Lesser of two evils.

[roythegrass]

I have a mature oak tree close to the house. It has fungus at the base with rot in the trunk.
An arborist has indicated that for safety reasons the tree will soon need felling.
However we’re on clay soil and reading surveyor’s advice online they suggest removing the tree could cause heave with damage to foundations due to the ground re-hydrating.. That said I’ve read conflicting arguments from surveyors and arborists both agreeing and disagreeing with this observation.
Thoughts?

 

[Raintree]

Remove the hazard tree, soil rehydration won't kill you.

 

[Del_]

A living tree is going to produce more 'heave' than no tree.

The living tree makes the dry times even dryer. And when there is enough rain or ground water to super saturate the soil, the tree makes little to no difference.

I question what you are reading as advice from surveyors.

But then again, I didn't realize that surveyors were into that sort of thing.

Question all advice!

 

[sean donato]

I'd take the tree down as well. If tour worried about the soil, and what it may do, the county agg extension office or a local home builder would both be more helpful then a surveyor imo.

 

[pdqdl]

All good advice so far. Say goodby to the oak.

Logically, it makes no sense that removing a tree will adversely influence any hydration of the ground so as to damage a foundation. As a tree grows into an area, it increases the volume of the soil by absorbing carbon and injecting live tree roots through the clay, which is usually somewhat stratified. When those tree roots begin to decay, they will diminish in volume, earthworms and other organisms will begin to penetrate the clay soil in places previously inaccessible. Water percolation will have been increased into the area, and the soil will have been improved by the tree's presence. The only problem the tree would have been causing was the compression against your foundation by it's continued growth.

With the tree gone, the ground might actually re-hydrate a bit quicker following a drought; that is generally considered a good thing. In my experience with clay soils and foundation damage, foundation damage is most prominent during extended drought and the recession of support by the shrinking clay soil. Trees suck water out of the soil. Absence of trees reduce that problem. As Del pointed out, when the water is available in abundance, the tree's presence doesn't affect the water table.

I live in Clay County, Mo, by the way. We know a little bit about clay soil here, 'cause we got lots of it!