How To Seal Repair Mortor In Sandstone Fireplace

Q: The mortar joints surrounding the stones in my walkway are aging. Can they exist patched? —Nellie Kurtzman, Mount Vernon, NY

Martin D'Arcy, possessor, DNF Construction, replies: A stone walkway with cracked mortar is an eyesore and tin can go a tripping take chances if water gets underneath and loosens the stones.

The best way to repair these joints is with a sand-topping mortar mix, which is stronger than regular mortar and can handle wider joints. I mix it with an acrylic fortifier so that the joints will be less susceptible to h2o penetration.

The hardest part of this job is chipping out the crumbly onetime mortar without damaging the stones. One time the onetime stuff is out, filling the joints is as like shooting fish in a barrel as decorating a block. Simply continue in mind that while the new mortar won't lucifer the existing mortar color, it volition lighten and blend in over time. The only way to get the same shade would be to supercede all the old mortar, crumbling or not.

Tackle this job only when in that location'south no danger of frost. A two-day dip into the 20s F can ruin fresh mortar.

Step 1

Chisel Out the Mortar

Wearing gloves, safety spectacles, and genu pads, break out the crumbling mortar with a cold chisel and 3-pound sledge. Chisel right down to the setting bed; be careful next to the rock or use a grinder with a diamond blade to carve out hard spots. Make clean out the joints with a stiff-bristled nylon castor.

Step two

Brand the Topping Mix

Pour the dry mortar into a wheelbarrow, and stir in an acrylic fortifier according to the manufacturer'due south directions. Add simply plenty water to give the mortar a sticky, peanut-butter consistency. It should remain workable for almost 45 minutes. Earlier applying the mortar, sponge the stones and joints with water.

Step three

Make full the Joints

Ladle the mortar into a grout pocketbook or a zip-summit bag that has a ½-inch-diameter hole you've snipped in a corner. Squeeze the mortar out in a smooth motion, forcing it to the bottom of the joints. Fill them upward to ane inch deep in one pass, leaving the mortar just proud of the stones. Deeper joints should be one-half filled, packed downwards with the trowel, then topped off. If any mortar lands on summit of the stone, scrape information technology off immediately.

Step 4

Trowel the Mortar

Push the mortar down into the joints using a brick trowel, then roughly tool it to the same height as the existing joints. Scrape off the excess mix and dump it dorsum into the wheelbarrow. Equally you work, dip the trowel in water to proceed it clean. Likewise, sponge-clean the stones with water to prevent mortar stains.

Step 5

Pack it Down

Wait 60 to 90 minutes for the mortar to set up enough to exit a thumbprint when pressed. Using a tuck-pointing trowel, polish and pack down the mortar and so that it matches the acme of the existing joints. Clean the stones as necessary.

Step 6

Castor the Joints

Run a stiff, dry, natural-bristle castor over the mortar in one direction, smoothing away the bumps and ridges left by the tuck-pointing trowel. Stay off the walk overnight. The mortar will fully harden in about a week. If the atmospheric condition during that time is very hot, windy, or dry, continue the mortar moist with wet burlap.