I know this is a recurring thread, but I've encountered a situation where a local resident (and her "foundation expert")are blaming two street trees for foundation cracking. We are in the midst of a 2-year drought and, while I realize that trees and other vegetation will draw water from soils, especially the clays used for bldg. subgrades, in this case I am contending the the extended drought has effectively drawn down the water table in the entire area and that it is not possible to blame these 2 Bradford Pears (10" cal.)for this case, as the trees are a good 20-25 feet from the building. Any thoughts (other than "why the bother over 2 Bradfords")?

Reply to post by Steve Shurtz, on September 08, 1999 at 16:31:20:

What are the tree haters proposing? Removal? If so, they should prove that the trees are responsible rather than having to prove that the trees are not repsonsible.

Are these public trees? Who is in control of their fate?
Hopefully, not the tree haters.

Tom

Reply to post by Steve Shurtz, on September 08, 1999 at 16:31:20:

If you're in a public sector roll you might well take on some burden of discovering and demonstrating the real facts lest this one homeowner provide example for many others.

A few question or suggestions:

The cracking is from subsidence? and it's concurrent with the recent drought?

Is there cracking on this or other foundations with no trees involved? What are the differences in soil moisture with and without trees?

Only way to know for sure the roots CAN'T be involved is to test dig and see if there are any there. If they are there you can't use that defense, you'll have to otherwise determine or estimate the contributory effect of the roots.

Reply to post by Steve Shurtz, on September 08, 1999 at 16:31:20:

I am public sector, do have authority over the trees, and am refusing to remove the trees.

My thought is that, even if roots are present near the slab, in the absence of any heaving or direct physical root damage, which does not appear to be present in this case, the mere fact that roots are there shouldn't implicate the trees.

I suspect that what we have is a poorly prepared subgrade and/or a poorly built slab.

I'm looking for info (or comments) which supports my contention that the "general" water loss over the entire neighborhood is responsible, rather than the two nearest trees.

Clearly, they'll have to prove that the trees are at fault before I'll authorize removal, but I may wind up in court on this one and would like to start gettin' my ducks in a row.

Reply to post by Steve Shurtz, on September 08, 1999 at 16:31:20:

sounds like a perfect use of the air gun to perform an easy root excavation without harming the tree....
verytreelylew

Reply to post by Steve Shurtz, on September 08, 1999 at 16:31:20:

Arboricultural Journal, Nov. 1998 would be the source of much literature on the subject. Lew's idea is reasonable. A person could just dig a trench between the tree and the foundation and look at the sum diameter of the root cross sections. Peter