Why Is Water Coming Through My Brick Building?
A damp patch on an interior wall, paint bubbling near a window, or a musty smell in a finished basement can all trace back to one source: water working its way through the masonry. Brick buildings in Greater Boston have held up for generations, and many were built with rain in mind. Time and weather still take a toll, as mortar wears down, flashing corrodes, and small cracks open with each winter. Finding the entry point is the first step to fixing it, and JMS Masonry & Restoration provides masonry leak diagnosis and repair to property owners across the Greater Boston area.
TL;DR: Water usually gets through brick walls by way of worn mortar joints, failed flashing, cracked brick, or poorly sealed openings, and a professional masonry inspection can locate the source before interior damage spreads.
How Brick Walls Are Designed To Manage Water
Brick is naturally porous. During a storm, a masonry wall absorbs a certain amount of moisture and then releases it as the surface dries. Older mass masonry walls depend on their thickness to keep water from reaching the interior. Newer cavity walls use an air gap, flashing, and weep holes to collect water and send it back outside. The Brick Industry Association's technical notes explain these systems in detail for anyone who wants a deeper look. Leaks tend to appear when one part of the system stops doing its job.
Common Reasons Water Gets In Through Brick
Deteriorated Mortar Joints
Mortar is meant to be the softer, replaceable part of a wall. When joints erode, crack, or pull away from the brick, rain has an easy path inward. Our team addresses this through professional repointing, which removes failing mortar and replaces it with a compatible mix. The National Park Service offers helpful guidance on this process in Preservation Brief 2.
Failed Or Missing Flashing
Flashing is the metal or membrane barrier installed above windows, along rooflines, and around chimneys. Once it rusts through, tears, or was never installed properly, water can travel behind the brick and show up far from where it entered.
Cracked Or Spalling Brick
New England freeze-thaw cycles are hard on masonry. Water soaks into the brick, freezes, and expands, which can cause the face to flake off. Spalled brick absorbs even more water afterward, so damage tends to speed up once it starts.
Surface crazing, a network of fine hairline cracks, can also develop on glazed brick, stucco, and foundation parging. These cracks hold water against the surface, and winter freezing can widen them until moisture reaches the wall beneath.
Chimneys And Parapets
These features take weather from every direction. A cracked chimney crown, a missing cap, or open joints on a parapet wall can let a surprising volume of water into the structure below. Our chimney repair services cover crowns, caps, and rebuilds.
Gaps Around Windows, Doors, And Penetrations
Sealant around window frames, dryer vents, and air conditioning sleeves breaks down over the years. Small openings at these spots are among the most common leak sources we find on residential buildings in the area.
Warning Signs Inside And Outside
On the exterior, white chalky deposits called efflorescence suggest water is moving through the wall and carrying salts to the surface. Rust stains below steel lintels, loose bricks, and dark streaks that linger after rain are also worth noting. Inside, look for stained plaster, peeling paint on exterior walls, and damp corners in basements.
Ongoing moisture can support mold growth, and the EPA's mold resources outline why prompt attention matters.
A Word Of Caution About Clear Sealers
Clear waterproof coatings are often sold as a simple fix for leaky brick. On older buildings, they can trap moisture inside the wall, which may lead to more spalling over time. The National Park Service discusses the risks of water-repellent treatments on historic masonry in Preservation Brief 1. In most cases, repairing the underlying cause holds up better than coating the surface.
How Our Team Finds The Source of Water Intrusion
Every building is different, so our process begins with a close inspection of the exterior, including mortar, flashing, chimneys, and openings. We compare what we see outside with where the water appears inside, since the two locations often differ. From there, we recommend repairs that fit the building's age and construction. JMS Masonry offers masonry waterproofing and restoration in Boston, Newton, Quincy, Lynn, and surrounding communities, with particular care for historic masonry.
Contact JMS Masonry for Boston Brick Repair Before The Next Storm
Small leaks rarely stay small. Catching the problem early can help avoid costly interior repairs and structural damage later. JMS Masonry & Restoration provides brick repair and leak diagnosis throughout the Greater Boston area. Call our team at 781-435-0498 or request an estimate online to schedule an inspection.
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