Building near trees (building regs)

[foliedouce]

Does anyone have any experience of building near trees (3 metres away) and what depth of footings where required by building control#?

[V8RX7]

Depends upon the tree type, size and soil conditions.

Willow on clay and you'd be lucky to be 2m minimum.

[worsy]

My garage is close to trees and a hawthorn hedge. I had to have an engineered raft. The house is 3 or 4 metres from Hawthorn hedge and that had to go down about 2 metres I recall.

[bobtail4x4]

try this

http://www.labcwarranty.co.uk/foundationcalculator...

[Shaolin]

Depends on soil, size of trees and the inspectors where you are.

We had an extension a couple of years ago, there were some trees in neighbours garden. The architect came and saw the site and recommended 900 - 1200 - 1500mm stepped with deepest where the trees were. After the inspectors had been we ended up with 1200 - 1800 - 2100mm. The trees were cut down between the plans being drawn up and building started. Our neighbours are having an extension at the moment, I spoke to him at the w/e, the trenches were dug and he was waiting for the inspectors, sure enough, the digger was in action again making them deeper after they came, there are no trees anywhere near his foundations. I think our inspectors are a bit cautious!

[bobtail4x4]

but people do complain so when the new extension starts to subside.

[Neil - YVM]

V8RX7 said:

Depends upon the tree type, size and soil conditions.

Willow on clay and you'd be lucky to be 2m minimum.

We had one built 3 years ago, Large oak tree about 50ft away, clay soil, and the footing nearest the tree ended up being 2.4 or 2.6m!! with anti heave poly fitted!
This despite original property sitting on 1000mm strip, without a crack in the house.

[foliedouce]

bobtail4x4 said:

try this

http://www.labcwarranty.co.uk/foundationcalculator...

Thanks, that's very useful, apparently I need 2 1/2 metres footing

Thanks everyone else as well

[98elise]

When we built ours, BC wanted 2m (in chalk ground). As above the existing house is on much smaller foundations and has had no issues in the 60 years its been there.

[bobtail4x4]

if its chalk there is no shrinkage, so normal founds can apply,

[foliedouce]

98elise said:

When we built ours, BC wanted 2m (in chalk ground). As above the existing house is on much smaller foundations and has had no issues in the 60 years its been there.

how far from the trees were you and what trees were they?

[Grandad Gaz]

foliedouce said:

98elise said:

When we built ours, BC wanted 2m (in chalk ground). As above the existing house is on much smaller foundations and has had no issues in the 60 years its been there.

how far from the trees were you and what trees were they?

We also had to go down 2m in chalk ground 15 years ago. An ash tree about 4m away and an oak tree in next doors garden. All had to be considered

We had to get someone in to work out depths. The council will need to see calculations to confirm. From what I remember, I don't think the current size of the tree comes into it. It's the size it can grow to which is important.

[anonymous-user]

Also needs tree officer guidance if the trees have Tree Protection Orders (TPOs) on them.

I had to have manually dug pads and then a ring beam for my garage due to TPO trees nearby.

[parakitaMol.]

i am going through this at the moment with our garage, we got an arboricultural survey done first as we wanted to keep the trees, a mix of oak, ash and hawthorn and our planning consultant suggested that planning in our area would be more agreeable for consent if we kept the trees so we were advised to locate the footings 4.5m away from them.

The piling and foundations would use the grid system to allow for root /movement and periods of dry or wet weather.... and we are on clay which is a pain. I am not sure if we will get a full ground survey as this is expensive providing the planning is granted with reasonable constraints.

As has been mentioned - different trees have different requirements as they spread in different ways and consume varying amounts of water.

[Spudler]

foliedouce said:

Does anyone have any experience of building near trees (3 metres away) and what depth of footings where required by building control#?

Building Control will be armed with a chart with relevant trees, distances and depths.

[foliedouce]

Does anyone have experience of overhanging trees? Looking to build an extension with an overhanging canopy. Dug footings and roots aren't an issue

[Zyp]

I have a single storey extension nearing completion that has been built just inches away from an old Yew tree.
Tree was about 300 years old (and rotting) and very tall, we had it felled but the stump is still in the ground.

Building inspector was happy for the builder to dig 2m strip footings (16m total length, so loads of spoil) and to cut off the deep roots.
The last metre down was solid clay.

http://landscape-masonry.co.uk/pdf/layout%204-2.pd...

Edited by Zyp on Wednesday 2nd September 22:56

[moles]

Why do we go so deep now is it because the building inspectors are liable if it subsides so they go over and above to cover themselves or is there more info around on what causes issues?. After all there are loads of houses built in the 60,70,80's that must have been built on much shallower footings and have no issues.

[V8RX7]

moles said:

Why do we go so deep now is it because the building inspectors are liable if it subsides so they go over and above to cover themselves or is there more info around on what causes issues?. After all there are loads of houses built in the 60,70,80's that must have been built on much shallower footings and have no issues.

Three reasons:

If it's overspec and still goes wrong - they can't be blamed (not that they are actually liable anyway)

Thousands of homes (admittedly of millions) so get subsidence type problems every year - particularly when we get a very dry or wet periods.

Relative to the price of everything else, it's very cheap and easy to do at the time and very expensive to correct later

[TA14]

V8RX7 said:

moles said:

Why do we go so deep now is it because the building inspectors are liable if it subsides so they go over and above to cover themselves or is there more info around on what causes issues?. After all there are loads of houses built in the 60,70,80's that must have been built on much shallower footings and have no issues.

Three reasons:

If it's overspec and still goes wrong - they can't be blamed (not that they are actually liable anyway)

Thousands of homes (admittedly of millions) so get subsidence type problems every year - particularly when we get a very dry or wet periods.

Relative to the price of everything else, it's very cheap and easy to do at the time and very expensive to correct later

It is frustrating though. A few years ago I designed the footings for a five storey building then a couple of years later built a garage extension with cavity walls at my own house. BC wanted the footings slightly bigger for my house work - I could hardly believe it. I thought about kicking up a big fuss but decided to pay the extra and not annoy the visiting BCO. One other thing that I noticed was that he wanted the footings a certain distance deeper than the deepest tree root that was found, might have been 500mm.