How To Repair Cracked Mortar Between Blocks

Even the most beautiful brickwork is just so much rubble without a bed of mortar to seal and concur it together.

What Is Mortar Repointing?

When mortar starts cracking, receding, and falling out of the joints, it'due south time to chisel out the quondam stuff and trowel in the new, a procedure called repointing. This is a simple task, merely it has to exist done with care, using the correct tools and the right materials to avoid damaging the brick and permanently compromising the integrity and appearance of the wall. For me, that means using hand tools and lime mortars similar to the ones masons employed 100 years agone.

Tin Yous Mortar Over Old Mortar?

If your brick is l years quondam or less, you can probably repoint information technology safely with modern, portland cement–based mortar (although the guy doing the next repointing, who'll have to grind it out, may curse your decision). Just if your house was built before World War II, the mortar is probable a mix of lime putty and sand, and you should try to match it. Otherwise, over time, as the soft old brick swells and shrinks against the rock-hard mortar, the bond between them volition break, moisture will become trapped in the wall, and the brick faces will start popping off. Traditional lime mortar acts similar a cushion, flexing with the brick'south motility while allowing wet to drift easily out of the wall.

A restoration mason can analyze sometime mortar and make a compatible mix, or you can send mortar samples to companies such as U.S. Heritage and go a custom blend with the same color and characteristics. Yous can choose between hydraulic lime, which comes in numberless and hardens when it reacts with water, much like portland cement, and lime putty mortar, which comes in buckets and slowly hardens by reacting with carbon dioxide in the air.

How to Mortar Bricks in 6 Steps

Step 1

Rake Out the Bed Joints

Scrape out the horizontal joints to a depth of at to the lowest degree ¾ inch. (Joints wider than ½ inch have to be deeper: 2½ times the joint's width.) A carbide-tipped grout saw works well on these ¼-inch-wide "butter joints." (On wider joints, use a common cold chisel and an engineer'due south hammer.) Avoid electric angle grinders. Unless yous're trained to employ them, they're nearly guaranteed to cut into and disfigure the brick.

Step 2

Clean Out the Head Joints

After removing three or 4 courses of bed-articulation mortar, dig out the vertical joints. Be careful not to striking the edges of the bricks above or below. Hither, the old mortar is being chiseled out by tapping a five-in-i painter's tool with a hammer.

Step 3

Launder Down the Wall

Person washing brick wall to prepare apply mortar.

Whisk away all the crumbly debris with a potent-bristled brush, then check that the blade of your tuck-pointing trowel volition fit into the joint. If the bract is too wide, grind it downwards with an annoying bicycle. Mist the wall with water until the brick is thoroughly clammy and starts to baste; this is a critical step because dry materials volition suck the moisture out of the new mortar and prevent it from curing properly. Wait until the side by side day earlier filling the joints.

Step iv

Mix the Mortar

Mist the brick again. And then, following the directions on the bag, stir h2o into the dry mix until it reaches the consistency of peanut butter and clings to an upended trowel. Expect until a motion-picture show of water forms on the mix, nearly 15 minutes. Stir the water dorsum in. The mortar is now ready to apply and remains workable for 8 hours. If information technology gets likewise dry in that time, you tin "retemper" it occasionally by adding h2o.

Step 5

Make full the Joints

Scoop a dollop of mortar onto a brick trowel or hawk, agree it upwardly fifty-fifty with a bed joint, and push the mortar against the back of the joint with the tuck-pointing trowel. Eliminate voids with a few slicing passes of the trowel's edge, so add more mortar until the joint is filled. One time you've finished three or iv courses of bed joints, go back and fill the head joints. Finally, polish and compact all the mortar with the trowel'southward flat confront and scrape the excess mortar off the brick.

Pace 6

Brush the Wall

Person brushing brick wall with stiff bristle brush.

When the mortar is firm to the affect, castor diagonally across it to remove any dry mortar crumbs. (Brushing in line with the joints tin can pull out the fresh mortar.) Then carefully sponge mortar rest off the brick faces. For the next three days, use a tarp to protect the soft joints from the sun, wind, or hard rain, and give the wall a daily misting to continue the brick and mortar moist.

Tools Y'all'll Need

Source: https://www.thisoldhouse.com/masonry/21016676/how-to-repair-mortar-in-a-brick-wall