Building Regs for Extension

scaredofdebt

Hi,

We're having a small extension built, single storey, 5 x 4 metres.  We've been told by the builder we don't need planning permission due to size, height etc.

We had the building regs guy around yesterday, he says that due to a tree being within 10 meters of the foundations, they need to be deeper, currently 1m deep, neeed to be 1.2 metres, that's not an issue.

However, he's also said we need to remove a hedge that goes down the side of the garden, made up of small conifers, the nearest point of this is about 2 metres from the corner of the foundations but we need to remove at least 9 meters of the hedge (and replace with a fence).

Is this normal?

I understand there is a risk of the roots damaging the foundations, but most of our neighbours have similar extensions with hedges close by.  It's going to be about £2,000 to replace the hedge with a fence so would rather avoid the cost if possible.

We live in County Durham, not sure if the rules vary by region.

Thanks for any suggestions or advice.

David

stuart45

Have a look at the NHBC calculator. http://nhbccampaigns.co.uk/landingpages/techzone/previous_versions/2011/Part4/section2/appendix.htm#42CT14
It's what Building control use as a guide for foundation depths when building in shrinkable clay and trees nearby.
Unfortunately they take the mature height of a small tree, although it might work out cheaper to replace the conifers with a low growing, low water demand type.

scaredofdebt

Thanks.

Those tables assume the tree height of a minimum of 8 metres, the hedge is 2-3 metres at the tallest and it's 40 years old so no way will those trees grow to 8 metres, I think the building regs guy thought they were Leylandii or something.  I'll identify the exact type of tree and give him a ring, even if there were 8 metres, worst case scenario is we need to dig down to 2 metres for the foundations but the hedge can stay.

stuart45

Well worth checking it out with him. Do you know if your clay is a high, medium or low shrinkable type? You can get it tested if the BCO is assuming it's high, although they should have an idea if they know the area.

scaredofdebt

It is clay and I think he said it was highly shrinkable, I've assumed that when using the tables you linked.

He said we'd need a structural engineer due to the depth of foundations he was talking about (over 2.5M) so we were looking to get the hedge removed instead as I suspect such work is going to get expensive very quickly.

I'll get the trees identified and take it from there.

Thanks for the info.

FreeBear

scaredofdebt said: He said we'd need a structural engineer due to the depth of foundations he was talking about (over 2.5M) so we were looking to get the hedge removed instead as I suspect such work is going to get expensive very quickly.

Ground works to that sort of depth is going to cost way more than a new fence. And if you are going down 2.5m+, I'd be looking at digging the whole lot out and going for a cellar - Done right, you'd have somewhere to store wine & stuff...

scaredofdebt

Yeah it's just going to be too expensive, it's either get rid of the hedge or dig deeper foundations but not so deep as to need a structural engineer.

We've identified the trees using an app (not sure how accurate it is) and it says they're White Cedar.  Now these are only "moderate" water demand trees that typically grow up to 15 metres so we should be OK to keep them and dig the foundations deeper, about 1.7M by my calculation.

What a minefield.

As if the neigbours would allow us to grow the hedge to that height and as if we'd do that, we trim them back every few years so they never get over about 7 feet.

TELLIT01

£2k for 9 metres of fence is extortionate even if the cost of removing the existing hedge is included in that price.  9 metres is only 5 panels.

scaredofdebt

Yeah we will need the whole hedge taking out so it's going to be more like 18 metres and we were wanting a more bespoke fence but it might have to be panels depending on cost  Got someone coming out to give a quote later today.

It will look odd I think if we just have a fence and then half a hedge down the boundary but maybe not.

Slinky

We had to go down 2 meters+ because of the neighbours' leylandii hedge which was a meter from our extension. Several years later they decided to get rid of the leylandii as they didn't want the expense of maintenance anymore. So we ended up paying out to put in the deep footings, and paying out for a new fence as the boundary was our responsibility. They did offer to pay something towards the fence, but we decided that would open up another minefield when we eventually sold the house.

scaredofdebt

It sounds like the builder has spoken to the regs chap and agreed we can just get the foundations a bit deeper, 1.7m in total which is costing an extra grand.  I need to confirm (it's my wife who spoke to him) that the regs will get signed off and we're good to go.

Fencing guy quoted £1,350 to remove the hedge and put in the fence but that's for a feather edge fence, he strongly advised against panels as we are quite exposed here so it wouldn't last long is what he said.