The message
from David contains these words:

I don't know whether this is an appropriate question for this NG, but I
don't know where else to post it. If someone has a better recommendation,
I will be happy to take it there.

I have a suspicion that tree roots are stressing the foundation of my
house. However, the symptoms are not constant -- they vary with the time
of year.

My question: In general, do tree roots grow at different rates during
different seasons of the year?

No, but they have a different effect on soils and foundations at
different times of the year, which fits your symptoms.

For instance, in winter a deciduous tree has shed its leaves, and
therefore its roots suck a lot less water from the ground. In summer,
the same tree is covered in leaves and making new growth above ground;
so it requires a lot more water. When it sucks a lot of water out of the
soil, the soil is drier, and shrinks. Soil shrinkage around foundations
can cause the building to move and settlle, showing cracks at stress
points.

After the foundations have moved slightly in dry soil, if clay soil
is suddenly re-wetted (by heavy rain in autumn, or the removal of the
tree) it expands again, (called "heave"), putting more stress on the
weakened foundations. For that reason, if one suspects that a tree has
caused foundation movement, it's essential NOT to cut it down right
away. Depending on soil type and local climate, often such trees have to
be reduced slowly, over a year or two, but it's a judgement that needs
to be made by a qualified surveyor.

Don't try a DIY remedy on the tree until the problem has been properly
assessed by an expert.

Janet.

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