Brick looks like the toughest surface on the house. The face is tough. The mortar between the bricks is not, and on older homes the brick often is not either. Here is what each stain is, what a safe wash looks like, and when the job belongs to a mason.
Brick gets its strength from the kiln. Firing leaves a hard outer skin on each brick, and the inside is more porous than the face. Mortar is softer again, and that is on purpose. A wall is built so the mortar is the part that gives, cracks, and gets replaced, because repointing joints is far cheaper than replacing brick.
A pressure washer at full power works against all of that. It cuts the joints first, because they are the softest thing on the wall. It drives water deep into the masonry, which then has to dry out back through the face. And where the fired skin is thin or already cracked, it strips it, leaving a rough, pale patch that soaks up water and dirt faster than the brick around it.
None of that shows on the day. The wall looks clean and wet. It shows a year later as sandy joints, a white bloom of salts, or brick faces that start to flake after a winter of freezing and thawing.
A lot of the brick we see in Smithfield, Benson, and the older streets of Raleigh was laid long before modern brick standards. Older brick was often fired at lower temperatures, and it can be noticeably softer than what goes on a new house today. The mortar is often lime based, which is softer still and is meant to be.
Downtown storefronts are the extreme case. Many of those buildings carry a century of paint, patches, and repointing, sometimes with three different mortars in one wall. A wash that is fine on one section can erode the next. On those walls we test a small, out of the way area first, at the lowest pressure that does anything, and we look at the joints before and after.
Signs you are looking at soft, older masonry:
If you can scratch the mortar with a key, assume it will not survive a pressure washer.
Most calls about dirty brick are really about one of five things. They look alike from the street, and up close they are treated very differently.
| What you see | What it usually is | What it needs |
|---|---|---|
| White powder or crust, often low on the wall or under a window sill | Efflorescence: salts carried out of the masonry by water | Dry brushing, a light rinse, and finding where the water is coming from |
| Green or black film, worst on the north side and in shade | Algae and mildew | A soft wash that kills it, then a low pressure rinse |
| Orange or rust-red staining in the first two feet above the ground | Red clay splashed up by rain, which is iron | An iron stain remover suited to masonry, not more pressure |
| Brown or orange streaks under a light, a railing, or a gutter strap | Rust from metal hardware | A rust treatment on that spot, and fixing or coating the metal |
| Green or yellow-green stains on light colored, newer brick | Often vanadium salts from the clay itself | A specific cleaner. Strong acid can set this stain instead of removing it |
The wrong guess costs you. Acid on the wrong stain, bleach on iron, or a soaking on top of an efflorescence problem all leave the wall worse than it started. When we are not sure what a stain is, we test a spot before we treat the whole wall.
Efflorescence is the white bloom people most often want pressure washed off, and it is the one where pressure does the least good. Brick and mortar contain soluble salts. When water moves through the wall and evaporates at the surface, it leaves those salts behind as a white powder or crust.
So the real question is not how to get the white off. It is where the water is coming from. New brick blooms for a season or two as construction moisture works out, and that usually fades on its own. Bloom that keeps returning on an older wall points at something: a gutter overflowing onto the brick, a downspout dumping at the foundation, a sprinkler hitting the wall every morning, a failed chimney cap, or a window sill sending water into the joint below it.
If efflorescence keeps coming back in the same place, that part of the wall is wet more often than it should be. Washing will not fix it. A gutter, a sprinkler head, a sill, or a chimney cap usually will.
Brick siding gets the same approach as any other wall on the house. The cleaner does the work and the water only carries it away. Here is how the visit goes.
Before anything gets wet we walk the wall for soft, sandy, or missing mortar, flaking brick faces, and cracks. Anything already failing gets left alone or flagged to you, not washed harder.
Beds and shrubs get soaked first. Wetting the brick matters too, because dry, thirsty brick pulls cleaning solution deep into the face instead of letting it work on the surface.
A solution that kills algae and mildew goes on at roughly garden hose pressure, from the bottom up so it does not streak as it runs.
Dwell time does what pressure cannot. The growth dies in place and lets go of the texture of the brick. Rushing this step is how crews end up reaching for more pressure.
A low pressure rinse carries the solution and the dead growth off the wall, then the windows, the plants, and anything below get rinsed too.
Red clay at the base or rust under a fixture gets its own treatment on that spot. It is not a reason to turn the whole wall up.
Brick is textured, so it holds growth deeper than vinyl does, and a heavily stained north wall can need a second application. That is still a better answer than pressure, for the reasons laid out in soft washing versus pressure washing.
Painted brick is a paint job first and a brick wall second. The cleaning has to suit the paint, which means low pressure and a soft wash, the same as painted siding. A pressure washer will lift any paint that is already loose and plenty that is not, and it drives water behind the film, where it blisters later.
If the paint is peeling anyway, washing is the first step of a repaint, not a fix. On a house built before 1978, that paint may contain lead, and disturbing it has rules. Test it before anyone strips or blasts it. Our guide to washing before exterior painting covers the right order of work.
One more caution. Painted brick holds moisture more than bare brick does, so peeling in one area often means water is getting in behind it. Find that before the next coat goes on.
Brick on the ground is a different job from brick on the wall. Pavers and brick steps take foot traffic, hold water, and grow algae in the shade, which makes them slick. They can take more pressure than a wall, used through a flat surface cleaner rather than a wand held close.
The joints are what to watch. On sand-set pavers, the sand between the bricks is what locks them together, and any real cleaning washes some of it out. Plan to re-sand afterward, once the surface is dry, so the new sand settles all the way down. On mortared walks and steps, the joints get the same caution as on a wall. Soft or cracked mortar gets a gentler pass, and a loose brick on a step gets reported before somebody trips on it.
Front steps on older homes are often the most slippery surface on the property and the one older visitors use most, so they get our attention first. Paver patios, flagstone, and stamped concrete each have their own notes in cleaning a patio by surface.
A brick chimney is exposed on every side and takes rain from the top, so it is often the dirtiest brick on the house and the hardest to reach. The cleaning method is the same soft wash. What is different is what the staining tells you.
Dark streaks running down from the crown, white bloom on the chimney face or on an inside wall next to it, and mortar washing out of the upper courses are all signs that water is getting in. The usual causes are a cracked crown, a missing cap, or failed flashing where the chimney meets the roof. Those are jobs for a chimney professional or a mason. Washing makes the brick look better and does nothing for the leak.
We clean chimneys along with a roof wash or a full house wash. If we spot a crown or flashing problem while we are working, we tell you and show you what we saw.
A washer cleans brick. A mason repairs it. If you see any of these, call the mason first and wash after the repair has cured.
That last one matters on older homes. Mortar should be softer than the brick it holds. When a hard mortar is used to repoint soft brick, the brick becomes the weak point and starts to fail around the joints. A mason who works on older buildings will match the mortar to the brick. A pressure washer will only speed up whatever is already happening.
Washing before repointing is fine and often helpful, because the mason can see the joints clearly. Washing hard over failing joints is not. If you are unsure which you have, ask us to look at the wall before you book either one.
Most brick houses around here have a driveway, a front walk, and a porch slab, and they all drain onto each other. The right order is walls first and concrete and flatwork last, so nothing we clean above runs onto a slab we already finished. That is how we handle brick homes and brick storefronts across Raleigh, Clayton, Smithfield, Benson, and Garner.
Send us a photo of the wall and a close-up of one joint. That usually tells us whether we are looking at a wash, a stain treatment, or a call to a mason. Call (919) 698-3669.
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Low pressure and non-pressure roof cleaning are the same idea: the solution does the cleaning and the water only carries it away. Here is what that looks like on shingles, metal, and flat roofs, and how long it holds in central North Carolina.
Read the guide →ConcreteA driveway clean is more than a pressure washer and an afternoon. Here is what a proper concrete cleaning service does, stain by stain, and what no amount of cleaning will fix.
Read the guide →ConcreteA patio is not one surface. Broom-finish concrete, stamped concrete, pavers, flagstone, and brick all clean differently, and the method that suits one of them can ruin another.
Read the guide →We fly the roofline and show you the footage on the spot. You see your own gutters, joints, and downspouts on the screen instead of taking our word for it. It costs nothing and you are not committing to the cleaning.
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