Replacing a retaining "wall" in a root protection area

Replacing a retaining "wall" in a root protection area

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Sporky

Original Poster:

1,897 posts

31 months

Friday 18th June
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Hello - wondering if the collected expertise here can save me undue complication.

Our house is built on a steeply sloping plot. At the front, about 50cm back from the boundary and pavement, there is a retaining wall so that the front garden is flattish. It appears to have been made by putting in a mortar base (foundation would be overstating it), then pressing treated wood sections into the earth. Twenty years later we bought the house; the bits of wood are understandably rotting away and falling off.



The plan is to replace it with a bit of blockwork and then some stone to match the house and the retaining wall by the drive, but our builder says (and I've no reason to dispute this) that it needs a proper foundation. This is where it gets fun; most of that timber bit is in the root protection area of next door's tree.

We did an extension into the RPA with planning approval, but it meant helical screw piles and a lot of discussion with planning and the tree people. I'm not going to do anything dodgy, so how do I ask planning if I need planning permission? They have a pre-advice option but it's a surprising chunk of money for something that surely has a simple "yes you do" or "no you don't" answer.

Jeremy-75qq8

296 posts

59 months

Friday 18th June
quotequote all
Given it will be permitted development by way of it size ( less than 1m looking at it) I am not sure planning will have any interest.

They do look at RPA if it needs a planning application - but I dont think you do.

Your main risk will be if you damage the neighbours tree and they want restitution.

I would ask an arbercultualist as some trees have deep roots and some shallow - so you maybe able to dig an acceptable foundation and then just bridge with a lintel over any large roots.

You can also get retaining wall lego blocks that require little or no foundation - the slope upwards to the front is not flat.

Sporky

Original Poster:

1,897 posts

31 months

Friday 18th June
quotequote all
If we damaged the tree the neighbours would be overjoyed - they've wanted rid of it for years, but it's healthy.

I'd think the tallest bit of that wall is about 80cm, so it sounds like we should be safe, but I'd guess a certificate of lawful development might be worthwhile.

Jeremy-75qq8

296 posts

59 months

Friday 18th June
quotequote all
Unless you are in a conservation area or the tree has a TPO on it they can just cut it down.

You didn't mention either in your post.

If it does have a TPO then upsetting it is a criminal offence. ....

Sporky

Original Poster:

1,897 posts

31 months

Friday 18th June
quotequote all
Ah - sorry. The tree does have a TPO - I'd thought that was implied in the mention of the RPA but I should have stated it explicitly.

Jeremy-75qq8

296 posts

59 months

Friday 18th June
quotequote all
Then I would get an arbercultiralist to take a look and advise on an acceptable foundation that would not damage to roots.

The bill will be daft but such is life.

Some trees have shallow roots. Some don’t etc

Equus

11,332 posts

68 months

Friday 18th June
quotequote all
Sporky said:
...They have a pre-advice option but it's a surprising chunk of money for something that surely has a simple "yes you do" or "no you don't" answer.
Jeremy-75qq8 said:
Given it will be permitted development by way of it size (less than 1m looking at it) I am not sure planning will have any interest.
If it's a TPO'd tree, the arse-covering solution here is to submit a 'Works to Trees' application and describe the works as something like 'reconstruction of existing retaining wall with new foundations, within root protection area of TPO'd tree'.

This type of application has no fee attached to it, so it won't cost you a penny.

The slightly less official alternative is to simply give the Council's Tree Officer a ring... unlike Planning, because they know they'll have to deal with any application F.O.C., they're usually more than happy to come out and give informal advice (it's in their own best interest, 'cos it might end up avoiding them the need for the paperwork of a formal application).

Notwithstanding the above, note that retaining walls can constitute 'engineering works', requiring Planning, even if they are less than the 2/1m. height allowance for 'normal' walls and fences, depending on how much much you're shifting. The traditional rule-of-thumb is that if it involves shifting more muck than one man with a shovel and a barrow can shift in an afternoon's work, then it is not 'de minimis' and can be considered (in theory at least) to be an engineering operation.

Sporky

Original Poster:

1,897 posts

31 months

Friday 18th June
quotequote all
Thanks - I've talked to the tree officer before, and he was most helpful with the extension. I'll give him a ring on Monday.

aeropilot

24,685 posts

194 months

Friday 18th June
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Build the new retaining wall using gabions instead. They can just sit on a relatively thin base.

Sporky

Original Poster:

1,897 posts

31 months

Wednesday 14th July
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Equus said:
The slightly less official alternative is to simply give the Council's Tree Officer a ring... unlike Planning, because they know they'll have to deal with any application F.O.C., they're usually more than happy to come out and give informal advice (it's in their own best interest, 'cos it might end up avoiding them the need for the paperwork of a formal application).
Took a while to find him, but the Tree Officer came over this afternoon, had a look, I ran through the plan, and he said we're fine to get on with it. I also have an email response from the planning officer who oversaw our extension saying that it is not a planning issue as it is the repair or replacement of an existing wall. She said we could apply for a certificate of lawfulness if we wanted, but that she was happy to put it in writing that this was not required for the work.

Now I just have to get the builder to quote for the thing, and to turn up at some point to do it...