Hi Frank:

I noticed your mention of expansive soil - an engineering term. I
have some understanding of geotechnical engineering problems
associated with expansive soil - did some consulting in Asia where it
was causing big time problems with rail road embankments during
monsoon ..

Expansive soil can and does cause structural damage to buildings if
there is insufficient recognition of the problem during design. In
your case, if the water causes the soil to expand in a way that was
not anticipated, then yes, damage can occur. In your area there is
probably a recognition of the problem and building practices may be
such that these problems can be accommodated. I would not speculate on
what damage could occur not knowing the technical details. A local
geotechnical expert in you area can however.

Another problem that occurs with trees is *reduction* of the
groundwater from evapotranspiration in clay soils, consequent
consolidation of the clay stratum, and settlements of the structure
founded on the stratum. This is usually associated with large trees
like oaks so a relatively small pear tree may not apply... The thing
is, you neighbour by watering may be balancing the equation.

As for root barriers - that is a new one to me. I would assume it
woud be a costly solution for you - you better make sure there is real
danger of damage. But as I have hopefully indicated, you might have a
legitimate concern. Please let me know how this turns out.

Hedley in Canada.

***

On 18 Jul 2004 16:58:36 -0700, (Frank)
wrote:

I have a neighbor who decided to plant an Aristocrat Flowering Pear
Tree about 5 feet from our property line and about 17 feet from my
foundation in highly expansive clay soil that is watered almost year
round: in Califorina where we go long spells without rain. I have
water lines and sprinkler lines within feet of that tree, and a water
line about seven feet from it.

One of my concerns with this tree is potential root damage to my
home's foundation, concrete driveway, and anything I decide to put in
that area in the the future.

I've been researching root barriers, and the one idea I'm debating is
putting in a 4 to 6 feet deep (below ground) rebar reenforced concrete
wall along our property line to keep this tree from damaging my
property. Does anyone know how effective root barriers are at
different depths in the soil?