Building Garage over tree roots

I think if you post your state you will get a better answer based on freeze lines.

If you want to see what a tree root system can do to a garage slab. I can post some pictures tomorrow when I get home.

The original owners of our house planted two Soft Maples in the backyard. The one that is between the Kitchen and Garage is larger and has actually heaved the garage slab in the middle. Lets not forget that it also makes for tough digging when I had to replace the electrical run from the house to the garage.

tjfslaughter said:

I think if you post your state you will get a better answer based on freeze lines.

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Frost line is not the bad part. It is the tree. Majority of states that have a deep freeze, it can be anywhere from 3 to 6 feet. My area uses Block foundations and poured. The blocks get filled in the cavities as you lay it. It comes out about the same.

How big was the tree. I would just bring in an excavator or rent one for the day and get it out. So you don't have to worry about it.

You could use rebars in the slab over the area where you suspect the roots may be. Maybe thicker slab there. If you try to dig it out, I think more work repacking the earth.

You might find this article on Frost Protected Shallow Foundations interesting.
http://buildipedia.com/aec-pros/construction-materials-and-methods/slabs-for-colder-climates-part-1-the-how-and-why-of-frost-protected-shallow-foundations

I do not worry about the decomposing roots under a slab that has a good sub grade preparation. The shallow roots are removed as part of the excavation. The deeper roots below your select backfill rarely, if ever, cause subsidence problems.

Thanks for all your help. We have found a way to put it behind where the tree was so we can avoid most of the problems. Now to rent a backhoe and move TONS of dirt and get it tamped down! Yikes!