Is Masonry Waterproofing Worth It? Brick Sealing in Chicagoland

It's one of the most common questions we get from Chicago-area homeowners: "Is masonry waterproofing actually worth it, or is it just an upsell?" It's a fair question — and the honest answer is it depends entirely on how it's done. Done right, brick sealing is one of the smartest, lowest-cost things you can do to protect a brick home in our climate. Done wrong — the wrong product, or sealing over failing mortar — it doesn't just waste money, it can actively trap water and accelerate spalling.

This guide cuts through the confusion: what masonry waterproofing really is, when it's worth it, when it isn't, and why the order of operations matters more than the sealer itself. Paul Lally's Masonry has been waterproofing Chicagoland brick since 1988, and we'll only recommend it when it'll genuinely protect your home.

What masonry waterproofing actually is

Masonry waterproofing means treating brick and mortar to reduce how much liquid water they absorb. Brick is naturally porous — it drinks in rain and snowmelt like a sponge — and in a climate like ours, that absorbed water is the root of most masonry damage. Waterproofing aims to keep that water out while letting the wall stay healthy.

But here's the key distinction most homeowners never hear: not all sealers work the same way, and the difference is everything.

Breathable penetrating sealers (the right approach)

A breathable penetrating sealer — typically a silane/siloxane chemistry — soaks into the brick and lines the pores. It repels liquid water while still allowing water vapor to pass through and escape. The wall sheds rain but can still "breathe out" any moisture inside it. This is what we use.

Film-forming sealers and paint (the wrong approach)

A film-forming sealer — and especially paint — lays a coating on the surface that blocks not just liquid water but also vapor. On paper that sounds more protective. In reality it's a trap: any moisture already in the wall (and in an old masonry wall, there's always some) can no longer escape. In Chicago's freeze-thaw climate, that trapped water freezes, expands, and spalls the brick from the inside out. We've been called to repair plenty of walls ruined by a well-intentioned coat of the wrong sealer or paint.

Sealer type	Repels liquid water	Lets wall breathe	Verdict in Chicago
Breathable penetrating (silane/siloxane)	Yes	Yes	Recommended
Film-forming surface coating	Yes	No	Risky — traps moisture
Paint on brick	Partly	No	Avoid — traps moisture, can't be undone

The building science: why water is the enemy

To understand why waterproofing matters, you have to understand freeze-thaw. Brick absorbs water. When temperatures drop below freezing — which happens dozens of times each Chicago winter — that water turns to ice and expands roughly 9%. The expansion pushes against the inside of the brick. When it thaws, the water recedes; the next freeze pushes again. Cycle after cycle, year after year, this mechanical stress flakes and crumbles the brick face — the damage we call spalling.

Reduce the water the brick absorbs, and you reduce the fuel for freeze-thaw. That's the entire value proposition of waterproofing: less water in, less freeze-thaw damage out. But it only works if water can't simply bypass the sealed brick face by coming in through failing mortar joints — which is why sealing is never step one.

When you need it: the warning signs

Waterproofing is most worthwhile when you're seeing the early signals of water intrusion:

• Efflorescence — the white, powdery salt deposit on the brick face, a tell-tale sign water is moving through the masonry.
• Damp or stained interior walls behind exterior brick.
• A history of spalling — flaking or crumbling brick faces, especially on weather-exposed elevations.
• Highly exposed walls — south- and west-facing elevations and parapets that take the brunt of wind-driven rain.
• Porous or older brick — century-old brick on bungalows and greystones often absorbs far more water than modern brick.

If you're seeing these, waterproofing can be a high-value protection — after the underlying issues are addressed.

The right order of operations (this is the part that matters)

Here's the single most important thing in this entire article: waterproofing is the last step, not the first. Sealing a wall that's still letting water in through bad joints just locks that water inside. The correct sequence is:

1. Fix the water sources. Gutters, downspouts, grading, flashing, caulking around windows — stop the obvious water before anything else.
2. Tuckpoint and repair the masonry. Grind out and repoint failing mortar joints, replace spalled brick, address any lintel or structural issues. Sound, watertight joints are the foundation of any waterproofing.
3. Then waterproof. Once the masonry is sound and dry, apply a breathable penetrating sealer to repel future water while letting the wall breathe.

Skip step two and you've wasted step three — or worse, trapped moisture in the wall.

How a professional waterproofing job is done

When the masonry is sound and it's time to seal, here's how Paul Lally's Masonry approaches it:

1. Assess and confirm readiness. We verify the mortar is sound, the brick is dry, and any repairs are cured.
2. Clean the surface. Dirt, efflorescence, and old failed coatings are cleaned off so the sealer can penetrate.
3. Protect surroundings. Windows, trim, plantings, and walkways are masked and protected.
4. Apply the breathable sealer. A silane/siloxane penetrating sealer is applied evenly, typically saturating the surface so it soaks into the pores rather than sitting on top.
5. Verify coverage. We check that the brick is repelling water and that no areas were missed, reapplying where porous brick demands it.

Materials and techniques

• Silane/siloxane penetrating sealers — the breathable chemistry we trust for Chicago brick.
• Correct application rate — porous brick needs enough product to fully line the pores; under-applying leaves gaps, over-coating risks a film.
• Proper surface prep — sealer bonds to clean, dry masonry; applying over dirt, efflorescence, or damp brick undermines it.
• Matched repairs first — sound mortar (commonly Type N for residential brick) and brick matching before sealing.

Paul Lally's Masonry is a family-owned, licensed and insured masonry contractor serving Chicago and the Chicagoland suburbs since 1988 — tuckpointing, brick repair and replacement, chimney repair and rebuilds, lintel replacement, masonry restoration, and waterproofing for residential and commercial properties. Built on Craftsmanship. Backed by Experience. Free on-site estimates — call (708) 448-8866.

What drives the cost

We don't publish prices — every wall is different — but the factors that move a waterproofing job up or down are easy to understand:

• Square footage of wall to be treated.
• Height and access — upper stories and parapets need scaffolding or a lift.
• Brick porosity — thirsty old brick needs more product.
• Surface prep — heavy cleaning or efflorescence removal adds labor.
• Repairs first — most of the real value (and cost) is usually in the tuckpointing and brick repair that should precede sealing.

The only accurate number is a free on-site estimate — call (708) 448-8866 and we'll assess your walls and tell you honestly whether sealing is worth it for your home.

DIY vs. hiring a pro

Big-box stores sell brick sealer, and a motivated homeowner can roll some on. The risks are in what's invisible:

• Choosing the wrong product — grab a film-forming sealer or paint and you've set up a freeze-thaw trap.
• Sealing over failing mortar — without the masonry experience to judge joint condition, it's easy to lock water in.
• Uneven application — porous brick needs the right saturation; missed or thin spots leave the wall vulnerable.

A pro brings the diagnosis — should this wall even be sealed, and is the masonry ready? — plus the right breathable product and the repairs that have to come first. That judgment is the real value.

Chicago and Chicagoland context

There may be no better place than greater Chicago to understand why waterproofing matters — and why it has to be done right. Our freeze-thaw cycle is relentless: temperatures cross the freezing point again and again all winter, and every crossing is another chance for absorbed water to expand inside the brick. Add lake-effect moisture keeping walls damp, and you have a climate engineered to find every weakness in masonry.

Our housing stock raises the stakes. The brick bungalows of the Bungalow Belt, the greystones of the older neighborhoods, and the two-flats across Cook, DuPage, Will, and Kane Counties were often built with porous, century-old brick that drinks water far more readily than modern units. Protecting that brick with the right breathable sealer — after the mortar is sound — extends its life. Smothering it with paint or a film-forming coating does the opposite. We've seen both outcomes across the suburbs, from Palos Heights to Orland Park to Naperville.

Maintenance and prevention

Waterproofing is part of a larger water-management strategy, not a substitute for it:

• Keep gutters and downspouts clear and directing water away from the walls.
• Repoint failing mortar on schedule — joints are the first line of defense.
• Reapply breathable sealer when water stops beading, typically every few years on exposed walls.
• Inspect annually for efflorescence, spalling, and damp spots — early signs that water is finding a way in.
• Never paint your brick — it's the most common, most regretted masonry mistake in Chicago.

Related services

• Waterproofing & Sealing — breathable penetrating sealers applied to sound masonry.
• Tuckpointing & Repointing — the step that has to come first, closing the joints water uses to get in.
• Brick Repair & Replacement — for spalled or damaged brick before sealing.

The bottom line

So — is masonry waterproofing worth it? Yes, when it's done right: a breathable penetrating sealer on sound, freshly repointed masonry is real, cost-effective protection against Chicago's freeze-thaw cycle, and it can add years to your brick. No, when it's done wrong: the wrong film-forming sealer, paint, or sealing over failing mortar traps water and accelerates the very spalling you were trying to prevent. The product matters, but the order of operations matters more.

Paul Lally's Masonry has been protecting Chicagoland brick since 1988. We're family-owned, licensed, bonded and insured, and we'll tell you honestly whether your walls will benefit from sealing — and what needs to happen first. Built on Craftsmanship. Backed by Experience. Call (708) 448-8866 or request a free on-site estimate.