Cleaning Brick and Mortar the Right Way
Brick itself is tough, but the mortar holding it together is often the softer, older material in the wall, and that difference should drive how a brick surface gets cleaned.
Why Old Mortar Is the Vulnerable Part
Brick is fired clay and holds up well to cleaning in most cases. Mortar is a different story. Mortar is a mix of sand, lime, and cement, and older mortar, especially anything original to a home built decades ago, tends to be softer than modern mortar mixes. Over years of weather, freeze-thaw cycles, and general aging, that mortar can develop small cracks, soft spots, or areas where it has started to erode.
The Memphis area does not see extreme winters, but it does see enough freeze-thaw swings in a typical winter for water that has worked into small mortar cracks to freeze, expand, and widen those cracks a little more each cycle. Combine that with high humidity for much of the year, which keeps brick and mortar damp longer after rain, and older mortar joints are often more fragile than they look from a few feet away.
That is the core issue with cleaning brick: the material most likely to get damaged by excess pressure is not the brick itself, it is the mortar between the bricks, and that damage is not always obvious until it has already happened.
Efflorescence: The White Haze on Brick
Efflorescence is the chalky white or grayish haze that shows up on brick and mortar, usually after moisture has moved through the material and evaporated, leaving mineral salts behind on the surface. It is common on brick that stays damp for extended periods, including brick near sprinkler overspray, foundation planting beds that hold moisture, or areas with poor drainage.
Efflorescence is a moisture issue more than a dirt issue. It can often be reduced with the right cleaning approach, but if the underlying moisture source (a sprinkler hitting the wall, a downspout draining against the foundation, poor grading) is not addressed, it tends to return. Cleaning it once without fixing the moisture source is treating the symptom, not the cause.
Paint Overspray and Other Staining
Brick and mortar also pick up paint overspray from painting projects on trim, shutters, or neighboring surfaces, along with general staining from dirt, mildew, and airborne grime that settles into the texture of both brick and mortar over time. Because brick has a porous surface, staining can sit slightly below the surface rather than just on top of it, which is part of why a simple rinse rarely gets brick looking fully clean.
The right cleaning approach depends on what is actually on the brick. General dirt, mildew, and algae respond well to a properly pressured wash. Paint overspray and deeper staining sometimes need more targeted attention, and in some cases will not fully disappear regardless of method if the staining has penetrated deeply into porous or already-damaged brick.
When Repointing Should Happen First
Repointing is the process of removing damaged mortar and replacing it with new mortar, and it is a separate trade from pressure washing. If mortar joints already show visible cracking, crumbling, or gaps, cleaning that brick before repointing can make the damage worse, since water and pressure can find their way into joints that are already compromised and erode them further.
A quick visual check before scheduling a cleaning is worthwhile: run a hand along a few mortar joints, particularly on older sections of a home or a wall that gets a lot of moisture exposure. If mortar crumbles or flakes off easily, or if there are visible gaps, that section likely needs repointing before it makes sense to clean it. We are not a repointing or masonry repair company, but we will point out visible mortar damage when we see it during a quote so it can be addressed by the right trade first.
Correct Pressure Makes the Difference
For brick and other masonry, our approach uses pressure paired with a surface cleaner attachment where appropriate, calibrated to the condition of the specific brick and mortar rather than a single fixed setting for every wall. Sound, well-maintained mortar can handle a properly calibrated wash without issue. Older or already-compromised mortar gets a more conservative approach, and in cases where the mortar is too far gone, we will say so rather than push ahead.
This is the same principle behind why we soft wash siding and roofs but use pressure with a surface cleaner on concrete: the goal is always matching the method to what the specific surface can actually handle, not applying maximum pressure everywhere and hoping for the best.
Questions
Can pressure washing damage brick or mortar?
Brick itself is generally durable, but older or already-cracked mortar can be damaged by excess pressure. The right approach calibrates pressure to the actual condition of the mortar, and any mortar that is already crumbling or cracked should be repointed before cleaning rather than after.
What causes the white chalky haze on brick?
That haze is called efflorescence, and it happens when moisture moves through brick or mortar and evaporates, leaving mineral salts on the surface. It is a moisture issue, and it tends to return if the moisture source, such as sprinkler overspray or poor drainage, is not addressed.
Should I clean brick before or after repointing damaged mortar?
Repointing should generally happen first if mortar joints are already cracked, crumbling, or gapped. Cleaning compromised mortar before it is repaired can force water and pressure into joints that are already weak and make the damage worse.