By Eric Moshier – Certified Heater Mason, Third-Generation Mason, MHA Technical Committee Member, ASTM E1602 Masonry Heater Group Member
Solid Rock Masonry LLC of Duluth, Minnesota provides brick restoration and repointing for buildings, walls, chimneys, and facades throughout northern Minnesota and northwestern Wisconsin, within about 90 minutes of Duluth. Owner Eric Moshier is a third-generation mason with more than 25 years and 800 completed projects. Brick failure in this climate is almost never a mystery and almost never a brick problem. It is a water problem, and very often it is a problem created by the last repair. Hard modern mortar on soft old brick destroys the brick. Sandblasting destroys the brick. Sealing and painting the face destroys the brick. We diagnose why the wall failed, fix that cause, match the brick and the mortar to what is already there, and repair the damage properly. This page explains how brick actually fails, what a proper brick restoration involves, and how to tell a real repair from a cosmetic one.
Brick does not fail. Water fails, and the brick pays for it
Brick is fired clay. A good brick has a hard, dense outer skin created in the kiln, and a softer, more porous interior. That fired skin is what makes brick last a hundred years in Duluth. Break the skin and the brick is finished.
Water is what breaks it. Brick absorbs water. In our climate that water freezes and expands by about nine percent, dozens of times each winter, inside a material that cannot move. Something has to give. If the mortar is soft, the mortar gives, and that is fine, because mortar is replaceable. If the mortar is harder than the brick, the brick gives, and that is not fine, because brick is not.
So the entire craft of brick restoration comes down to two questions.
Where is the water getting in? And what is the weakest thing in this wall?
Get those two right and the repair lasts fifty years. Get them wrong and you have accelerated the destruction of a building you were hired to save.
The single most destructive thing done to brick in America
Portland cement mortar on soft historic brick.
It is done every day, by well-meaning contractors, on beautiful buildings, and it is close to irreversible.
Here is the mechanism. Brick made before roughly 1930 was fired at lower temperatures in less consistent kilns. It is softer and considerably more porous than modern brick. It was laid in lime mortar, which is also soft and highly permeable. That is a matched system. Water that gets into the wall travels to the joints and evaporates out of the joints, because the joints are the path of least resistance. The mortar slowly erodes. Every sixty or eighty years, somebody repoints it. The brick is untouched.
Now point that same wall with modern Portland cement mortar. Portland is roughly ten times stronger than lime mortar and close to vapor-impermeable. You have just made the mortar the hardest, least permeable thing in the wall.
The water still gets in. It always gets in. But now it cannot get out through the joints, so it exits through the only path left, which is the face of the brick. It freezes there. And instead of a crumbling joint, the face of the brick spalls off, exposing the soft interior, which then absorbs water faster, and fails faster, and the wall unravels.
You can spot this from the sidewalk. On a wall that has been hard-pointed, the mortar joints stand proud of the brick, sharp and square, while the brick faces between them are pitted, hollowed, and crumbling. The mortar has outlived the brick. That building is being taken apart by its own repair.
Once brick spalls, it cannot be repaired. It can be replaced, or in some cases turned around if the back face is sound. That is it.
We match mortar to brick. On historic soft brick that means a lime-rich mortar, typically Type O or Type N, sometimes straight lime putty. We match it for compressive strength, for permeability, for color, for aggregate size and color, and for joint profile. On a modern hard-fired brick wall, a harder mortar is correct. The point is that it is a decision made deliberately after looking at the actual brick, not whatever was on the truck.
How brick walls actually fail
Water from above
This is the big one, and it is where we find the damage on nearly every brick building we look at.
Look at the top of a brick wall, a parapet, or a pilaster. If the cap, coping, or cornice is cracked, missing, poorly sloped, or has no drip edge, water is going straight down inside the wall. The wall then fails from the top down, and the worst damage will be concentrated in the upper few feet.
We assessed a brick church in Superior, Wisconsin where the damage was almost entirely at the tops of the brick pilasters, right below the concrete caps. Not at the base. Not in the middle. At the top. The caps were letting water in, it was running down inside the pilaster, and the brick was blowing apart from the inside out.
If we had simply replaced the damaged brick and left the caps alone, that repair would have failed within a few winters. That is a bandaid, and someone would have paid for it twice.
Failed previous repairs
On that same building you can see the ghosts of previous patch repairs: mismatched brick, hard grey mortar, patches that have themselves cracked and stained. Somebody was here before us and treated the symptom.
Old patch repairs are one of the most reliable diagnostic signs we have. When we see them we know two things. We know where the water problem is, because somebody already noticed it there. And we know the water problem was never fixed, because the patch failed.
Rust jacking on steel lintels
Above windows and doors there is usually a steel angle lintel carrying the brick. Steel rusts. Rust occupies up to ten times the volume of the steel it came from.
So a rusting lintel does not just weaken. It expands, and it lifts the brick sitting on it. You see horizontal cracks in the mortar joint directly above a window, brick that is pushed out of plane, and eventually the lintel end shearing the corner off the wall. This is structural, it is progressive, and painting over the rust does nothing because the water is coming from above and behind, not from the visible face.
The fix is to remove the brick, address the lintel, restore flashing over it, and rebuild. It is real work. There is no shortcut, and anyone offering one is selling you a few years.
Missing or blocked weeps and through-wall flashing
A cavity wall is designed to let water in and then get it back out. Water passes through the brick, runs down the back of it, lands on through-wall flashing, and exits through weep holes at the bottom.
If the weeps are missing, painted over, mortared shut, or clogged, that water has nowhere to go. It sits in the wall. In winter it freezes. Every year.
We see brick walls where the entire bottom course is destroyed and everything above it is fine. That is a drainage problem, not a brick problem, and repointing it will not fix anything.
Cracking – and telling settlement from shrinkage
Not all cracks mean the same thing, and reading them correctly is most of the diagnosis.
- Stair-step cracks through the mortar joints, widening toward one end, usually mean foundation movement or settlement. The masonry is telling you the ground under it moved. Repointing that crack without addressing the movement means the crack comes back.
- Vertical cracks near the corners of long walls are frequently thermal expansion with no expansion joint to accommodate it.
- Horizontal cracks directly above a window or door are usually rust jacking on the lintel.
- Horizontal cracks part way up a wall can indicate corroded wall ties or a wall that is bowing.
- Cracks straight through the brick units rather than around them mean the mortar is stronger than the brick, and we are back to the Portland cement problem.
We read the cracks before we quote. The crack is the building telling you what is wrong with it.
Efflorescence
The white powdery bloom on brick is salt, carried to the surface by water moving through the wall and left behind when the water evaporates. It is not itself very harmful. But it is proof that water is moving through your wall in volume, and that is worth knowing.
Scrubbing it off treats nothing. Find the water.
Bulging and bowing walls
A wall leaning or bulging out of plane usually means the wall ties that hold the brick face to the structure behind it have corroded away, or that the wall has been saturated for years. This is a structural condition and it needs a structural answer.
The things that destroy brick, sold as maintenance
These are done constantly, they all look like they are helping, and they all shorten the life of the wall.
- Sandblasting. It removes the hard fired skin of the brick permanently and exposes the soft porous interior. A sandblasted wall absorbs water like a sponge and starts spalling within a few years. It is the fastest way to destroy a historic brick building and it is irreversible. Do not let anyone do it.
- High-pressure washing. Same mechanism, slightly slower. Cleaning brick should use the lowest effective pressure and the gentlest effective method, always tested on an inconspicuous area first.
- Painting brick. It seals the face. Water still enters from the top, the back, and the joints, and now it cannot evaporate out. It freezes behind the paint film and blows the face off the brick. Painted brick fails from underneath, and stripping the paint later often takes the brick face with it.
- Film-forming sealers. Same problem as paint. A wall must be able to dry.
- Caulking cracks. Hides the symptom, treats nothing, and the crack keeps moving.
- Grinding joints out with an angle grinder, carelessly. Fast and cheap and it permanently cuts the edges of the brick. Those saw marks never go away.
- Repointing without fixing the water source. The most common bandaid of all. Beautiful new joints, same leak, same failure, five years later.
Brick chimney restoration in Duluth
In Duluth, chimneys are the number one brick restoration call we get, and it is not close. A chimney takes weather on all four sides and straight down from the top, with no roof over it and no siding to shed the water. When a chimney starts spalling, leaning, or dropping brick, the cause is almost always at the top.
The number one culprit is the cap. Either a cast concrete cap that has cracked, or worse, a thin mortar wash that an older mason troweled over the top years ago. A mortar wash is not a crown. It is an inch of mortar with no reinforcement and no overhang, and it cracks within a few winters. Once it cracks, water runs straight into the top of the chimney.
The second culprit is the flue tile. Clay flue tile expands and contracts every time the chimney heats and cools, so it needs a gap around it at the cap, sealed with a high-temperature sealant so it can move. When a mason mortars the tile in solid instead, the tile cracks that mortar the first heating season, and from then on water pours down the gap between the tile and the brick. That water saturates the chimney from the inside, and our freeze-thaw winters break it apart from within, where nobody can see it until the brick is already ruined.
By the time the damage shows on the outside, the courses above the roofline are often gone. On one recent Duluth job, a bad cap had destroyed the brick across the entire top half of the chimney above the roof. We took it down to the roofline and rebuilt the top half in matched brick, with a proper crown and a rain cap so it would not happen again.
A chimney done right gets a cast concrete crown with an overhang and a drip edge, and a metal crown over that. When we are not pouring a new concrete cap, we always install a new metal crown. The flue tile is set with an expansion gap and the correct sealant, never mortared solid, and the whole chimney gets a rain cap. Fix the cap and the flue, and the brick below them stops failing.
How we do a brick restoration
1. Diagnose
We look at the whole building, not just the damaged spot. Caps, coping, parapets, flashing, lintels, weeps, gutters, downspouts, grade, and where the damage actually is. The location of the damage tells us where the water is. Damage at the top means water from above. Damage at the base means drainage or splash-back or rising damp. Damage above windows means lintels.
2. Identify the brick and the mortar
We measure. Modular brick runs 8 inches long nominal and 2 and 2/3 inches tall per course, but plenty of older buildings are not modular, and we are not going to guess from a photograph. We count the courses and measure them on the wall.
Then we match. On the Superior church assessment we pulled samples against the existing brick and worked through a range of brick blends to find the right match. Getting a match on a weathered hundred-year-old wall is not a matter of picking red. Colour, texture, size, the flash and the range within the blend, all of it matters, and it is the difference between a repair you cannot see and a permanent visible scar on the building.
For repointing, we follow the National Park Service standard, Preservation Brief 2, Repointing Mortar Joints in Historic Masonry Buildings, the same reference we cite in our brick restoration estimates. It calls for mortar matched to the original in strength, permeability, and appearance, and kept softer than the brick so the joints stay the sacrificial part of the wall.
We do the same for the mortar: strength, permeability, colour, and aggregate.
3. Fix the cause
Caps, coping, flashing, lintels, weeps, drainage. Whatever is letting the water in gets fixed first. There is no point in rebuilding a pilaster under a cap that is still going to leak.
4. Repair the damage
Damaged brick is cut out and replaced with matched brick. Joints are cut to a depth of at least two and a half times the joint width, squared at the back, dampened, packed in lifts, and tooled to match the original profile. The profile is not decoration. It is what sheds water off the joint.
5. Clean, if it needs it, gently
The gentlest effective method. Tested first. Never sandblasting.
Historic and institutional brick work
Our brick restoration work runs to churches, community buildings, commercial facades, and old houses. These are the buildings where the mortar-hardness question matters most, because they are the buildings most likely to be soft historic brick, and they are the buildings most likely to have been damaged already by somebody who did not know that.
If your building has been hard-pointed, we will tell you. We cannot undo it everywhere, but we can stop it getting worse, and we can make sure the next sixty years of repairs are done right.
See more of our restoration work.
The work we are proudest of
Brick restoration is not only chimneys and house walls. Some of the best work we have done is on structures that belong to everybody.
We have restored a historic stone arch bridge: falsework and centering built under the arch, the arch ring taken down and rebuilt stone by stone, and the whole thing put back the way the original masons left it. An arch is held up by nothing but compression and the accuracy of the stones. There is no glue, no steel, and no second chance. You either cut them right or the arch does not stand.
We have restored historic brick and stone buildings in Duluth, including grand Victorian houses where the brick and the brownstone had been weathering for over a century. We restored the stone pillars and patio at Chik-Wauk. We have rebuilt stone retaining walls on the Lake Superior shore, where the water and the ice do things to masonry that no inland wall ever has to survive.
That work is the reason we talk the way we do about mortar and water. When you have taken a two-hundred-year-old arch apart and put it back together, you understand exactly how much the last repair matters, and exactly what a careless one costs.
What it costs
Brick restoration scope ranges enormously, from repointing a section of wall to rebuilding a parapet, so the number ranges with it. Every brick restoration we quote comes with a written estimate that lays out what we are doing and why each item is there.
Our pricing is competitive because we do a lot of this work and we are efficient at it. If a line on the estimate does not make sense to you, ask. We will explain what it is for.
Frequently asked questions
How do I know if my brick needs restoration?
Look for: brick faces flaking or popping off, mortar joints recessed more than about a quarter inch or crumbling to sand, white staining, cracks, brick pushed out of plane, mortar joints standing proud of the brick, or pieces of brick and mortar on the ground. Any of those is worth a look, and usually the start of a real brick restoration rather than a quick patch.
Why is my brick crumbling but the mortar looks fine?
That is the classic signature of hard Portland cement mortar on soft brick. The mortar is stronger than the brick, so the brick has become the sacrificial element. It is the wrong way round, and it is why your brick is being destroyed.
Can spalled brick be repaired?
No. Once the fired skin is gone, the brick is finished. It can be replaced, or sometimes turned if the back is sound. Anyone offering to patch the face of a spalled brick with mortar is selling you a repair that will fall off.
Should I seal or paint my brick?
No. Both trap water inside the wall and accelerate failure. A brick wall has to be able to dry. There are breathable, vapor-permeable repellents that are appropriate in some situations, but they are never a substitute for fixing the water source.
Can you match my brick?
Usually, yes. We measure the existing coursing and work through sample ranges to match colour, texture, size, and blend. On a weathered wall a perfect match is not always possible, but a close one usually is, and getting it right is the difference between an invisible repair and a permanent scar.
What is tuckpointing?
In common usage it means replacing deteriorated mortar joints. What matters is not the word but whether the joints are cut to proper depth, squared, and filled with mortar matched to the brick. A “tuckpointing” job done with the wrong mortar does more harm than doing nothing.
Do you work on churches and commercial buildings?
Yes. Churches, community buildings, commercial facades, and historic homes. Institutional brick is where the mortar-hardness question matters most, and where a wrong repair does permanent damage.
How far do you travel?
Brick and stone restoration within roughly 90 minutes of Duluth. Masonry heater work is nationwide.
Talk to a third-generation mason
If your brick is spalling, cracking, staining, or losing mortar, let us look at it before someone patches it. A proper brick restoration starts with finding out why the wall failed, not just filling the joint.
We will tell you where the water is coming from, whether the last repair helped or hurt, and what actually needs to be done. Sometimes that is less than you feared. Sometimes it is more. Either way you will know why.
Solid Rock Masonry LLC
5347 Howard Gnesen Road, Duluth, MN 55803
218-343-2978
eric@solidrockmasonry.com