Extension near a TPO tree - how do I stay compliant?

25 Jul 2007
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United Kingdom
Apologies for the long post, but I'm unclear on how to plan and progress with a simple extension.

I'm looking to build a pretty straightforward full width rear extension - single storey, 3 m deep x 8 m wide, two sets of bi-folds, roof lantern etc, very simple. We're pretty certain it can be built under PD, but will be applying for a certificate of lawfulness all the same. The only issue is that we have a mature beech tree 10 metres from the existing rear of the property which has a TPO assigned to it. Our architect advised getting an arboriculture consultant to assess the tree, which we have, and he said there would be some roots within the area we want to dig the ground works in, but these would be small and could be trimmed back by a professional. He has suggested he perform a BS5837 tree report. He didin't think it would be worthwhile doing an air spade investigation as the extension boundary will be a decent distance from the tree, but it may need monitoring when doing the foundations.

I understand when doing a PD, we could just crack on and start building, having given building notice first. However, we don't want to impact the tree mainly because it could cost us a large fine, but also because it's a really nice tree!!

My questions are, what's the best process for staying compliant, and who needs to be involved at which stage to help mitigate issues? Do I submit the certificate of lawfulness and include the tree report, or is the tree report not required at that stage? Would the tree report raise alarms that would then make the council request it's put through full planning? Will building control want to see that the foundations haven't affected the roots of the tree and if so does that mean having the arboriculture consultant on site to monitor their digging by the builder? Will a builder care about the tree roots and be sympathetic to planning the foundations? The architect has said the extension is so simple it wouldn't need building regs drawings, but should we get him to do regs drawings which take into account the roots and design accordingly - screw piles perhaps?

Lots of questions, sorry!! Thanks.
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Building control will only be interested if the tree will impact foundation stability.

They aren't concerned with the preservation of the tree, that's a planning matter.

From memery beech is a low impact species, but if you do a search you should be able to confirm - I think LABC have a tree / foundation depth calculator online.

Sounds like your extension will be about 7 metres from the tree?
That's right, 7 metres will be the closest point.
A tree report would cost a fair bit, wouldn't surprise me if it was higher than any potential fine.

At 7 metres though I'd be surprised if it was a problem.
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What damage to a tree do you think extension work will cause?

Somewhere between nil and zero.
TPO damage is a fine up to £20,000 or a tree report is £500 - so a fair difference!

I also think damage would be limited, but if the digging of the ground for foundations damaged the roots that then killed the tree, the council would say it's my fault and I'd be fined. Therefore mitigating the blame to say I did everything above board is the route I want to take.

So being a planning issue, it sounds like I should get the tree report and submit with the certificate of lawfulness, which shows willing on my part, and then see if the council comeback with any restrictions/further requests.
digging of the ground for foundations damaged the roots that then killed the tree
Absolutely no chance of that, unless you hacked out three main routes right up to the trunk and the tree fell over.

A LDC is not concerned with trees and any report won't even be considered. But once this report is filed anyway by the estates department, anything at all wrong with that tree in the future will be potentially attributed to your work.

Also what will happen it's that you are then committed to carry out the over cautious advice that will be in any report you get, because you will have been made aware if it. So then prepare to spend a lot more that just the cost of the report.
This has all you need to know.


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