"James" wrote in
:

Hi

I have a mature tree at the bottom of my new garden. I think it's a
sycamore (will have a better idea when the leaves grow) and it is easily
over 40 feet high.

I plan to build a garage/workshop on the land under the tree and this is
to include a service well, ie a sunken walkway in the floor of the
garage, so I can walk under a parked car to service it, rather than have
to elevate the car on ramps etc.

The pit will be about 6 feet deep and 3 feet wide and I wonder if
digging it will affect the tree.

I hasten to point out that not only is the construction of such
a pit very expensive (you can buy an automobile lift for less)
but they're dangerous in several ways.

google "car lift" uk 62,600 hits

The only service pit installations of which I'm aware in the
US over the past half century are in quick oil change shops
and some large trucking company depots where pulling a tractor
and semitrailer over a pit is sometimes advantageous.

Make certain your insurance remains in force if you build one
of these anyway.

I'm looking for information on the size, depth and spread of tree roots,
so I can gauge the likely impact of digging the foundations of the
workshop and the service well.

Can anyone point me to a site with this info, or do you know how deep a
sycamore sinks it's roots, and how far from the trunk they extend?