.55
6			1.00	1.15	1.20	1.30	1.35	1.40	1.40	1.45	1.50	1.50
7				1.00	1.10	1.20	1.25	1.30	1.35	1.40	1.40	1.45
8					1.00	1.10	1.20	1.25	1.30	1.35	1.35	1.40
9						1.00	1.10	1.15	1.20	1.25	1.30	1.35
10							1.00	1.10	1.15	1.20	1.25	1.30
11								1.00	1.10	1.15	1.20	1.25
12		1.0m minimum foundation depth							1.00	1.10	1.15	1.20
13										1.00	1.10	1.15
14											1.00	1.05
15												1.00

Table 17 - MEDIUM shrinkage soil and HIGH water demand tree

Broad leafed trees

Foundation depth (m)
Distance D (m)	Tree Height H (m)
	8	10	12	14	16	18	20	22	24	26	28	30
1
2						Foundations greater than 2.5m deep to be Engineer designed
3	2.40	2.50
4	2.20	2.35	2.45
5	1.95	2.20	2.30	2.40	2.50
6	1.75	2.00	2.20	2.30	2.40	2.45	2.50
7	1.55	1.85	2.05	2.20	2.30	2.35	2.45	2.50
8	1.35	1.70	1.90	2.05	2.20	2.25	2.35	2.40	2.45	2.50
9	1.15	1.50	1.75	1.95	2.10	2.20	2.25	2.35	2.40	2.45	2.50	2.50
10	0.90	1.35	1.60	1.80	1.95	2.10	2.20	2.25	2.30	2.35	2.40	2.45
11	0.90	1.15	1.50	1.70	1.85	2.00	2.10	2.20	2.25	2.30	2.35	2.40
12	0.90	1.00	1.35	1.60	1.75	1.90	2.00	2.10	2.20	2.25	2.30	2.35
13		0.90	1.20	1.45	1.65	1.80	1.95	2.05	2.10	2.20	2.25	2.30
14		0.90	1.05	1.35	1.55	1.70	1.85	1.95	2.05	2.10	2.20	2.25
15			0.90	1.20	1.45	1.60	1.75	1.85	1.95	2.05	2.10	2.20
16			0.90	1.10	1.35	1.55	1.70	1.80	1.90	2.00	2.05	2.10
17			0.90	1.00	1.25	1.45	1.60	1.70	1.85	1.90	2.00	2.05
18				0.90	1.15	1.35	1.50	1.65	1.75	1.85	1.95	2.00
19				0.90	1.05	1.25	1.40	1.55	1.70	1.80	1.90	1.95
20					0.90	1.15	1.35	1.50	1.60	1.75	1.80	1.90
21					0.90	1.05	1.25	1.40	1.55	1.65	1.75	1.85
22					0.90	0.95	1.15	1.35	1.50	1.60	1.70	1.80
23						0.90	1.10	1.25	1.40	1.55	1.65	1.75
24						0.90	1.00	1.20	1.35	1.45	1.60	1.70
25							0.90	1.10	1.25	1.40	1.50	1.60
26							0.90	1.05	1.20	1.35	1.45	1.55
27							0.90	0.95	1.15	1.30	1.40	1.50
28								0.90	1.05	1.20	1.35	1.45
29								0.90	1.00	1.15	1.30	1.40
30									0.90	1.10	1.20	1.35
31									0.90	1.00	1.15	1.30
32									0.90	0.95	1.10	1.25
33										0.90	1.05	1.15
34										0.90	1.00	1.10
35											0.90	1.05
36		0.9m minimum foundation depth									0.90	1.00
37											0.90	0.95
38												0.90

Coniferous trees

Foundation depth (m)
Distance D (m)	Tree Height H (m)
	8	10	12	14	16	18	20	22	24	26	28	30
1								Foundations greater than 2.5m deep to be Engineer designed
2	2.15	2.30	2.45	2.50
3	1.70	1.95	2.15	2.25	2.35	2.45	2.50
4	1.25	1.60	1.85	2.00	2.15	2.25	2.30	2.40	2.45	2.50	2.50
5	0.90	1.25	1.55	1.75	1.95	2.05	2.15	2.20	2.30	2.35	2.40	2.45
6		0.90	1.25	1.50	1.70	1.85	1.95	2.05	2.15	2.20	2.25	2.30
7			1.00	1.25	1.50	1.65	1.80	1.90	2.00	2.10	2.15	2.20
8			0.90	1.00	1.25	1.45	1.60	1.75	1.85	1.95	2.00	2.10
9				0.90	1.05	1.25	1.45	1.60	1.70	1.80	1.90	1.95
10					0.90	1.10	1.25	1.45	1.55	1.65	1.75	1.85
11						0.90	1.10	1.25	1.40	1.55	1.65	1.75
12							0.90	1.10	1.25	1.40	1.50	1.60
13							0.90	0.95	1.10	1.25	1.40	1.50
14								0.90	1.00	1.15	1.25	1.40
15									0.90	1.00	1.15	1.25
16										0.90	1.00	1.15
17											0.90	1.05
18												0.90
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36		0.9m minimum foundation depth
37
38

Table 18 - MEDIUM shrinkage soil and MODERATE water demand tree

Broad leafed trees

Foundation depth (m)
Distance D (m)	Tree height H (m)
	8	10	12	14	16	18	20	22	24	26	28	30
1	1.85	1.85	1.90	1.90	1.95	1.95	1.95	1.95	1.95	1.95	1.95	1.95
2	1.65	1.75	1.80	1.80	1.85	1.85	1.85	1.90	1.90	1.90	1.90	1.90
3	1.45	1.60	1.65	1.70	1.75	1.80	1.80	1.80	1.85	1.85	1.85	1.85
4	1.30	1.45	1.55	1.60	1.65	1.70	1.75	1.75	1.80	1.80	1.80	1.80
5	1.10	1.30	1.40	1.50	1.55	1.60	1.65	1.70	1.70	1.75	1.75	1.80
6	0.90	1.15	1.30	1.40	1.45	1.55	1.60	1.60	1.65	1.70	1.70	1.75
7	0.90	1.00	1.15	1.30	1.40	1.45	1.50	1.55	1.60	1.65	1.65	1.70
8		0.90	1.05	1.20	1.30	1.35	1.45	1.50	1.55	1.55	1.60	1.65
9			0.90	1.10	1.20	1.30	1.35	1.40	1.45	1.50	1.55	1.60
10			0.90	0.95	1.10	1.20	1.30	1.35	1.40	1.45	1.50	1.55
11				0.90	1.00	1.10	1.20	1.30	1.35	1.40	1.45	1.50
12					0.90	1.05	1.15	1.20	1.30	1.35	1.40	1.45
13					0.90	0.95	1.05	1.15	1.25	1.30	1.35	1.40
14						0.90	1.00	1.10	1.15	1.25	1.30	1.35
15							0.90	1.00	1.10	1.15	1.25	1.30
16							0.90	0.95	1.05	1.10	1.20	1.25
17								0.90	1.00	1.10	1.15	1.20
18									0.90	1.00	1.10	1.15
19									0.90	0.95	1.00	1.10
20										0.90	0.95	1.05
21		0.9m minimum foundation depth									0.90	1.00
22											0.90	0.95
23												0.90

Coniferous trees

Foundation depth (m)
Distance D (m)	Tree height H (m)
	8	10	12	14	16	18	20	22	24	26	28	30
1	1.65	1.70	1.75	1.80	1.80	1.85	1.85	1.90	1.90	1.90	1.90	1.90
2	1.25	1.40	1.50	1.55	1.65	1.65	1.70	1.75	1.75	1.80	1.80	1.80
3	0.90	1.10	1.25	1.35	1.45	1.50	1.55	1.60	1.65	1.65	1.70	1.70
4		0.90	0.95	1.10	1.25	1.30	1.40	1.45	1.50	1.55	1.55	1.60
5			0.90	0.90	1.05	1.15	1.25	1.30	1.35	1.40	1.45	1.50
6					0.90	0.95	1.10	1.15	1.25	1.30	1.35	1.40
7						0.90	0.90	1.00	1.10	1.15	1.25	1.30
8								0.90	0.95	1.05	1.10	1.20
9									0.90	0.95	1.00	1.10
10										0.90	0.90	0.95
11												0.90
12
13
14
15
16
17
18
19
20
21		0.9m minimum foundation depth
22
23

Table 19 - MEDIUM shrinkage soil and LOW water demand tree

Broad leafed trees

Foundation depth (m)
Distance D (m)	Tree height H (m)
	8	10	12	14	16	18	20	22	24	26	28	30
1	1.35	1.40	1.40	1.45	1.45	1.45	1.45	1.45	1.45	1.45	1.50	1.50
2	1.20	1.30	1.30	1.35	1.35	1.40	1.40	1.40	1.40	1.45	1.45	1.45
3	1.05	1.15	1.20	1.25	1.30	1.30	1.35	1.35	1.35	1.40	1.40	1.40
4	0.90	1.05	1.10	1.20	1.20	1.25	1.30	1.30	1.30	1.35	1.35	1.35
5		0.90	1.00	1.10	1.15	1.20	1.20	1.25	1.25	1.30	1.30	1.30
6			0.90	1.00	1.05	1.10	1.15	1.20	1.20	1.25	1.25	1.30
7				0.90	1.00	1.05	1.10	1.15	1.15	1.20	1.20	1.25
8					0.90	1.00	1.05	1.10	1.10	1.15	1.20	1.20
9						0.90	1.00	1.05	1.05	1.10	1.15	1.15
10							0.90	0.95	1.00	1.05	1.10	1.10
11								0.90	0.95	1.00	1.05	1.10
12		0.9m minimum foundation depth							0.90	0.95	1.00	1.05
13										0.90	0.95	1.00
14											0.90	0.95
15												0.90

Table 20 - LOW shrinkage soil and HIGH water demand tree

Broad leafed trees

Foundation depth (m)
Distance D (m)	Tree height H (m)
	8	10	12	14	16	18	20	22	24	26	28	30
1	2.35	2.40	2.40	2.40	2.45	2.45	2.45	2.45	2.45	2.45	2.45	2.45
2	2.15	2.25	2.30	2.30	2.35	2.35	2.40	2.40	2.40	2.40	2.40	2.45
3	2.00	2.10	2.15	2.20	2.25	2.30	2.30	2.35	2.35	2.35	2.35	2.40
4	1.80	1.95	2.05	2.10	2.15	2.20	2.25	2.25	2.30	2.30	2.30	2.35
5	1.65	1.80	1.95	2.00	2.10	2.15	2.15	2.20	2.25	2.25	2.25	2.30
6	1.45	1.70	1.80	1.90	2.00	2.05	2.10	2.15	2.15	2.20	2.20	2.25
7	1.30	1.55	1.70	1.80	1.90	2.00	2.05	2.05	2.10	2.15	2.15	2.20
8	1.10	1.40	1.60	1.70	1.80	1.90	1.95	2.00	2.05	2.10	2.10	2.15
9	0.95	1.25	1.45	1.60	1.75	1.80	1.90	1.95	2.00	2.05	2.05	2.10
10	0.75	1.10	1.35	1.50	1.65	1.75	1.80	1.90	1.95	2.00	2.00	2.05
11	0.75	1.00	1.20	1.40	1.55	1.65	1.75	1.80	1.90	1.95	1.95	2.00
12	0.75	0.85	1.10	1.30	1.45	1.60	1.70	1.75	1.80	1.85	1.90	1.95
13		0.75	1.00	1.20	1.40	1.50	1.60	1.70	1.75	1.80	1.85	1.90
14		0.75	0.90	1.10	1.30	1.45	1.55	1.65	1.70	1.75	1.80	1.85
15			0.75	1.00	1.20	1.35	1.45	1.55	1.65	1.70	1.75	1.80
16			0.75	0.90	1.10	1.30	1.40	1.50	1.60	1.65	1.70	1.75
17			0.75	0.80	1.05	1.20	1.35	1.45	1.55	1.60	1.65	1.75
18				0.75	0.95	1.10	1.25	1.35	1.45	1.55	1.60	1.70
19				0.75	0.85	1.05	1.20	1.30	1.40	1.50	1.55	1.65
20					0.75	0.95	1.10	1.25	1.35	1.45	1.50	1.60
21					0.75	0.90	1.05	1.20	1.30	1.40	1.45	1.55
22					0.75	0.80	1.00	1.10	1.25	1.35	1.40	1.50
23						0.75	0.90	1.05	1.20	1.30	1.35	1.45
24						0.75	0.85	1.00	1.10	1.25	1.30	1.40
25							0.75	0.95	1.05	1.15	1.25	1.35
26							0.75	0.85	1.00	1.10	1.20	1.30
27							0.75	0.80	0.95	1.05	1.15	1.25
28								0.75	0.90	1.00	1.10	1.20
29								0.75	0.85	0.95	1.05	1.15
30									0.75	0.90	1.00	1.10
31									0.75	0.85	0.95	1.05
32									0.75	0.80	0.90	1.05
33										0.75	0.85	1.00
34										0.75	0.80	0.95
35											0.75	0.90
36											0.75	0.85
37		0.75m minimum foundation depth									0.75	0.80
38												0.75

Coniferous trees

Foundation depth (m)
Distance D (m)	Tree height H (m)
	8	10	12	14	16	18	20	22	24	26	28	30
1	2.15	2.25	2.30	2.30	2.35	2.35	2.35	2.40	2.40	2.40	2.40	2.40
2	1.80	1.95	2.05	2.10	2.15	2.20	2.25	2.25	2.30	2.30	2.30	2.35
3	1.45	1.65	1.80	1.90	1.95	2.05	2.10	2.10	2.15	2.20	2.20	2.25
4	1.05	1.35	1.55	1.70	1.80	1.85	1.95	2.00	2.05	2.05	2.10	2.15
5	0.75	1.05	1.30	1.50	1.60	1.70	1.80	1.85	1.90	1.95	2.00	2.05
6		0.75	1.05	1.25	1.45	1.55	1.65	1.70	1.80	1.85	1.90	1.95
7		0.75	0.80	1.05	1.25	1.40	1.50	1.60	1.65	1.75	1.80	1.85
8			0.75	0.85	1.05	1.20	1.35	1.45	1.55	1.60	1.70	1.75
9				0.75	0.90	1.05	1.20	1.35	1.45	1.50	1.60	1.65
10					0.75	0.90	1.05	1.20	1.30	1.40	1.50	1.55
11						0.75	0.90	1.05	1.20	1.30	1.35	1.45
12							0.75	0.95	1.05	1.15	1.25	1.35
13							0.75	0.80	0.95	1.05	1.15	1.25
14								0.75	0.80	0.95	1.05	1.15
15									0.75	0.85	0.95	1.05
16										0.75	0.85	0.95
17											0.75	0.85
18												0.75
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37		0.75m minimum foundation depth
38

Table 21 - LOW shrinkage soil and MODERATE water demand tree

Broad leafed trees

Foundation depth (m)
Distance D (m)	Tree height H (m)
	8	10	12	14	16	18	20	22	24	26	28	30
1	1.50	1.50	1.55	1.55	1.55	1.55	1.55	1.55	1.55	1.60	1.60	1.60
2	1.35	1.40	1.45	1.45	1.50	1.50	1.50	1.50	1.55	1.55	1.55	1.55
3	1.20	1.30	1.35	1.40	1.40	1.45	1.45	1.45	1.50	1.50	1.50	1.50
4	1.05	1.15	1.25	1.30	1.35	1.35	1.40	1.40	1.45	1.45	1.45	1.45
5	0.90	1.05	1.15	1.20	1.25	1.30	1.35	1.35	1.40	1.40	1.40	1.45
6	0.75	0.95	1.05	1.15	1.20	1.25	1.30	1.30	1.35	1.35	1.40	1.40
7	0.75	0.85	0.95	1.05	1.10	1.20	1.20	1.25	1.30	1.30	1.35	1.35
8		0.75	0.85	0.95	1.05	1.10	1.15	1.20	1.25	1.25	1.30	1.30
9			0.75	0.90	1.00	1.05	1.10	1.15	1.20	1.25	1.25	1.30
10			0.75	0.80	0.90	1.00	1.05	1.10	1.15	1.20	1.20	1.25
11				0.75	0.85	0.95	1.00	1.05	1.10	1.15	1.15	1.20
12					0.75	0.85	0.95	1.00	1.05	1.10	1.15	1.15
13					0.75	0.80	0.90	0.95	1.00	1.05	1.10	1.15
14						0.75	0.85	0.90	0.95	1.00	1.05	1.10
15							0.75	0.85	0.90	0.95	1.00	1.05
16							0.75	0.80	0.85	0.90	0.95	1.00
17								0.75	0.80	0.90	0.95	1.00
18									0.75	0.85	0.90	0.95
19									0.75	0.80	0.85	0.90
20										0.75	0.80	0.85
21		0.75m minimum foundation depth									0.75	0.85
22											0.75	0.80
23												0.75

Coniferous trees

Foundation depth (m)
Distance D (m)	Tree height H (m)
	8	10	12	14	16	18	20	22	24	26	28	30
1	1.30	1.40	1.40	1.45	1.45	1.50	1.50	1.50	1.50	1.55	1.55	1.55
2	1.00	1.15	1.20	1.25	1.30	1.35	1.40	1.40	1.40	1.45	1.45	1.45
3	0.75	0.90	1.00	1.10	1.15	1.20	1.25	1.30	1.30	1.35	1.35	1.40
4		0.75	0.80	0.95	1.00	1.10	1.15	1.20	1.20	1.25	1.25	1.30
5			0.75	0.75	0.85	0.95	1.00	1.05	1.10	1.15	1.20	1.20
6					0.75	0.80	0.90	0.95	1.00	1.05	1.10	1.15
7						0.75	0.75	0.85	0.90	0.95	1.00	1.05
8								0.75	0.80	0.85	0.95	0.95
9									0.75	0.80	0.85	0.90
10										0.75	0.75	0.80
11												0.75
12
13
14
15
16
17
18
19
20
21		0.75m minimum foundation depth
22
23

Table 22 - LOW shrinkage soil and LOW water demand tree

Broad leafed trees

Foundation depth (m)
Distance D (m)	Tree height H (m)
	8	10	12	14	16	18	20	22	24	26	28	30
1	1.10	1.15	1.15	1.15	1.15	1.15	1.20	1.20	1.20	1.20	1.20	1.20
2	1.00	1.05	1.05	1.10	1.10	1.10	1.15	1.15	1.15	1.15	1.15	1.15
3	0.90	0.95	1.00	1.05	1.05	1.05	1.10	1.10	1.10	1.10	1.10	1.15
4	0.75	0.85	0.90	0.95	1.00	1.00	1.05	1.05	1.05	1.10	1.10	1.10
5		0.75	0.85	0.90	0.95	0.95	1.00	1.00	1.05	1.05	1.05	1.05
6			0.75	0.85	0.90	0.90	0.95	0.95	1.00	1.00	1.05	1.05
7				0.75	0.85	0.85	0.90	0.95	0.95	1.00	1.00	1.00
8					0.75	0.80	0.85	0.90	0.90	0.95	0.95	1.00
9						0.75	0.80	0.85	0.90	0.90	0.95	0.95
10							0.75	0.80	0.85	0.85	0.90	0.90
11								0.75	0.80	0.85	0.85	0.90
12		0.75m minimum foundation depth							0.75	0.80	0.85	0.85
13										0.75	0.80	0.85
14											0.75	0.80
15												0.75

Appendix 4.2-D

Climate zones

Figure 13 Reductions in foundation depth due to climate variations

The foundation depth may be reduced by the amounts shown on the map for each climatic zone (see Design clause D5(e)). Where it is unclear which zone applies, the lower reduction value should be used.

Appendix 4.2-E

Information sources and acknowledgements

INFORMATION SOURCES

Further recommendations and information can be obtained from:

Publications

BS 1377 'Methods of test for soils for civil engineering purposes'

BS 5837 'Guide for trees in relation to construction'

BS 5930 'Code of practice for site investigations'

BRE Digests 240, 241 and 242 'Low rise buildings on shrinkable clay soils', parts 1, 2 and 3

BRE Digest 298 'The influence of trees on house foundations in clay soils'

BRE Digest 412 'Desiccation in clay soils'

Tree Recognition - A Pocket Manual

by Ian Richardson and Rowena Gale, Richardson's Botanical Identifications,
49/51 Whiteknights Road, Reading, Berks RG6 7BB

Field Guide to the Trees of Britain and Northern Europe

by Alan Mitchell, Harper Collins, Glasgow

Geological survey maps

obtainable from British Geological Survey, Nicker Hill, Keyworth, Nottingham NG12 5GG
Tel: 0115 936 3100; www.bgs.ac.uk

Tree root damage to buildings

Vol.1 Causes, Diagnosis and Remedy
Vol. 2 Patterns of Soil Drying in Proximity to Trees on Clay Soils
by P G Biddle, Willowmead Publishing, Wantage OX12 9JA

Organisations

Arboricultural Association

Ampfield House, Ampfield, nr. Romsey, Hants SO51 9PA
Tel: 01794 368717; www.trees.org.uk

Arboricultural Advisory and Information Service

Forest Research Station, Alice Holt Lodge, Wrecclesham, Farnham, Surrey GU10 4LH
Tel: 01420 22022; www.treehelp.info
(Tree Helpline telephone no. 0906 516 1147)

Institution of Civil Engineers

1-7 Great George Street, London SW1P 3AA
Tel: 020 7222 7722; www.ice.org.uk

Institution of Structural Engineers

11 Upper Belgrave Street, London SW1X 8BH
Tel: 020 7235 4535; www.istructe.org.uk

ACKNOWLEDGEMENTS

NHBC gratefully acknowledges the help given by authoritative organisations and individuals in the preparation of this Chapter, particularly:
Building Research Establishment
Dr P G Biddle Arboricultural Consultant

Appendix 4.2-F

Worked example

How to determine foundation depths from the Charts in Appendix 4.2-B or the Tables in Appendix 4.2-C.

Step		Ref	Example
1	Determine the volume change potential of the soil. Ensure the site investigation includes representative sampling and testing.	D5(b)	Site at Oxford, building near a Lombardy Poplar (to be retained) and a Sycamore (to be removed) From laboratory tests, Plasticity Index, Ip = 36%. Test results also report that 100% of particles are smaller than 425µm. Therefore, modified Plasticity Index, From Table 1, Volume change potential = Medium (in the absence of tests assume high volume change potential) This example is typical of Oxford Clay. More than 35% of the particles are smaller than 60µm and therefore the soil is shrinkable. 100% of the particles are smaller than 425µm and therefore the l'p is the same as the lp. A typical Boulder Clay also has more than 35% of particles smaller than 60µm and is therefore also shrinkable. However, it may have only 80% of its particles smaller than 425µm in which case the l'p is 80% of the lp. A typical clayey sand may have less than 30% of its particles smaller than 60µm in which case the soil would be non shrinkable.
2	Establish the species, mature height and water demand of all trees and hedgerows within their influencing radii.	D5(c) and D5(d)	Lombardy Poplar Sycamore From Appendix 4.2-A Mature height = 25m Water demand = High From Appendix 4.2-A Mature height = 22m Water demand = Moderate
3	Plot the trees and hedgerows relative to the foundations and draw their zones of influence to determine which trees will affect the foundation design. Use a scaled plan.	D5(c)
4	Establish the appropriate tree height H to use. Always use the mature height for remaining and proposed trees and hedgerows. The appropriate height to use for removed trees and hedgerows depends on the actual height when they are removed.	D5(d)	Lombardy Poplar Sycamore Tree to remain. Therefore, H  = Mature height   = 25m Tree to be removed Mature height = 22m Actual height = 15m Actual height greater than 50% mature height. Therefore, H  = Mature height   = 22m
5	Measure the distance D from the centre of the trees or hedgerows to the face of the foundation.	D6(c)	Lombardy Poplar Sycamore Distance D = 10m from foundation Distance D = 8m from foundation
6	Select Steps 6C(a) and (b) if using Charts in Appendix 4.2-B to derive depths or select Step 6T if using Tables in Appendix 4.2-C to derive depths. Alternatively the NHBC foundation depth calculator may be used (see Sitework clause S2).
6C (a)	Calculate D/H i.e. distance D from face of foundation (Step 5) divided by the appropriate tree height H (Step 4). Alternatively D/H can be obtained from Table 13 in Appendix 4.2-B.		Lombardy Poplar Sycamore
6C(b)	Determine foundation depth using the Charts in Appendix 4.2-B as follows: Volume change potential Chart number High 1 Medium 2 Low 3		Lombardy Poplar Sycamore In this example the volume change potential is Medium, then from Chart 2 for broadleafed high water demand trees at Foundation depth = 2.33m In this example the volume change potential is Medium, then from Chart 2 for broadleafed moderate water demand trees at Foundation depth = 1.50m The Lombardy Poplar is the tree requiring the greater depth (2.33m)
6T	Determine foundation depth using the Tables in Appendix 4.2-C as follows: Volume change potential Tree water demand Table number High High Moderate Low 14 15 16 Medium High Moderate Low 17 18 19 Low High Moderate Low 20 21 22		Lombardy Poplar Sycamore In this example the volume change potential is Medium and the water demand is High, then from Table 17, for broad leafed high water demand trees at D = 10m and H = 25m, Foundation depth = 2.33m (by interpolation) In this example the volume change potential is Medium and the water demand is Moderate, then from Table 18, for broad leafed moderate water demand trees at D = 8m and H = 22m, Foundation depth = 1.50m The Lombardy Poplar is the tree requiring the greater depth (2.33m)
7	Adjust the depth according to the climatic zone. A reduction may be made for distance north and west of London but the final depth should not be less than the minimum given in each Chart and Table.	D5(e)	Oxford is between 50 and 100 miles NW of London. From Appendix 4.2-D, a reduction of 0.05m is permitted. Final foundation depth = 2.33 - 0.05 = 2.28m
8	Check that the recommendations of this Chapter have been met for: Acceptable foundation types New planting (including shrubs) Non shrinkable soil overlying shrinkable soil Variations in foundation depths Foundations on sloping ground Precautions against heave (including suspended floors) Measurement of foundation depths Foundation trench bottoms Precautions for drainage	D6(a) D6(d), D6(e) D6(f) D6(g), S3(b) D6(h) D8,S4 S3(a) S3(c) S5

 Note:

The above process may be repeated to allow the foundation to be stepped as its distance from the tree increases.