Cutting out failing joints, matching the original mortar strength to the brick, and packing new mortar in layers before tooling and curing it slowly forms the core of any successful repointing job. Most homeowners can repoint a single wall section or chimney in a weekend with the right mix, tools, and patience.
This walkthrough walks through the full repointing process, from spotting early damage and choosing the correct mortar to the actual cuts, packing, and curing work that gives an old wall another decade of life.
Diagnosing the Damage Before Picking Up a Trowel
Failing mortar announces itself the way a bad roof does: you only notice it once a chunk lands at your feet. Walk the wall corner to corner at eye level, then again from a step ladder, and flag every joint that is cracked, recessed, sandy, or missing pieces. Photograph the worst areas for before-and-after comparisons, because deteriorated joints remain a leading cause of water infiltration in brick walls, so what looks cosmetic is often structural.
Sound Test and Visual Cues
Tap each suspect joint with the handle of a screwdriver to separate sound mortar from spent mortar. Sound mortar rings like a dull bell; mortar that has lost its body thuds and powders under pressure. Surface crazing, those tiny spiderweb cracks living only in the outermost 2 mm of the joint face, can usually be patched with masonry caulk. Joints crumbling past 6 mm need full repointing because the damage has reached the mass of the bond.
Where Water Hits Hardest
Chimney caps, window sills, and lintels over doorways almost always fail first, because they catch the most rain and the most splash-back from the roofline. Damage concentrated there points to weather exposure rather than foundation movement, which matters when the mortar type is chosen next.
Repointing Versus Tuckpointing, and Which the Wall Actually Needs
Repointing replaces failing mortar with new mortar matched to the original joint, restoring structural integrity and weatherproofing. Tuckpointing lays a contrasting ridge line of putty down the center of a flush joint, a decorative technique reserved for historic and high-end brickwork where the face brick is meant to look larger than it is.
How to Tell the Two Apart on the Wall
If the existing joints are a single color and a single profile, repointing is the job. If the joints carry a fine raised line of white or grey putty running down the center of a different colored base, somebody has already tuckpointed that wall, and the technique should be matched. Most homeowners searching how to repoint brick want the structural repair, not the decorative overlay.
Putting decorative tuckpointing over a crumbling wall wastes effort. The cosmetic ridge will only last as long as the weak mortar underneath it.
When Tuckpointing Has a Place
On a 1920s bungalow where the joints are sound but the period look is worth restoring, tuckpointing over a fresh repointing base is the right move. On a 1990s subdivision home with sandy joints, it is decoration without a foundation.
That decision then dictates the mortar chemistry, since the wrong mix will undo either repair before the season turns.
Choosing the Right Mortar Mix for the Brick
New mortar must be slightly weaker than the masonry units, so any future stress cracks the joint instead of splitting the brick face. That single rule saves more brick walls than any other choice on this project, which is why matching the new mortar to the brick, not the bag on the shelf, lets the repair outlast the wall around it.
| Mortar Type | Best For | Compressive Strength | Key Trade-Off |
|---|---|---|---|
| Type N | Above-grade exterior walls, chimneys, most modern homes | ~750 psi | Balanced strength, workability, and vapor permeability |
| Type S | Foundations, retaining walls, severe-weather exposure | ~1,800 psi | Stronger but less breathable |
| Type O | Historic soft brick, interior or sheltered walls | ~350 psi | Very soft, must be used only on old, porous brick |
| Lime-based (ASTM C270 Type L) | Century-old lime-mortar construction | Varies | Flexible, self-healing, the right call for heritage walls |
The Most Expensive DIY Mistake in Masonry
Using modern Portland cement on century-old brickwork traps moisture inside the soft bricks and spalls their faces within a decade. If the house predates 1940, source a lime-based mix or a Type O blend, not a bag of general-purpose mortar from the big-box shelf. The wrong bag is the single most common reason DIY repointing fails within five years.
Color-Matching the New Joint
Sourcing sand from the same regional gradation as the original joint does more for color match than any pigment. Buy a small bucket of masonry sand from a local yard, screen out anything coarser than the original grains, then tint with iron-oxide powder until a dried test patty sits next to the wall without shouting. Premixed products save time, but they almost always need tinting on visible walls.
Getting the mix right in the bucket makes the rest of the job a matter of staging and pace rather than chemistry.
Tools, Safety Gear, and Materials Checklist
Stage every tool before a single joint is cut, because nothing derails a repointing job faster than climbing down a ladder to hunt for a jointer. Set up a stable workstation at ground level and one on the wall, and put the mixing station close to a hose.
Cutting and Removal Tools
- 4-inch angle grinder: paired with a diamond tuckpointing blade for long, straight runs of joint.
- Mortar rake or plug chisel: for detail work around fragile, historic, or chipped brick.
- Shop vacuum with HEPA filter: cuts airborne silica dust between sections.
Mixing and Application Tools
- Hawk and pointing trowel: the classic pair for pressing mortar into horizontal bed joints.
- Margin trowel: scoops mortar out of the bucket cleanly without dropping half of it on the ground.
- Grout bag: the right call for narrow or deep joints where a trowel feels clumsy.
- Jointers in matching profile: concave, V-joint, or struck, matched to the original wall.
Safety Gear Is Non-Negotiable
Angle grinder dust carries crystalline silica, which scars lungs permanently. ANSI-rated safety glasses, an N95 or P100 respirator, hearing protection, and cut-resistant gloves are the minimum kit. For work above 6 feet, set up stable scaffolding with a spotter. Ladder repointing on a chimney causes more weekend injuries than any other masonry task.
Materials Estimate
Budget roughly 0.5 cubic feet of premixed mortar or 60 lb of dry mix per 30 square feet of standard brick wall. Order 10 percent extra for waste, test batches, and the inevitable moment a joint swallows twice what was expected.
The Repointing Process From First Cut to Final Tooling
Cut first, then clean, then wet, then fill, then tool, because skipping any of those steps in order is the fastest way to produce a repair that fails within a season. The sequence matters because each step sets up the next one.
Cutting and Cleaning the Joints
Cut joints to a depth of about twice the joint width, typically 15 to 20 mm, without sawing into the brick faces. Let the blade follow the joint, not the brick, and use the mortar rake for the last 3 mm so an arris does not blow out. Brush out all dust and loose debris with a stiff wire brush, then a softer masonry brush, then a quick pass with the shop vacuum.
Dust left in the joint is the most common reason new mortar pops out within weeks.
Misting and Mixing
Mist the cleaned joints with water until the old brick darkens but no water beads on the surface, because dry brick will wick moisture out of the new mortar too fast and leave it powdery and unbonded. Mix the mortar to the consistency of wet peanut butter, let it slake for 10 minutes, then remix. Slaking wets every grain of cement evenly and yields a far more workable batch.
Filling in Layers
Load the grout bag or hawk and press mortar into the joint in layers rather than one deep fill. Pack the first layer about 10 mm deep, let it firm up to thumbprint stiffness, then add the next, because packing a 20 mm joint in a single lift traps air pockets that crack open as the mortar cures.
Tooling and Finishing the Profile
Strike the joint once it is thumbprint-firm with a jointer matched to the original profile. Common profiles include concave, flush, struck, raked, and V-joint, and each sheds water slightly differently. Keep the same shape as the rest of the wall, even if your taste prefers something else. Brush off excess crumbs with a soft masonry brush before the mortar sets hard.
Curing the Repair
Cure slowly over 3 to 7 days by misting several times daily and covering with plastic if the weather is hot, windy, or below 4 °C (40 °F). Repointing in freezing temperatures is a mistake, because the water in the mix freezes before the cement bonds and the joint fails the first time it thaws. Patience here pays for the next 30 years.
Even careful work can go sideways, which is when knowing the failure signs saves both wall and wallet.
Troubleshooting Common Failures and Deciding When to Call a Mason
Even careful DIY work hits a snag now and then, and a few common symptoms have very specific causes. Matching the symptom to the cause is faster than redoing the wall blind.
Mortar Cracking Within Weeks
Cracks that show up before the first month usually trace back to a curing problem. The joint dried too fast, or it was packed in a single deep lift instead of layered. Slow the cure with a plastic sheet and redo the affected sections in two or three layers rather than one.
White Salt Blooms on the Surface
Those white salt crystals blooming on the joint face, called efflorescence, signal moisture moving through the wall and carrying dissolved salts to the surface. Improve drainage above the joint, check for a missing chimney cap or drip edge, and switch to a more vapor-permeable mix for the next round. Sealing the surface makes it worse, because the moisture still has to go somewhere.
Brick Faces Spalling After Repair
Spalling brick after a repointing job almost always points to mortar that was too hard for the surrounding masonry. The fix is full removal and replacement with a weaker, lime-rich mix that lets the brick breathe, because the wrong mortar is now baked into the wall until it is dug out.
DIY Versus Hiring a Mason
DIY makes financial sense on a single wall section or chimney under 40 sq ft. Larger projects, load-bearing walls, or historic brickwork above one story are safer and often cheaper in the hands of a licensed mason. Specialists in masonry preservation typically quote $8 to $25 per square foot depending on access and brick age, while DIY averages $150 to $400 in materials per 100 sq ft.
Bottom Line
The repair lasts or fails based on three decisions: matching the new mortar to the brick, cutting joints to the right depth with the right blade, and curing slowly. Get those right, and the wall will outlast the next paint job, the next roof, and probably the next mortgage. Sample a small patch first, let it cure a week, and let the wall tell whether the choice was sound.
FAQ
What is the best mortar mix for repairing brick joints?
Type N mortar is the default choice for most above-grade exterior walls, while Type S suits foundations and severe-weather exposure, and Type O or lime-based mixes are reserved for historic soft brick. Match the new mix to the brick, not the shelf, so stress always cracks the joint rather than spalling the face.
Can you repair brick mortar yourself?
Yes, on a single wall section, chimney, or window surround under 40 sq ft. Larger projects, load-bearing walls, and historic brickwork above one story are safer and often cheaper in the hands of a licensed mason.
How do you remove old mortar from between bricks?
Cut joints to a depth of about twice the joint width using a 4-inch angle grinder with a diamond tuckpointing blade, finish the last few millimeters with a mortar rake or plug chisel to protect the brick arris, then brush out all dust with a stiff wire brush and a shop vacuum before wetting and filling.
How long does brick mortar repair last?
A properly executed repointing job using the right mortar type and a slow cure typically holds 25 to 30 years or more before it needs attention again, and it can extend the life of the surrounding brick wall by 30 years or more when caught before water infiltration spreads.
What tools are needed to repoint brick mortar?
The core kit is an angle grinder with a diamond tuckpointing blade, a mortar rake or plug chisel, hawk, pointing trowel, margin trowel, jointer, grout bag, wire brush, and misting bottle, plus ANSI-rated eye protection, an N95 or P100 respirator, hearing protection, and cut-resistant gloves.
When should damaged brick mortar be repaired?
Schedule the repair as soon as joints show recessed, sandy, or missing mortar, or any crack deeper than 6 mm, because deteriorated mortar joints are a leading cause of water infiltration in brick walls and the damage accelerates quickly once water gets behind the face.
