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Last Updated: Thursday, 19 May, 2005, 00:42 GMT 01:42 UK
Subsidence warning over new trees
Oak tree
People often underestimate how large trees can grow, experts say
Homeowners have been advised to take greater care over planting trees or risk potential subsidence problems.

More than one in 10 have planted trees close to their house, according to a survey by insurance firm Zurich.

Many people have also chosen tree types such as willows, oaks or elms that tend to cause more damage, the study showed.

A Forestry Commission spokesman said people's lack of knowledge about the space and soil type needed by different tree species could add to the problem.

Subsidence is generally caused by changes underground which cause foundations to shift. Cracks in the walls are often the first clue.

'Lost connection'

Trees close to houses can pose a threat because they take water from the soil and can exacerbate any shrinkage caused by hot weather.

Dr Mark Render, of the Forestry Commission, said subsidence was a greater potential problem in areas of clay soil, such as the Thames Valley and Vale of York.

He advised homeowners to consult experts before choosing a tree - particularly if they have only a small garden.

Pick the right size tree for your garden
Find out your soil type
Be aware Edwardian and Victorian houses often have shallow foundations
Ask an expert before cutting down a tree - the soil may shift later because of extra moisture

"I think there's a responsibility for garden centres to make sure they are selling the right trees to the right people to put in the right places," he said.

"The vast majority of urban dwellers now really have no connection with rural matters and therefore they have no idea of how big trees will grow."

Anyone concerned about a tree already growing near their home can contact the Aboricultural Association for local advice, Dr Render added.

The charity Trees for Cities, which encourages the planting of trees in urban areas, says people should be aware that some older houses have only shallow foundations.

'No panic'

"People need to think about the size of a tree. Anything that's going to get very big is going to have a very big root system," said chief executive Graham Simmonds.

"What we don't want is for people to panic and stop planting trees, so if a house has good foundations and you plant at a sensible distance, it should be OK."

Willow tree
Small ornamentals are better near homes than willow, elm and poplar

Of the 1,500 people questioned for Zurich's survey, one in 10 said they knew someone who had paid out more than 30,000 to repair damage caused by subsidence.

Less than a third had ordered a full structural survey of a property they were buying and only 10% raised questions about trees, the poll showed.

Subsidence is not a growing problem but people's awareness of it is increasing, said Andrew Buckley, of the Royal and Sun Alliance insurance firm.

The hot, dry summer of 2003 led to a large rise in the number of claims, he said.

Experts warn climate change could bring more such weather, making prevention of tree-related subsidence even more important.

Runners to raise cash for trees
28 Apr 05 |  London
Council 'plans 4,500 tree cull'
27 Feb 05 |  London
Subsidence heat warning
13 Aug 03 |  Business
DNA finds root of the problem
28 Aug 02 |  England

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