Leylandii hedge 1.5m from proposed exterior wall

[Jon000000]

I am planning a two storey extension on the side of my property and I'm concerned that building control will make me dig very deep foundations due to these trees.
I have not yet spoken to building control as I'm not sure whether to chop down the hedge first, so as not to draw their attention to it, or just get on and speak to them.

The hedge is about 3m high and is on the edge of my property.
The exterior (stone) wall of the extension will be about 1.5m from this hedge.
I think ultimately I want to remove the hedge anyway, can anyone advise on whether to get rid of it first or speak to the building regs people beforehand.

Our neighbours on the other side of this hedge recently built a similar extension but apparently building control weren't too bothered about the trees, although they did have to get soil samples taken and studied by an engineer for some reason.

Thanks in advance for any replies!

 

[Shytalkz]

If you're on clays, then moisture extraction by the roots will have an effect on the behaviour of the clay. The depth of foundation required is a function of the species/water demand, distance from foundation, mature height and soil shrinkage potential. That is why soils were tested next door.

3m high leylands, if removed, will not require anything other than a nominal increase in foundation depth to around 1.2m or so. If remaining, the depth will be a fair way: at 1.5m depth, you are looking way in excess of 2m. Whether trees are removed or not, the proximity of the trees will necessitate heave protection to the foundation sides and under the slab.

If you're on sands and gravels, then none of the foregoing applies directly and you can put your founds in at a depth of 600mm min.

However 1.5m distance of the trees means that you will have to keep to regular pruning of them, to prevent damage to the superstructure as the trees grow. Plus, roots can get into drains and cause problems there.

On balance, it would therefore be prudent to take them out now and put a fence in.

 

[Jon000000]

Our soil does have a high clay content, I should've said.

Thanks, that's helped with my understanding and I think you're right, I'll take them down now. Not sure how easy that'll be as I'll want to get enough of them out of the ground to be able to put a path down below dpc level on the wall, still it'll be a good job to get stuck into!