How do I repair mortar joints in flagstone?

Answer by  willywager (52)

Use a grinder or hammer and chisel to remove any excess old mortar. Use a broom to sweep out the joints, dampen the joints with water from a sprayer, put the mortar into a grout bag, fill the joints,allow to dry until they can be finished to the style needed.

Answer by  emtrobstu (233)

To repair the mortar in flagstone you need to get some mortar mix. This typically comes in 60lb bags and you add water to make the mix. For small jobs use a ready made mortar mix and just pour it on the crack.

Answer by  eyeguy (3760)

Use a polyurethane joint compound filler. You can add color if you wish. Apply with a caulking gun and let dry.