Pressure wash a brick house only at low pressure. The Brick Industry Association (BIA) says not to exceed 400 psi at the nozzle tip unless the brick manufacturer permits it, to use a 25 to 50 degree fan tip held at least 12 inches from the brick, and that anything above 800 psi “is not appropriate for brick and may damage the brickwork.” Water and a masonry detergent do most of the cleaning, not force: soak the wall, apply the cleaner gently, let it work, then rinse. Test a small hidden patch first and judge it only after it dries. Ventura County Roof Cleaning washes home exteriors across Ventura County, and this guide sets out what the brick industry and federal and state preservation standards actually publish, so you can tell a safe brick wash from one that strips the face off the brick.
Key Takeaways
- 400 psi at the nozzle tip is the brick industry’s rinse ceiling. Above 800 psi is high pressure, which BIA says is not appropriate for brick.
- Preservation standards start lower, at 100 psi or below, for older masonry.
- Most machines run far above these limits. GSA warns that “most commercial pressure washing systems operate at significantly higher pressures than those recommended.”
- Judge the test patch dry. Pressure damage “may not become apparent until after the wall has dried,” according to Washington, D.C.’s Historic Preservation Office.
What the Published Standards Say
Five organizations that publish masonry cleaning procedures agree on what a safe wash looks like and differ mainly in how cautious they are. The brick industry’s guidance is written for sound brickwork. The federal and state documents are written for historic and public buildings, so their numbers sit lower.
| Source | Written for | Rinse pressure | Nozzle and distance | Flow |
|---|---|---|---|---|
| Brick Industry Association, Technical Note 20 (2018) | New and existing brickwork | 100 to 400 psi; no higher than 400 psi unless the brick maker permits it | 25 to 50 degree fan tip, 12 inches minimum | 4 to 6 gallons per minute |
| U.S. General Services Administration | Historic federal masonry | Start at 100 psi or below, never above 400 psi | 45 degree fan tip, 18 inches minimum | About 4 gallons per minute |
| New York State Office of General Services, Section 040123 | State building masonry cleaning | 200 to 300 psi; 300 psi machine maximum | 25 to 50 degree fan | Not stated |
| National Park Service, Preservation Brief 1 | Historic masonry | Start at 100 psi or below, generally no higher than 300 to 400 psi | Not stated | Not stated |
| Washington, D.C. Historic Preservation Office | 19th century pressed brick | 200 to 600 psi usually sufficient; above 1,200 psi likely to scar or etch | Not stated | Not stated |
The pattern is consistent. Apart from BIA’s medium-pressure exception, which needs the brick maker’s permission, none of them goes above 600 psi for routine rinsing, and every one says to begin low and go higher only if the test patch needs it. The pressure rating on a washer tells you what the machine can do, not what the wall can take, which is why GSA adds that “use of a pressure regulator to reduce pressures may be needed.”
How the brick industry grades pressure
BIA defines four pressure classes, all at 4 to 6 gallons per minute, and says pressure “should be measured at the tip of the nozzle.”
| Class | Pressure at the tip | What BIA says it is for |
|---|---|---|
| Very low | Under 100 psi | Pre-wetting the wall |
| Low | 100 to 400 psi | Rinsing, the normal cleaning range |
| Medium | 400 to 800 psi | “May be appropriate in some cases, with certain types of brick,” only if the manufacturer permits |
| High | Over 800 psi | “Not appropriate for brick and may damage the brickwork” |
Flow does the carrying and pressure does the damage, so a wide fan with good volume is the safer way to rinse.
Inspect the Wall Before You Wet It
Brick cleaning is a condition decision before it is a pressure decision. Walk the wall at close range, in low raking light, and check five things.
- Spalling. Spalling is the flaking, crumbling or popping off of a brick’s outer face. The fired face is the brick’s protective skin, so a spalled brick is already failing, and a water jet speeds that failure instead of removing a stain.
- Mortar joints. Cracked, soft or missing mortar lets water straight into the wall, so repair first and wash later. BIA says “it is generally best to schedule cleaning at least seven days after brickwork is completed”; for recent repointing, ask the mason.
- Paint or sealer. Press tape on the coating and pull it off. If paint comes away, pressure washing turns a cleaning job into a stripping job. According to the U.S. Environmental Protection Agency, “If your home was built before 1978, it is more likely to have lead-based paint,” so have peeling paint on an older house tested before anyone washes it.
- Openings. Weep holes, vents, window seals, fixtures and outlets. Weep holes drain water out of a brick veneer wall, so never aim spray into them.
- Expectations. The New York State specification says that “at best, it is normally only possible to remove about 90 to 95 percent of the ‘dirt’ from a masonry surface without damaging it.” If a wall only looks new after more pressure, the last few percent is coming off the brick.
How to Wash a Brick Wall, Step by Step
- Test first. BIA calls for a trial cleaning on a 20 square foot sample area, judged after the wall dries. GSA’s historic masonry test patches are usually under 6 by 6 inches. Either way, pick a hidden section.
- Protect around the wall. Pre-wet and cover plants, close windows, cover outlets, and decide where the water will run.
- Saturate the wall. BIA says to pre-wet at very low pressure, under 100 psi, to saturate the area and the brickwork below it, and to “keep wet until final rinse.”
- Apply the cleaner gently, bottom up. BIA applies cleaning solution by brush or pump sprayer at no more than 30 to 50 psi. GSA says “high-pressure spray equipment shall not be used for the application of any cleaning product” and that cleaning runs “from the bottom of the wall toward the top.” Use a product labeled for masonry and follow its instructions. We do not publish mixing ratios.
- Agitate with a soft brush. The National Park Service recommends natural or synthetic bristle brushes, “never metal which can abrade the surface and leave metal particles that can stain the masonry.”
- Rinse top down at low pressure. GSA rinses “from top to bottom” with a wide fan tip. Keep the fan moving across the face of the brick, not into the joints, and keep the tip at least 12 inches away.
- Let it dry, then inspect before you move on to the next section.
Skip the acid. D.C.’s preservation office notes that acidic cleaners on acid-sensitive masonry, such as glazed brick, “will dissolve the surface,” and says they “may be appropriate in low concentrations on granite or unglazed brick,” while GSA’s procedure says “raw acids and/or alkalis may not be used for masonry cleaning.” Whether a wall can take an acid cleaner is a call for a masonry professional, not a hardware store label. Surface cleaners and other flat-work attachments belong on driveways, not on vertical brick.
Reading the Wall After It Dries
Wet brick hides texture loss and color change, so read the wall only once it has dried.
| What you see | What it usually means | What to do |
|---|---|---|
| Fuzzy, sandy or lighter streaks that follow the wand | The fired face was etched by too much pressure or too little distance | Stop. More washing will not put the face back |
| Mortar washed out of joints | Spray aimed into the joints, or mortar that was already weak | Mark and photograph it, and repoint before any more cleaning |
| White, powdery bloom | Efflorescence | Let the wall dry fully and find where the water is coming from |
| Streaks or tiger stripes | The cleaning solution dried, or the rinse was uneven | Work smaller sections, keep the wall wet, rinse sooner |
| Green or black growth that survived | Biological growth that needs dwell time, not force | Re-treat and let the product dwell as labeled |
Efflorescence is a white, powdery deposit of water-soluble salts that water carries out of brick or mortar and leaves on the surface as it evaporates. It is a moisture symptom rather than dirt, so a second hard wash adds water and is the wrong fix. Our stone and paver patio guide explains how to tell it apart from hard-water staining.
What Changes in Ventura County
Most published brick guidance is written for places that freeze. D.C. advises against pressure washing masonry between November and March, the National Park Service warns that a masonry wall “may take over a week to dry after cleaning,” and BIA prefers water cleaning only when the temperature “will be 40 °F or above and will remain so until the wall is dry.” On the Ventura County coast that rarely limits anything, though a cold inland winter morning is still a reason to wait until midday.
The local risk is heat. BIA warns: “Do not allow cleaning solutions to dry on brickwork. Be aware that an increased risk of rapid drying exists in high temperatures.” On a hot or windy day, wash early, work in small shaded sections and keep the brick wet.
Wash water is the other local issue. The U.S. Environmental Protection Agency notes that runoff picks up pollutants “like trash, chemicals, oils, and dirt/sediment” and carries them to rivers, lakes and coastal waters, and BIA says to control runoff “in accordance with the requirements of the jurisdiction.” Our driveway washing guide covers how to keep wash water out of the storm drain.
Most homes here are stucco, which needs its own low-pressure approach (see our house washing guide), so brick usually appears as a chimney, a planter, a garden wall or a veneer wainscot set against stucco, wood trim and planting beds. Each of those neighbors needs protecting too.
When to Stop and Call a Professional
- Mortar is failing or brick is spalling. That wall needs a mason before it needs cleaning. Ventura County Roof Cleaning is a cleaning company, not a masonry contractor, and we will tell you when a wall should be repaired first.
- The paint is peeling on a house built before 1978. Have it tested before anyone washes it.
- The brick is historic. Follow the preservation standards above and have the method set on a test panel.
- The work is above the first story. Do not run a pressure washer from a ladder.
- Growth survives a careful test. The fix is chemistry and dwell time, not more pressure.
For the order to book roof, gutter, wall and driveway work in, see our exterior cleaning services guide, or read how our pressure washing services match the method to each surface.
Frequently Asked Questions
What PSI should I use to pressure wash a brick house?
The Brick Industry Association says to rinse at 100 to 400 psi measured at the nozzle tip, with a 25 to 50 degree fan tip held at least 12 inches away and 4 to 6 gallons per minute of flow. Pre-wet at under 100 psi. BIA calls anything above 800 psi high pressure that is not appropriate for brick. For older or historic brick, the National Park Service and GSA start at 100 psi or below.
Can pressure washing damage brick?
Yes. Too much pressure etches the fired face of the brick, washes out mortar and forces water into the wall. Washington, D.C.’s Historic Preservation Office says a pressure above 1,200 psi is likely to permanently scar or etch historic masonry, and that the damage may not show until the wall has dried.
What is the white powder on brick after washing?
It is usually efflorescence: water-soluble salts carried out of the brick or mortar by water and left on the surface as it evaporates. It is a moisture symptom, not dirt. Let the wall dry fully, look for where the water is coming from, and do not wash it again harder.
Should you pressure wash painted brick?
Only after a test. Press tape on the paint and pull it off; if paint lifts, pressure washing will strip it unevenly. If the house was built before 1978, the EPA says it is more likely to have lead-based paint, so have peeling paint tested before anyone washes it.
When is the best time to wash brick in Ventura County?
A mild, still day, early in the morning or on a shaded wall. The Brick Industry Association warns that cleaning solutions must not dry on brickwork and that hot weather raises that risk. Freezing is rarely an issue here, but BIA prefers water cleaning only when it will stay at 40 °F or above until the wall is dry.
Get Your Brick Cleaned Without the Guesswork
Ventura County Roof Cleaning washes home exteriors across Ventura County with the method matched to the material, not one setting for every wall. On a free estimate visit we look at the brick, the mortar and any coating, and tell you whether the wall should be washed, how, or whether it needs a mason first. Every property is assessed individually. Request a free estimate and we will take a look.