Brick is one of the most common exterior materials in the Atlanta metro, particularly in older neighborhoods like Decatur, Brookhaven, Druid Hills, and throughout DeKalb and Fulton counties. It's durable, low-maintenance relative to wood, and ages beautifully when properly maintained. But brick and mortar are not pressure-washing-proof, and the technique required to safely clean brick is fundamentally different from what's appropriate for concrete or vinyl siding.
Cleaning brick incorrectly — using too much pressure, the wrong nozzle angle, or inappropriate chemistry — can cause irreversible damage: eroded mortar joints, spalled brick faces, efflorescence development, and water infiltration pathways that compromise the wall assembly. This guide explains exactly what makes brick different, what cleaning approach is appropriate for different scenarios, and how to identify conditions that require expert assessment before any cleaning begins.
Why Brick Requires a Different Approach
The Mortar Joint Problem
The most critical vulnerability in any brick wall is the mortar joint, not the brick itself. Modern brick is extremely hard and durable. Mortar — the cementitious compound between bricks — is intentionally softer than the brick it binds. This is by design: mortar is meant to be the sacrificial element that takes movement stress and weathering, rather than the brick. Mortar can be replaced (tuckpointing); brick faces cannot easily be repaired once damaged.
But that softness means mortar is highly vulnerable to high-pressure water. A pressure washer operating at 2,500–3,500 PSI directed at mortar joints at close range can erode years of mortar in a single pass. The most dangerous angles are perpendicular to the joint face (direct hit) or at a steep raking angle across joints. Once mortar is eroded, the wall is compromised: water enters the joint, moves into the wall cavity, and can cause interior water damage, efflorescence, and accelerated freeze-thaw spalling.
Old vs. New Mortar
Pre-1950 brick construction in Atlanta typically used lime-based mortar rather than modern Portland cement mortar. Lime mortar is softer, more flexible, and more permeable by design. It was also specifically matched to the softness of older, more porous brick. If lime mortar is replaced with Portland cement during tuckpointing, the harder modern mortar transfers stress to the softer historic brick and causes spalling. The cleaning implication: any home built before 1960 with original mortar should be assumed to have lime mortar and treated accordingly — which means absolute minimum pressure and chemical-first cleaning approach.
Brick Porosity and Type
Not all brick is equally dense or hard. Standard modern modular brick is vitrified (fired at high temperature to near-zero porosity) and handles moderate pressure well. Older common brick, handmade brick, and some decorative face brick is more porous and more susceptible to water infiltration and surface spalling under high-pressure impact. Roman brick (thin horizontal profile common in 1960s–70s construction) is typically well-fired but has thinner individual faces. Any brick showing existing surface spalling (flaking off the face) should not be cleaned with direct pressure — the mechanical action of the water accelerates existing delamination.
The Right Approach: Soft Wash for Most Brick
For the vast majority of residential brick cleaning in Atlanta, soft washing is the correct method. This means applying a low-pressure chemical solution (sodium hypochlorite with a surfactant, properly diluted for masonry) that kills and dissolves biological growth — algae, mold, lichen — then rinsing with low-pressure water to clear the residue.
Why Chemical First Works Better
Algae and mold on brick are not just sitting on the surface — they're actually growing into the pore structure of the masonry. Blasting them with high pressure removes the visible portion but leaves the root structure (hyphae for mold, holdfast structures for algae) embedded in the brick and mortar. They regrow from that root structure within weeks to months. A chemical treatment that kills the organism at the root, followed by a rinse, removes the entire colony and provides significantly longer-lasting results.
For cleaning brick, we use sodium hypochlorite at 1–3% concentration (lower concentrations than roof work, appropriate for masonry), with a surfactant to improve penetration into the brick pores, applied at under 500 PSI. Results are typically excellent and last 18–24 months. Our house washing service uses this approach for all brick surfaces.
When Higher Pressure Is Appropriate
There are specific brick cleaning scenarios where moderate pressure (800–1,500 PSI) with appropriate technique is used:
- Mortar splatter removal from new construction: Mortar drips and splatter on brick after construction or masonry repair are best removed with controlled pressure and masonry cleaning acid (muriatic acid or phosphoric acid based). Chemical first to dissolve the calcium compounds, then pressure to rinse.
- Carbon staining on chimney brick: Carbon and creosote deposits on exterior chimney brick from flue backdraft can be addressed with moderate pressure and specialized chimney cleaning chemistry.
- Graffiti on brick: Graffiti removal on brick requires chemical gel removers and controlled pressure. High pressure alone drives paint deeper into porous brick; chemistry is essential. See our graffiti removal service.
- Modern brick in good mortar condition: For recently constructed brick with Portland cement mortar in good condition (no voids, no cracks, no spalling), moderate pressure directed with proper technique (holding pressure at 12–18 inches, moving parallel to mortar joints rather than into them) is acceptable.
Efflorescence: The White Mineral Deposit Problem
Efflorescence is the white, powdery or crystalline deposit that appears on brick and mortar surfaces when soluble salts migrate to the surface through water movement and then crystallize as the water evaporates. It's common in Atlanta after wet winters and heavy rain seasons. Efflorescence is not mold or algae — it's mineral salt.
What Causes It
Water enters the wall assembly — through failed caulk, deteriorated mortar joints, or just through the inherently permeable nature of masonry — picks up soluble salts from the concrete block backing, the mortar, or the soil, and carries them to the surface. When the water evaporates, the salts are left behind. Efflorescence often appears after a wet season, after irrigation systems that wet brick repeatedly, or after hydrostatic pressure from soil contact.
How to Treat Efflorescence
Fresh efflorescence (white and powdery, appearing recently) can often be removed by dry brushing followed by a dilute acid wash (white vinegar or dilute muriatic acid solution) and rinsing. Older, crystallized efflorescence that has hardened on the surface requires a stronger acid-based masonry cleaner. Pressure washing alone will not remove efflorescence — it will push it around and redeposit it. The underlying cause (water infiltration) must also be addressed or the efflorescence will return regardless of how thoroughly it's cleaned.
Painted Brick: Special Considerations
Many Atlanta-area brick homes — particularly in Decatur, Virginia-Highland, and Grant Park neighborhoods — have painted brick. Painted brick presents unique challenges for cleaning:
Pressure and Paint Adhesion
Paint on brick is bonded to a porous, textured substrate. The bond is only as strong as the bond between the paint and the brick face. High-pressure washing on painted brick can lift loose paint, force water under paint blisters, and accelerate existing adhesion failures. If the paint is already peeling or chalking, pressure washing will make it worse and may require spot-repainting after cleaning. This is not the contractor's fault — it's the natural result of cleaning aging paint — but it should be communicated honestly before the job begins.
Low-Pressure Approach for Painted Brick
The correct method for painted brick is soft washing with appropriate chemistry (lower concentration than bare masonry, pH-balanced to avoid accelerating paint breakdown) followed by a rinse that's low enough in pressure to clean without mechanical lifting of paint. If you know your painted brick needs repainting in the near future, professional cleaning is still worthwhile as a prep step — clean, deglossed surface improves paint adhesion significantly versus painting over dirty or algae-coated brick.
Pre-Cleaning Assessment: What We Look For
Before cleaning any brick surface, a qualified contractor should assess:
- Mortar condition — are there open joints, crumbling sections, or recently pointed areas that haven't fully cured?
- Brick condition — any spalling, cracking, or existing delamination?
- Evidence of active water infiltration — staining patterns, efflorescence location, moss growth in joint corners?
- Paint condition on painted brick — adhesion testing by pressing and lifting tape on test areas
- Age and approximate mortar type for older homes
If a contractor arrives and immediately begins cleaning without any surface assessment, that's a red flag. Proper brick cleaning starts with understanding what you're working with. We assess every brick surface before beginning work and will tell you honestly if we see conditions that need repair before cleaning, or that will limit cleaning results.
We clean brick homes throughout Decatur, Atlanta, Brookhaven, Marietta, and the full metro area. Call (678) 748-3578 for a free assessment and honest quote for your brick home.