2 x 4's inside the hearth slab

[masuzzu]

While building the hearth slab , I left a 2x4 inside the slab. It is now inside the slab (covered by concrete). Will this compromise the slab, since it is of a different material (with possibly different expansion coefficient?)
Thank You!

[Michael Craig]

Re: 2 x 4's inside the hearth slab

Only if the wood gets wet. Wood fibers will expand with great force if enough water gets to the wood. Since it is burried in the slab, it should be sealed off from water enough so it should not expand enough to break your slab. Even if it does crack, your stand will cover it up and should not matter. On the bright side, when you poured your concrete the boards should have absorbed as much water as they ever will from the concrete itself. This being true, the boards should only shrink with time. You should be safe, Good luck and Good building.