Stumps under slab

[Don in LA]

My son is planning a 30'X40' workshop with a concrete slab. He has cut down 3 pines from the site and one water oak. The trees range from 10 to 18" in diameter. He is debating whether to leave the stumps and place about a foot of fill over them, grind the stumps, or remove the stumps. Of course, leaving the stumps would be the easiest option but I was concerned about the stumps rotting and eventually leaving a void under the slab. The slab is being placed over sand---the entire area has about 15' depth of sand. Also, there is a 12" water oak which will be about 6 to 8 feet from the slab. I think that the roots could cause problems with the slab down the road. Opinions?

[edlegault]

Lots of rebar and concrete thickness??

[Tig]

The price and/or effort of pulling three stumps is insignificant compared to the price and effort of building a 30 x 40 shop. I would remove them.

[trihounds]

I would (and have) pulled the stumps under anything I build.

[vwnotrunning]

Unless you will have sufficient footings/piers to suppor the building and reinforcement to allow the slab to be supported on the foundation always remove any compostible materials. It is usually cheaper to remove than reinforce.

[300UGUY]

I had a backhoe remove the stumps when I built the barn. I would not build on top of the stumps, eventually it will cause problems.

[tractchores]

Having burried stumps and built on top (just a shed), i can tell you that every piece of wood will become a void and lead to issues. Far better and cheaper to remove them now.

[crazyal]

I would remove them. The last thing you would want is a void that could get filled with water that you'll need to deal with down the road.

[BeezFun]

Also, there is a 12" water oak which will be about 6 to 8 feet from the slab. I think that the roots could cause problems with the slab down the road. Opinions?

Roots don't seek dry gravel under a building, they look for moisture. I don't see how roots from a tree that far away could be a problem. If it dies from the construction you might want to take it down so it doesn't fall on the building, but if it lives, hey that's more oxygen in your yard to breathe.

On the stumps I think grinding them down to the root line would be sufficient and less disruptive to the soil. If you pull a big stump, you're going to have to do a lot of compacting as you add the fill.

[Egon]

A few trees in the workshop may be handy for hanging stuff from!