Chocolate Flagstone Warping
by Peter Heikkila
We installed 1-1/4" Chocolate Flagstone over a 1/2" Type S mortar bed over a concrete slab on a patio. Everything was level when we left for the day. The next morning, the stone edges had peeled/pulled up, causing everything to be out of level. I've attached pictures. It's like the stone warped over night. What can we do to stop this from happening? Help!