re: Live Oak roots above ground, slab threat?

I’m no arborist or anything but if the tree is truly 15 ft away I’d think you’d be easily fine OP. I’d worry if it’s 5-10 at most. 15 ft is a good distance for a root big enough to remotely cause any issues especially for a younger tree. If you are talking a 50+ year old tree maybe worry but I think that root guard would be more than adequate for your situation also.

I’ve got a live oak that has caused driveway issues for me but it’s like 2 ft away and I have another on the other side that’s 4-6 ft away that hasn’t done anything. Both are 18-24” diameter trees.