Safe Distance of Trees from Houses & Buildings

Safe Distance of Trees Around Typical Farmhouse (Image by David Mark from Pixabay)
Safe Distance of Trees Around Typical Farmhouse (Image by David Mark from Pixabay)

The Safe Distance of Trees from Houses & Buildings concerns this time the "Kalliergeia" editorial team. Which team, responding to a number of requests from only one reader, cites interesting (for the team) facts about this issue.

And first of all, reference is made to the root system of trees, where the basic functions and role of the roots are described in brief, without omitting, however, the dispelling of some myths regarding the area they occupy on the ground.

Then the issue of the soil type emerges, and in fact a specific one, where mainly in cases of wrong approaches, small or large damages from the action of the root system of the trees in houses and buildings are expected.

Then the direct and indirect damages caused are typologically recorded.

The following are general recommendations for the prerequisites that the interested professional or hobbyist, as well as anyone else in any case intending to plant trees around structures and buildings, should keep in mind.

Empirical determination of tree planting distances is then discussed, and the wonderful (to us) presentation concludes by a list of trees with their respective safe planting distances.

The area occupied by the root system of trees in the horizontal direction exceeds the diameter of its canopy.

Distance of Trees from Houses - Tree Root System Extent
Tree Root System Extent
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Formation and Extent of the Root System of Trees

In trees, roots perform two main functions roles:

  • They support them
  • They supply them with water and mineral nutrients from the soil

To meet the demands of these roles they are formed and extended accordingly.

In terms of formation, lateral woody roots grow from the primary root and bear a more or less dense network of non-woody roots.

Growth of woody roots in the soil is largely radial and horizontal and does not reflect the type of branching exhibited by branches in tree canopy.

In relation to the area occupied by the root system, it is generally observed that it exceeds – in the horizontal direction – both the projection of the diameter of the tree’s canopy (often 2 or even 3 times) and its height.

And while the growth in depth varies, it is a fact that the main absorptive area of the roots is located up to 50 to 60 cm from the soil surface.

The development of the root system – as long as there are no obstacles – corresponds to the needs of the tree. And the volume and area it occupies is connected:

  • With the composition and structure of the soil
  • The availability of water and nutrients
  • Soil temperature and oxygen availability

Safe Distance of Trees from Houses & Buildings

Distance of Trees from Houses - Crack in Brickwork Due to Soil Subsidence
Crack in Brickwork Due to Soil Subsidence

Soil and Damage from Tree Roots

To determine the safe distance of trees from houses, buildings, but also from their foundations, it is necessary to take into account the soil type.

And this is because it has been observed that the majority of damage from tree roots occurs in the so-called expansive or shrinkable soils. Where expansive are those soils whose composition includes clay minerals, while their characteristic feature is great plasticity.

Expansive soils exhibit small or large volumetric changes related to variation in moisture content. When there is a lack of moisture the soils shrink, while after rewetting their volume increases.

In the first case and during periods of drought, the roots of the trees, in their attempt to continue supplying water to the plants, contribute to the further shrinkage of these soils.

A consequence of the phenomenon of shrinkage (as well as expansion) is the appearance of damage to buildings and constructions, from cracks and subsidence of the soil.

Safe Distance of Trees from Houses & Buildings

Tree Root Damage to Asphalt
Tree Root Damage to Asphalt

Distinguishing Damage to Structures and Infrastructure Caused by Trees

Damage to structures and infrastructure from trees and their roots is varied. Most of the time they are not serious, but that doesn’t mean they don’t cost money. But the few times that the damages are really serious, then they don’t just cost but their consequences can be extremely dangerous to man.

In general, it could be said that damages are divided into two types, direct and indirect. These two types of damage are mentioned immediately below.

Direct Damages

Direct damage can be caused by both the roots and the trunks (trunk flares) and branches of trees, and includes but is not limited to:

  • The destruction of underground and above-ground structures and materials of utility networks
  • The destruction of the infrastructure of parks and public or private gardens
  • The displacement, lifting or distorting of dividing and retaining walls, walls of houses and buildings, path slabs, stepping stones, pavements, etc.

Indirect Damages

Indirect damage is caused by tree roots in expansive soils, by the process previously described. Here, however, it is worth pointing out that in addition to the shrinkage of these soils caused by living trees, damage can also be caused by cutting them. The soil may then swell from the excess water – with all that implies for houses, buildings and structures.

Safe Distance of Trees from Houses & Buildings

Brickwork Crack From Tree Or Sometimes Can Judge a Book By Its Cover
Brickwork Crack From Tree Or Sometimes Can Judge a Book By Its Cover

General Recommendations before New Tree Planting

To avoid unpleasant surprises during the growth periods of new tree plantings in gardens and surrounding environment of buildings, some basic recommendations follow.

  • Before planting, the dimensions that the tree acquires when it reaches the stage of full maturityshould have been taken into account. This ensures that – among other things – adequate space is provided for the normal development of the root system, without causing damage to nearby buildings and constructions.
  • Tree choices should be limited to those species whose root system responds positively to the hard landscape materials and the way of construction of paths, atriums, patios and drivewayswhen they are to be planted next to or near them.
  • Particular care needs to be taken when selecting tree species to be planted in expansive (swelling) soils with regard to their water requirements. The wrong choice can contributeto the occurrence of subsidence phenomena in houses and buildings.
  • When tree plantings are to follow in newly constructed buildings, which will be carried out especially in expansivesoils, the contribution of a specialist arborist or landscape architect during the planning and study stage for the foundations of the buildings is considered essential.

Safe Distance of Trees from Houses & Buildings

Distance of Trees from Houses - Severe Damage to House from Roots & Tree Trunk
Severe Damage to House from Roots & Tree Trunk

Determination of Safe Tree Planting Distances from Buildings

For the immediate determination of safe distances from houses and buildings, at which it is recommended to plant the new trees, there is an empirical, but usefully successful rule.

According to this rule, the selection of the planting location of a tree is made at half the length of the diameter of the canopy.

The canopy diameter is taken as the tree’s full maturity, while the safe distance is measured vertically to the base of the building or structure.

Safe Distance of Trees from Houses & Buildings

Alphabetical List of Trees (A-Z)

Immediately below is an indicative Alphabetical list of trees with the safety distances from buildings and structures. The presentation follows the format:

Tree Botanical Name (Common Name) Height x Diameter – in m [Distances – in m]

Note

In the distance fields, where there are two numbers, the smaller one specifies the tree planting position from the corner of a building – a distance which is calculated in all cases at 45°.

Index

A

Acer campestre (Field Maple) 12 x 8 [6-8]

Acer capillipes (Red Snake Bark Maple) 10 x 6 [5]

Acer cappadocicum (Cappadocian Maple) 15 x 8 [6]

Acer davidii (Pere David’s Maple) 10 x 7 [5]

Acer ginnala (Amur Maple) 6 x 4 [4]

Acer griseum (Paper-bark Maple) 8 x 6 [5-6]

Acer hersii (Hers’ Maple) 10 x 7 [5]

Acer negundo (Box Elder) 10 x 8 [6]

Acer palmatum (Japanese Maple) 5 x 4 [2-4]

Acer platanoides (Norway Maple) 18 x 10 [7-8]

Acer pseudoplatanus (Sycamore) 20 x 12 [10]

Acer rubrum (Red Maple) 18 x 10 [7-8]

Acer rufinerve (Grey-budded Snake Bark Maple) 10 x 7 [5]

Acer saccharinum (Silver Maple) 18 x 10 [7-8]

Aesculus x carnea “Briottii” (Red Horse Chestnut) 14 x 10 [7]

Aesculus hippocastanum (Horse Chestnut) 18 x 12 [10]

Alnus glutinosa (Common Alder) 16 x 8 [6]

Alnus cordata (Italian Alder) 16 x 8 [6]

Alnus incana (Grey Alder) 16 x 8 [6]

Amelanchier laevis (Snowy Mespilus) 6 x 4 [3-5]

Araucaria araucana (Monkey Puzzle) 16 x 5 [5-6]

B

Betula pubescens “Pendula” (Silver Birch) 18 x 10 [6]

Betula jacquemontii (Whitebarked Himalayan Birch) 15 x 10 [5-6]

Betula utilis (Himalayan Birch) 14 x 8 [4]

C

Carpinus betulus (Hornbeam) 14 x 8 [7-8]

Carpinus betulus “Fastigiata” (Fastigiate Hornbeam) 14 x 8 [5-6]

Castanea sativa (Sweet Chestnut) 18 x 12 [10-12]

Cedrus atlantica (Atlas Cedar) 18 x 12 [10-12]

Cedrus deodara (Deodar) 18 x 12 [10-12]

Chamaecyparis lawsoniana “Ellwoodii” (Lawson Cypress) 8 x 3 [4-5]

Chamaecyparis lawsoniana “Fletcheri” (Lawson Cypress) 8 x 3 [4-5]

Cotoneaster frigidus (Tree Cotoneaster) 5 x 4 [3-4]

Crataegus crus-galli (Cockspur Thorn) 6 x 4 [3-4]

Crataegus lavallei (Hybrid Cockspur Thorn) 6 x 4 [3-4]

Crataegus “Paul’s Scarlet” (Red Hawthorn) 12 x 5 [4-5]

Crataegus x prunifolia (Broad-leaved Cockspur Thorn) 5 x 5 [3-4]

X Cupressocyparis leylandii (Leyland Cypress) 20 x 5 [7-10]

Cupressus glabra (Smooth Arizona Cypress) 12 x 12 [8-10]

Cupressus macrocarpa (Monterey Cypress) 20 x 10 [8-10]

D

Davidia involucrata (Dove Tree) 12 x 8 [6-7]

E

Eucalyptus niphophila (Snow Gum) 6 x 4 [4]

F

Fagus sylvatica (Beech) 25 x 20 [12-14]

Fraxinus excelsior (Ash) 25 x 16 [12-14]

Fraxinus excelsior “Pendula” (Weeping Ash) 8 x 10 [7-8]

Fraxinus oxycarpa “Raywood” (Raywood Ash) 20 x 14 [12-14]

Fraxinus ornus (Manna Ash) 10 x 6 [5-6]

G

Ginkgo biloba (Maidenhair Tree) 16 x 6 [6-8]

I

Ilex x altaclerensis (Highclere Holly) 10 x 6 [4-6]

Ilex aquifolium (Common Holly) 10 x 6 [4-6]

J

Juglans regia (Walnut) 18 x 12 [10]

L

Laburnum x waterii (Voss‘s Laburnum) 8 x 4 [4-5]

Larix decidua (Common Larch) 16 x 6 [5-6]

Liriodendron tulipifera (Tulip Tree) 16 x 10 [8-10]

M

Malus floribunda (Japanese Crab) 5 x 6 [4-5]

Malus hupehensis (Hupei Crab) 6 x 6 [4-5]

Malus “John Downie” (Crab) 7 x 5 [4-5]

Malus tschonoskii “Pillar” (Apple) 10 x 5 [5-6]

Metasequoia glyptostroboides (Dawn Redwood) 18 x 6 [8]

Morus nigra (Black Mulberry) 5 x 5 [3-4]

N

Nothofagus oblique (Roble Beech) 18 x 12 [10]

P

Pinus cembra (Stone Pine) 16 x 6 [5-6]

Pinus nigra (Austrian Pine) 20 x 8 [6-8]

Pinus nigra var. maritima (Corsican Pine) [6-8]

Pinus parviflora (Japanese White Pine) 8 x 6 [5-6]

Pinus sylvestris (Scots Pine) 16 x 6 [5-6]

Picea omorika (Serbian Spruce) 20 x 3 [6-10]

Platanus x hispanica (London Plane) 18 x 12 [10-12]

Pyrus calleryana “Chanticleer” (Ornamental Pear) 12 x 6 [4-6]

Populus alba (White Poplar) 18 x 14 [8-10]

Populus nigra subsp. betulifolia (Native Black Poplar) 18 x 14 [10]

Populus nigra Italica (Lombardy Poplar) 20 x 4 [8-12]

Populus x canadensis “Serotina” (Black Italian Poplar) 20 x 18 [10-14]

Populus tremula (Aspen) 14 x 8 [8]

Prunus avium (Wild Cherry) 16 x 12 [10]

Prunus cerasifera (Myrobalan Plum) 6 x 4 [3-5]

Prunus pissardii (Purple/leaved Plum) 6 x 4 [3-5]

Prunus dulcis (Almond) 6 x 5 [3-5]

Prunus x hillieri “Spire” (Ornamental Cherry) 8 x 3 [3-5]

Prunus lusitanica (Portugese Laurel) 5 x 5 [3-5]

Prunus sargentii (Sargent’s Cherry) 8 x 6 [5]

Prunus padus (Bird Cherry) 10 x 6 [5-6]

Prunus serrulata “Amanogawa” (Japanese Cherry) 10 x 2 [4]

Prunus serrulata “Hokusai” (Japanese Cherry) 6 x 5 [4-5]

Prunus serrulata “Kanzan” (Japanese Cherry) 10 x 8 [6]

Prunus serrulata “Pink Perfection” (Japanese Cherry) 6 x 5 [4-5]

Prunus serrulata “Shirofugen” (Japanese Cherry) 6 x 6 [4-5]

Prunus serrulata “Shirotae” (Japanese Cherry) 8 x 8 [6]

Prunus serrulata “Tai-Haku” (Japanese Cherry) 10 x 8 [6]

Prunus serrulata “Ukon” (Japanese Cherry) 8 x 6 [6]

Prunus subhirtella (Spring Cherry) 8 x 5 [5]

Prunus subhirtella “Autumnalis” (Autumn Cherry) 8 x 5 [5]

Prunus x yedoensis (Yoshino Cherry) 10 x 8 [6]

Pyrus salicifolia (Weeping Pear) 6 x 4 [3-4]

Q

Quercus rubra (Red Oak) 20 x 12 [8-10]

Quercus cerris (Turkey Oak) 20 x 12 [8-10]

Quercus coccinea (Scarlet Oak) 20 x 10 [8-10]

Quercus ilex (Holm Oak) 16 x 10 [8-10]

Quercus petraea (Sessile Oak) 20 x 10 [8-10]

Quercus robur (English Oak) 20 x 16 [12]

R

Robinia pseudoacacia (False Acacia) 18 x 10 [7-10]

S

Salix alba (White Willow) 25 x 16 [10-14]

Salix caprea (Goat Willow) 14 x 6 [6-7]

Salix fragilis (Crack Willow) 18 x 14 [7-12]

Salix x sepulcralis “Chrysocoma” (Golden Weeping Willow) 18 x 20 [12-14]

Sorbus aria (Whitebeam) 10 x 6 [4-8]

Sorbus aucuparia (Rowan) 18 x 6 [4-6]

Sorbus “Embley” (Chinese Scarlet Rowan) 8 x 6 [4-6]

Sorbus hupehensis (Hupeh Rowan) 8 x 6 [4-6]

Sorbus x intermedia (Swedish Whitebeam) 8 x 6 [4-6]

Sorbus sargentiana (Sargent’s Rowan) 8 x 6 [4-6]

Sorbus x churingiaca (Bastard Service Tree) 10 x 5 [4-6]

T

Taxus baccata (Yew) 10 x 8 [6]

Tilia cordata (Small-leaved Lime) 20 x 10 [10]

Tilia x euchlora (Caucasian Lime) 16 x 8 [7-8]

Tilia x europaea (Common Lime) 30 x 16 [10-12]

Tilia platyphyllos (Large-leaved Lime) 25 x 16 [10-12]

Tsuga canadensis (Eastern Hemlock) 20 x 10 [10]

U

Ulmus glabra (Wych Elm) 18 x 10 [8-10]

Ulmus procera (English Elm) 20 x 10 [10-12]

Ulmus minor "Sarniensis" (Wheatley Elm) 18 x 8 [6-8]

References

The References to this safe distance article entitled Safe Distance of Trees from Houses & Buildings are presented by The Doors with their wonderful in its timelessness song Waiting For The Sun.

… Or Waiting for Godot.

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