Cracks in wall / subsidance. trees Not that far from property

[skhudy]

Hi, I've noticed some cracks in a double story extension built some time ago, I'm reliably told by the pervious owner who was the niece of a builder, who owned, built the extension and lived in the property previously - 40 years between them.

I did put it down to some settling of the building but think its more than that, as rooms refurbed 5 years ago which had cracks is showing cracks again (from ground floor up to 1st)

Started looking online and realised the obvious cause - there are a couple of fairly tall trees (40-50ft tall at a guess?) coming up to I'd guess 40 years old, 7 and 10 meters away respectively. I'm not sure what species - possibly birch. Ironically I have through about the trees because a detatched garage is now just few inches from one of them.

The obvious course of action is to have the trees removed asap. Once removed, aside from remediation to the cracks, is there any other thing that may have to be considered?

I was thinking if the trees stop sucking up the water any further movement should be abated

Thanks

 

[KenGMac]

skhudy, good evening.

Several things?

Are there any external cracks, and if they exist, do they mimic the internal cracking? [I have assumed that the cracking you describe are indeed internal??]

Be very, very careful as far as tree removal goes, a lot of trees are "protected" and as such [the last time I had anything to do with them] there was a very, very, hefty fine for doing anything at all to some trees, as I recall a fine of £ 20,000 can be imposed.

As for the cracks, how wide are they? and any chance of a few images??

Ken.

 

[Notch7]

I'm not sure what species - possibly birch

According to NHBC, birch is low water demand.

http://nhbccampaigns.co.uk/landingpages/techzone/previous_versions/2011/Part4/section2/appendix.htm

foundation movement happens when you have high water demand trees or hedges in the zone of influence and soils with high shrinkage potential.

Removing trees to mitigate ground shrinkage has to be done carefully- generally the advice is to do it over 3 seasons. Do it in one go and there's a risk of ground heave.

You need to find out what soil you have and what the tree species are.

Interestingly I know somebody that used to water the ground near part of his house as he claimed in dry weather it stopped subsidence.....it prob wouldn't stop it, but I've no idea!

 

[^woody^]

Once removed, aside from remediation to the cracks, is there any other thing that may have to be considered

Ground heave.
Or
Trees are just one potential cause of cracking.
Or
Internet self diagnosis may be wrong

 

[skhudy]

Ok I've returned, and the trees in question are Ash. there are actually 3 of them, about 60ft high, but not a wide canopy, 2 at 7m away, 1 at 9meters away. none of the trees are protected as a different one was taken down a couple of years ago and the council sent maps showed nothing in the vacinity.

The soil is heavy clay when you dig down a meter.

Its a cavity wall, the external brickwork shows minor cracks along the pointing on the 2nd floor up mirroring the internal cracks which are in the ground and upper room. The Internal leaf is concrete blocks, and the cracks were 5mm or so when the room was plastered 5 years ago with bonding, the new cracking in the plaster are a couple of mm, mirroring where they were before.

that NHBC link is great! one to file away.

In all, the trees I hadn't paid much notice to are huge, towering well above the building. definitively going to get them seen to. They will eventually cause a lot of headaches as they mature. they are self seeded, not in an Arial picture left to us showing cars from the 80s and just on our side of the boundary - they can potentially damage to the neighbors whos house is just as close.

 

[lostinthelight]

Did you need to declare the close proximity of the trees for your house insurance, the question has been asked on every Ive had.