How To Repair Cracked Brick

Synopsis: Bricks and mortar crack with time. In this commodity, veteran mason John Carroll delves into the tools and techniques for repairing damaged brick masonry, including how to match the colors of new material to old, the type of mortar to use, and how to repair a brick without replacing information technology.

Editor's note: This article was written before OSHA released their guideline nigh the dangers of breathing in silica dust when cutting or grinding masonry. Be sure to protect yourself, your coworkers, and your clients if y'all take on a project like this.

In that location are a lot of reasons people choose brick for a building material. Information technology doesn't provide an countless buffet for termites or serve as a building site for carpenter ants. Woodpeckers do not delight in drilling holes in it. It's dimensionally stable, doesn't rot or burn, and never needs to be painted. With all these things going for it, though, brick has an Achilles heel: It'south difficult and inflexible, and it cracks under sure conditions.

Whether the cracks are caused by movement, insufficiently filled joints, or simply besides many decades of being exposed to the weather, the owners of brick houses in Durham, N.C., often call me to set them. The reason they call me is considering I do more than slop mortar into the cracks. I make an effort to friction match the color of the existing mortar, and when bricks are cracked, I repair the cracks with mortar dyed to match the color of the bricks. I as well prep the surface properly, employ the right mortar, and continue the joints as neat equally possible. After packing the joints with mortar, I tool them to lucifer the profile of the joints on the residue of the wall. My goal is always to brand the cracks disappear.

Why brick cracks

Masonry structures fissure for several reasons. The first is considering the ground or slab the masonry rests on moves. (Many older houses don't even accept what we'd consider footings today; the structural brick wall rests directly on the soil.) The first building material is not the basis but the soil that it bears on. Footings should be placed on virgin soil or soil that has been mechanically compacted to reach the proper bearing capacity.

Water can cause some otherwise sound soils to become soft and plastic, reducing their begetting chapters and resulting in differential settlement that cracks the basis. Saturated soil that freezes can push button sections of a footing up, or it can push button laterally on a below-grade masonry wall. Another problem is that structures such as foundation walls and retaining walls are often underbuilt. Masonry that'due south subjected to strong lateral forces, such equally those imposed by soil, should be reinforced with steel.

A well-planned organization to drain water away from the foundation is essential. But the work of even the well-nigh careful builder can be undone later past changes to the grade around the house. Landscaping that piles upwards mulch and clay a few anxiety from the house often holds water that soaks in and eventually causes cracks in footings and concrete slabs.

Steel lintels support brick as information technology passes over windows and doors. Steel that is too small for the span tin can deflect, causing cracks in the masonry to a higher place. In addition to sizing lintels correctly, it's important that they deport on the brick at each side of the opening and non be fastened to the woods framing behind. Wood expands and contracts more masonry. Fastening the lintel to the framing can cause cracks in the bricks.

Rusting lintels besides can damage bricks. Steel expands as it rusts, lifting the masonry. The stair-shaped cracks that run up and away from the acme corners of door and win dow openings are usually caused past this rust. The all-time way to avoid them is, one time once more, to manage the water. Lintels should be flashed carefully to keep them dry and to shed any water that gets behind the brick veneer.

Cracks are also caused by poor workman ship. Over the long haul, joints that are packed solid with mortar perform a lot bet ter when exposed to the elements than joints that accept voids under the surface. Although builders should take the steps described here to minimize movement in masonry struc tures, movement can't exist eliminated com pletely. At least some movement is inevitable, and then repairs volition get necessary somewhen.

Sizing upwardly the job

When people call me to repair brickwork, my get-go task is to look closely at the expanse in question and decide whether the work is going to exist cost-effective or even feasible. In general, I encounter three types of issues. The first is old mortar that's loose in spots and has some visible fissures and voids. In these cases, all that's needed is to grind out the mortar and repoint the joints.

The 2d type of trouble occurs when the brickwork has moved and created cracks, some of which run through the bricks. In this case, the homeowner has to make a dif ficult decision. The just mode to ensure that the brickwork won't crack again is to address the cause of the movement. Since this often involves replacing a lintel, or fifty-fifty repairing a footing, addressing the root cause can be very expensive. On the other hand, it may exist reasonable to presume that a firm that has been sitting in the same spot for 50 or more years has done all the settling it's going to do. Managing the water effectually the foundation may be enough to stop any further progress of the underlying cause, and but repairing the masonry becomes acceptable. I've made many repairs in such cases that accept held up well for over a decade.

The tertiary blazon of problem is when the masonry is falling autonomously and can't be repaired. A common example is brick stairs that were built without a concrete footing. No corporeality of repointing tin repair these aging structures, and I advise the homeowners that the best solution is to tear the whole matter out, dig and cascade a proper footing, and build a new set up of stairs. Brickwork on houses themselves rarely reaches this country because it's unremarkably repaired before then.

I frequently encounter poorly done repairs. The mortar is ofttimes the wrong type and the wrong color. It'due south smeared on the face of the bricks and finished in a manner that doesn't come close to matching the joints on the rest of house. Cracks that run through bricks are simply filled with greyness mortar. The repaired cracks might keep water out, but they are an eyesore. I ofttimes end upward redoing these botched fixes as I work my fashion around the house repairing other cracks.

U se the correct mortar

Mortar should be softer than the bricks and then that small stresses are captivated by the mor tar rather than dissentious the bricks. Before the tardily 19th century, mortar was very soft, consisting of lime and sand, and worked well with the soft bricks of the fourth dimension. Beginning in the late 19th century, improved kilns and manufacturing techniques created harder bricks, and portland cement became com monly available. Modernistic mortar e'er contains portland cement and sand, which sets upwardly harder than straight lime mortars. To improve workability and soften the mortar, masons add hydrated lime to the portland cement. In the 1920s, masonry cement came on the marketplace. Masonry cement contains portland cement just uses proprietary ingre dients in identify of site-added lime.

Varying the ratio of portland cement and lime (or the proprietary ingredients in masonry cement) to the sand yields dissimilar classifications of mortar with unlike com pressive strengths. Both portland-cement/ lime mortar and masonry-cement mortar are classified in three types: Yard, South, and N, with Blazon Chiliad being the hardest and Type N the softest. An even softer mortar, Type O, is non bachelor equally a masonry-cement mortar and can be made only past mixing portland cement and lime. To repair cracks in brick walls, Type Northward is considered ideal for most buildings built after 1900. For historic buildings with soft bricks, Type O or lime mortar without portland cement is usually specified.

Type K, Type South, and straight portland-cement mortar with no lime shouldn't be used to repair cracks in brick walls. They are hard and inflexible, adhering to the bricks so tenaciously that the slightest motility tin can cause the bricks to split and spall.

Clean out the old mortar

The first pace in repairing a crevice is to grind out the old mortar. Joints should exist basis to a depth that's twice their width (usually three⁄iv in. to 1 in.). The tools I employ depend on the hardness of the mortar and the bricks every bit well as the overall integrity of the wall. Old bricks can exist fragile, and I piece of work according to the maxim "First, do no harm." Mortar never comes out consistently. In the class of grinding and chiseling, the mortar farther back in the joint oft breaks and crumbles. That'southward non a problem; I merely fill the deeper space with mortar during the next stage of the task, actually getting a better repair in those areas.

Use a rotary hammer on vertical joints. With a generally sound wall, setting the tool in hammer-only mode and using a chisel bit makes quick work of mortar. If the wall is fragile, the chisel may be too aggressive. Instead, perforate the joint with a ane⁄iv-in. drill fleck and the tool set in hammer-drill way.	A constrict-betoken grinder makes quick work of horizontal joints. This 5-in. grinder uses a 1⁄4-in.-thick bract to grind out nearly of the mortar in one laissez passer. Its dust port attaches to a vacuum, which collects most of the grit. The grinder isn't for working on vertical joints considering information technology would cutting into the bricks higher up and below.
Clean the drilled joints with a common cold chisel. Don't chisel direct in or you'll risk loosening the bricks. Rather than pounding the chisel, just tap it and accept out a picayune mortar at a fourth dimension to avoid dissentious the wall.	Vacuum out the loose material. The new mortar won't stick well to loose crumbs. Use a crevice vac attachment to reach deep into the joints.

dampening the area of the broken bricks — **Dampen the area to be patched.** Extremely dry out masonry surfaces suck the moisture out of the mortar, preventing a proper cure. Spray the surface and then that it'southward good and moisture but not then that you inject a big amount of h2o behind the brick veneer. Let the surface dry so that the joints are still damp inside just there's no water on the surface of the bricks.

Make the mud to match

A mutual mistake is mismatching the mortar color. Achieving a perfect match is hard; old mortar can brandish a range of shades, and sometimes information technology was dyed. Prior to the 1960s, portland-cement/lime mortars prevailed and tended to be light tan in color. Masonry- cement mortars have gained popularity since then and are mostly gray but also come in white, tan, and buff. You can get a good match by making samples using mixes from different manufacturers and letting them harden for a calendar week or so; mortar lightens every bit it dries. When standard materials don't friction match, I bring a
clamper of the mortar to Custom Match Colors (custom matchcorp.com), a local company with scores of powdered mortar dyes. If I get close to the existing color, so fourth dimension, dust, pollen, and algae brand pocket-size differences disappear.

Brand samples to friction match mortars. The writer sets five or half-dozen samples that come close to matching the mortar in front of the wall, so stands back to see which matches all-time.	Use Type N. Type Due north mortar can exist made by mixing one part Type North masonry cement with 21⁄four to iii parts sand; or by mixing one part portland cement, near i part hydrated lime, and the sand. Add dye according to the manufacturer's instructions.
Mix a dry mortar. Offset with a pocket-size amount of water, and mix to make a moist but crumbly mixture. Add more water gradually mixing until the material sticks together in a smooth glob.	Identify a 1⁄2-in.-thick layer of mortar on a militarist. Milkshake and tap the hawk to assistance the mortar stick and not slide off. Every bit it dries, mortar grabs the surface of the hawk. If the mortar is wet, spread it out so that it dries to a amend consistency.

Fill the joints

To transfer the mud from the hawk to the wall, I employ tuck pointers in several widths ( 1⁄4 in., 3⁄8 in., 1⁄2 in., v⁄8 in., and 3⁄iv in.), choosing the widest that will fit in the joint I'm filling. When possible, I piece of work directly from the hawk. Only sometimes there are obstructions such as sills, or it'due south too shut to the ground to hold the militarist, and so I transfer the mud on the tuck arrow. I utilize the mud in layers and allow each to set up a bit before applying the next. I go along until the joints are packed full.

For carrying the mortar to the joint, I utilize the tuck arrow to cut a 1⁄2 -in. strip of mortar on the hawk. I make a long movement of pulling the mortar along the surface of the hawk. This adheres the mortar to the tuck arrow so that I can carry information technology to the joint without dropping it. I keep a 4-in. brick trowel handy for patting down and shaping the mortar on the hawk; this helps keep the pancake of mortar together and at the right thickness.

carry the mortar with the tuck pointer upside down when repairing broken bricks — **ane** Carry the mortar with the tuck arrow upside downwardly.

rotate the tuck pointer into the joint of the broken bricks — 2 Rotate the tuck pointer into the joint.

pack the mortar in layers — 3 Pack the mortar in layers.

using a brick trowel for short vertical joints — **Different joints take different trowels.** While the constrict arrow'southward length is an advantage on horizontal joints, it can be a liability with the shorter vertical joints. A 4-in. brick trowel's shorter length is useful here.

working the mortar directly from the hawk to repair broken bricks — **Work direct from the hawk if yous can.** On long, straight runs, it's almost efficient to gear up the border of the hawk at the bottom of a horizontal joint and use the tuck pointer to push the mud straight into the joint.

Finish the joints

It's as important to friction match the contour of the repaired joints with those on the rest of firm as it is to lucifer the colour. Mortar joints tin can be finished in several ways. To start, later setting upwardly slightly, joints can merely be cut affluent with the face of the bricks and and so brushed with a soft castor to texture them and blend them into the edges of the bricks. They also tin can be raked back about one⁄four in. from the surface. The joint raker is a special tool for this that helps to maintain a consistent joint depth, only you also can rake out the joint with a constrict arrow.

Fill the joints to the brim. This packs the mortar in, helping to go along water out and to ensure that each brick is fully supported.	Rake out the excess. Many mortar joints are recessed from the confront of the brick. A joint raker holds a common nail at the desired rake depth and uses the nail head to scrape out extra mortar.
Tool the joint smooth. To friction match these existing joints, all that'due south needed afterwards raking is to smooth the mortar with a tuck arrow.	Clean upward. Afterward the final tooling, utilise a soft-bristle castor to remove whatever stray mortar.

Finishing options. A third style to finish joints is past using a jointing tool to shape the mortar. There are many different jointing tools that tin mold joints to a variety of profiles, including concave, Five-joint, weathered, beaded, and grapevine.

shape to match existing brick joints — **Shape equally needed.** Matching an existing joint profile is a affair of using the correct tool. In this case, a grapevine tool is called for.

Patching cracks in bricks

When a crack runs through a brick, many people think the solution is replacement. There are ii bug with that, the first being finding a replacement brick. Even if a brick with the same pattern were bachelor, the existing ones have weathered, and then a color match would be unlikely. The second problem is that removing an entire brick is invasive; peculiarly on an older wall, 1 brick can pb to another and and then to another. Instead, I fill cracked bricks with mortar dyed to match.

To brand staining the mortar joints less likely, I wait until the day afterward repairing the joints to make full whatsoever cracks in the
bricks. Information technology'south hard to get an exact color match. There are often several shades and colors of bricks in the same wall, and in many cases, individual bricks are mottled with different shades and colors. Even if I don't match the color of each brick perfectly, using a color that matches some bricks in the wall goes a long way toward making the crevice disappear and maintaining the bond pattern on the wall.