Root protection zones and existing buildings.

[Tom D]

I have been asked for advice on some trees near a proposed development, There is already a building on site, the footprint of the new development is entirely within the footprint of the existing structure. It is also within the root protection zones of two trees one of which is in perfect health and will almost definately have to stay.

 

So given that the RPZ's are already built on is there a requirement to consider them with the new building?

The logical answer is no.

My gut feeling is no.

But does anyone know the official line?

 

Thanks in advance.

[PhilBeech]

They will almost certainly be at risk during demolition and construction. You need to think about access and egress to the site, storage of materials etc.

 

Appropriate protection will be required for the duration of the construction phase.

[Tom D]

So can I site buildings within the RPZ?

[Paul Jenks]

You'll need to take a look at the BS5837:2005. See if someone you know has a copy. It's a bit pricey. From memory it's over £100.

Usually, the existing foundations, slab, paving etc have to be lifted using handtools with an arboriculturalist present to effect correct pruning of exposed roots. Sometimes the LA doesn't like stuff to be moved when it's within the calculated RPA.

You'll also have to consider the future growth potential of the trees and the shading. Pruning the tree to shoehorn a building in and the future pruning or management pruning to retain the size of trees close to a proposed building is not looked upon favourably.

Read the document to get a feel for the BS, British Standard as opposed to B**l S**t.

Then speak to the Tree Officer and see what his view is.

[Tom D]

I have the BS, I am just being lazy, I have never come accross this situation before.

[ScottF]

Like Phil said above, you should be able to exclude the building footprint from the RPA, but remember that you'll need to make the rooting area up elsewhere )i.e. you're assuming an offset of the radial RPA. The danger, as Phil points out, is the demolition phase. Also, it's unlikely that the new building will use the existing foundations exclusively, so study the as existing and proposed and look for the changes. Obviously, don't assume the services are all in and not to be changed since sewerage may need to be upgraded, broadband cable etc may be required.

 

Just look at the site plan and think of where you're going to put your tree protection fencing, too. Is there enough room to implement the development?

[Tom D]

I understand all the above points, however in this situation the existing building is very close to the trees, any new development will be well within the RPZ. As the trees are part of a group there is no scope for bending the RPZ.

 

The basic questin is: either the RPZ still applies and therefore no development can take place or it doesn't apply and its good to go so long as it remains within the footprint of the existing structure.?

[Paul Barton]

How about doing a bit of root investigation (e.g. air-spade) along the edge of the existing building to quantify what roots are actually there?

 

Although the new building will be within the normal RPA as suggested by BS5837 it is down to the arb to judge what effect the development will have on the trees. If there are only a few small roots adjacent to/under the existing building you could argue the development can go ahead. If you do you would need to write a pretty robust method statement to demonstrate how the trees will be protected though.

[Tom D]

So there's nothing official to deal with this situaton? It's down to me to make a case either way?

 

TD Tree & Land Services Ltd.

[PhilBeech]

That's consultancy for you! protect the trees to the best of your ability. If you think, looking at the plans, there is no way to save them then the and need amending or the trees have to go. Specify re-planting as mitigation.