Fruit Trees Subsidence Risk- surely not?
May 8, 2008 by fruitforum
A recent article in the Telegraph newspaper suggested that ‘Families planting fruit trees in pursuit of the “Good Life” are putting their homes at risk of subsidence’. The writer went on to explain that according to figures produced by Sainsbury’s Home Insurance 12% of insurance pay outs for subsidence were caused by trees and that ‘apple or pear topped the list of fruit trees householders intended to plant, followed by cherry and plum trees’.
This seems a little over the top – perhaps Sainsburys are worried about people growing their own fruit! By tradition many are planted against walls, but fruit trees are usually trained and/or on dwarfing rootstocks and their root systems are not so large in these circumstances. Perhaps someone has an answer to this?
Terry Read
To read the Daily Telegraph article go to:
http://www.telegraph.co.uk/news/1900392/%27Planting-fruit-trees-create-subsidence-risk%27.html
The insurance industry is extremely cautious regarding trees and use the maximum known root spread for each variety as the guide to indicate planting distances from properties. Therefore they are referring to aged full size trees. If a neighbour has a tree which is too close to your house there is very little that can be done until after the damage is caused.
Where I have lived for over 40 years we now suffer from hundreds of self sown ash trees so I did a web search for safe distances as many get left to grow in neighbouring gardens. Normally only clay soils which can dry out give any problem as only soil shrinkage can cause damage, as I and my neighbours know only too well after having to claim for three damaged garages each costing over £3000 to rebuild. The trees were leylandii.
The Subsidence Claims Advisory Bureau lists safe distances: for ash trees it is 10 metres, for apple and pear trees 5 metres and for cherry, plum and peach 6 metres. These are obviously very cautious distances. Another web site claims that you can halve the figures. Of course non of this really applies to the modern dwarf rootstocks anyway. As a general rule the root spread should be about equal to the spread of the branches.
The writer of the ‘Telegraph’ article is guilty of sloppy journalism. It looks as though Sainsbury’s insurance arm circulated a ‘research’ note - primarily about general tree-related subsidence risks in clay soil areas - to insurance brokers, several of whom referred to it in varying degrees on their own websites.
The link below seems to be the most complete reference. From it, it is clear that the mention of fruit trees was in a completely different context - merely that of the degree to which house owners were thinking about planting such a tree; nothing to do with the main topic - subsidence - at all.
http://www.easier.com/view/Finance/Insurance/Home/article-176645.html
When you look at the significance of the ‘Daily Telegraph’ article in the real world the connection between building subsidence and fruit trees is vanishingly small.
Firstly, subsidence is only caused by trees drying out soil, and subsequent shrinkage, on clay soils. These only occur in a limited area of the country, mainly in south east England. This is also the area of lowest rainfall.
Secondly, fruit trees are less of a problem than, say, oaks.
Thirdly, most people plant fruit trees on one of the dwarfing rootstocks and the tree is more of a small bush. A wisteria on the wall of the house or a common lilac nearby will take much more moisture out of the soil than an apple.
The amount of moisture a tree or shrub takes out of the soil depends on the leaf area and to some degree on the exposure. Most common shrubs are much leafier than fruit trees.
In my experience insurers, their engineers and arboriculturalists blame trees for subsidence far too often. The cause may be paving round the house removing the rainfall or something else such as when the tree roots can not reach the house due to a retaining wall.