Tree damage to building foundations

[Jo Pedder]

Does any one know anything about this subject, or know of any good references?

I have a wonderful copper birch growing on the border between my garden and my neighbours, who have started making rumblings of concern that the tree could be causing foundation damage. The tree is about 20 foot high (reaches 1st floor windows about mid way) and has probably doubled in height since we bought the house 2 years ago - the previous owner used to cut it back each year, but we wanted to let it gain some height to screen our garden a bit, so most of the height is from thin, new growth.

I think that arborologists use a reference document that allows an approximation of root radius based on crown condition, height and species, but I’ve no idea what it is - it might even be a British Standard.

Also, does anyone know how the tree root system will react if I undertake some severe pruning - if I coppice the tree, will the roots die off / stop growing / grow more to compensate?

If the tree roots do extend up to the building foundations, will their growth be powerful enough to cause damage anyway?

Any thoughts appreciated.

Jo

[BigAl]

There was a very good TV Programmeof a few years back called 'Nature Special - City Trees', which I occasionally show my pupils. I guess it must have been on one of the BBC Channels. In this programme, they showed how trees evewn survive growing through buildings in central London e.g. car parks.

The problem with trees is the transpiration rate, which draws up water from the soil, and can cause proximal buildings to subside. Again, a few years ago, there as a graph published in the property pages of the Daily Mail showing how far trees should be away from property. Some trees are worse than others, e.g. willo spp are among the worst. However, as a rule of thumb (this article said) that a tree should be no closer to a building than its height, if it was laid down on the ground. I can try and look up a few facts and figures if you like?

[BigAl]

The article also says, "But don't rush out and chop down any tree within 20 metres of your house. Besides the environmental damage and breach of tree preservations, you could cause further problems - the extra water left in the groiund by your DIY lumberjacking might cause your house to rise or heave."

" 'If you haven't got a problem now, keep the tree to its present size by sensible pruning and the cyhances are you won't have a problem in the future', says Bob Hooker of the Subsidence Claims Advisory Bureau."

[BigAl]

The D.Mail article was publisheds in1997 and, to give you an idea, at that time the Subsidence Claims Advisory Service would arrange a survey for £125.

There telephone no. was 01424 733727.

[Jo Pedder]

Thanks Al, I don't think that the tree will be doing any damage at the moment - I guess the worry is that it may cause damaage in the future, some heavy pruning may be in order to limit it's growth back to a shrub/hedge

[henrya]

As for foundation damage, it's something that people disagree about. I had problems with clay shrinkage a few years ago, and of one tree, one consultant said "That needs reducing, it's causing terrible problems" whereas the next man said "Oh, it's so far from the house it doesn't make any difference." How can us poor punters make an informed choice?

Birch trees are pretty shallow rooted, I believe, though, as they are prone to dying off in droughts, I guess they may use plenty of water. I have seen several quite close to buildings that don't seem to cause any problems.

henrya

[Jo Pedder]

just to update,

I'm afraid the trees got to go, i've had advice from a arboricultural forum and a council officer has also expressed consern as my neighbour intends to build a conservatory next to it.

Oh, well shame to see it go, but to be honest it's going to be good fun getting it down!

[henrya]

Jo,

Let's get this straight - you are going to have to cut down a tree that might damage the foundations of a conservatory that has yet to be built? Sounds crazy to me!

henrya

[Jo Pedder]

No, the council officer expressed concern for the foundations of our flats as well as the conservatory. The arbor forum experts suggested that the 'safe' distance for a this species is somewhere between 7 and 15 m from a building, depending on what reference material you read, ground substrate etc. My tree is about 3m from the house, which means that it could cause subsidence through drying soil around foundations, causing the soil to shrink, or if it falls in wind cause direct damage to property and further risk to foundations from roots being pulled out.

I'm not concerned to remove the tree on wildlife grounds as it has never had a nest, and I’ve rarely even seen birds perching on it. The soil under the tree is parched and overshaded with no ground flora, and our garden's mice all burrow on the other side of the garden, where there is more vegetation and they can make good use of our bird table (more a mouse table really). Even the hedgehog family that forage in our garden don't take a route under this tree.

[henrya]

Thanks, Jo, for clarifying. Makes a bit more sense now!

henrya