In this video, This Old House landscape contractor Roger Cook resets an uneven bluestone patio.
1. Stretch a mason's line across the patio from top of stairs to house. Slip a short length of 1x3 under each end of the taut line.
2. Use a third short 1x3 as a guide block to check the distance between the bluestone slabs and the mason's line stretched across the patio.
3. If the surface of a bluestone slab isn't exactly ¾ inch below mason's line, pry up the slab with a flat bar.
4. If the slab was too high, use a shovel to scrape away some of the stone dust from below the slab. Shovel the excess stone dust into a bucket.
5. In a wheelbarrow mix six parts of stone dust to one part of cement to create a setting bed for the bluestone.
6. Shovel some setting bed onto the substrate and spread it out with a pointed trowel.
7. Set the bluestone slab back into position and tap it down with a rubber mallet. Use the 1x3 guide block to ensure the slab is ¾ inch below the mason's line.
8. Repeat to check and, when necessary, reset the remaining bluestone slabs located beneath the mason's line.
9. After resetting one row of bluestone slabs, move the mason's line over to the adjacent row and start the process over again. Continue until all the bluestone slabs in the entire patio are even.
10. Pour polymeric sand into the joints between the bluestone slabs, then sweep the sand across the surface, filling each and every joint.
11. Use a leaf blower to blow excess sand from the bluestone surface.
12. Take a garden hose and lightly mist the entire patio, including the sand-filled joints.