Most Brooklyn wall leaks come in through worn mortar joints, failed window caulking or the parapet above, not through the brick itself. MLM Construction Group waterproofs exterior walls across Brooklyn, licensed under HIC #2130570, with 97 Google reviews at 5.0. Call (516) 713-9199.
Brick buildings in Brooklyn take a lot of wind driven rain, especially on the side facing the weather and on the upper floors. Solid brick walls were built to absorb some water and dry it out again. The trouble starts when the balance tips and more water goes in than can come out.
In most cases the water is not coming through the brick. It comes through the mortar joints, which wear and crack over decades, through gaps around window frames where the sealant has dried out, and from the top of the wall, where a cracked parapet coping lets water straight down inside the masonry.
Inside: damp patches or bubbling plaster on an outside wall that come and go with the weather, peeling paint, a musty smell in a closet on an exterior wall, and staining at window heads after a storm.
Outside: white powder on the brick, which is salt left behind by water moving through the wall, mortar joints that are recessed, sandy or missing, cracked caulking around windows, and brick faces that have popped off, which is called spalling and is a sign of water freezing inside the brick.
Find the source first. If the parapet coping is open, nothing you do lower down will hold, so the top of the wall comes first. Then the joints: worn mortar is raked out and repointed with a mortar suited to the brick, which on older Brooklyn buildings is often softer than modern mix. Then the window perimeters get new backer rod and sealant.
Only after that does a water repellent go on, and it should be a penetrating, breathable product, usually silane or siloxane based, that soaks into the brick and makes the pores shed water while still letting water vapor out. On a sound wall with good joints, that is the step that tips the balance back.
The tempting fix is a thick coat of elastomeric paint or a glossy sealer over the whole wall. On masonry that usually makes things worse. Water still finds its way in at cracks and joints, but now it cannot get out through the face, so it stays in the wall, freezes in winter and pushes the face of the brick off. A lot of the spalled brick on Brooklyn facades is the result of a coating that trapped moisture.
There are walls where a coating system is the right answer, such as some stucco covered walls and certain exposed party walls, but it has to be a system chosen for that wall, not a paint applied to stop a leak.
Brooklyn has a specific version of this. When the building next door is demolished or was always lower, a party wall that was built to be inside becomes an outside wall. Those walls were never finished to face the weather, the brick is often softer, and the joints were never tooled. They leak, sometimes badly.
Exposed party walls usually need repointing and then a proper protective system, which can be stucco, a coating designed for masonry, or siding over a weather barrier, chosen based on the wall's condition. It is one of the most common reasons we are called to Brooklyn buildings in the fall.
Before the freeze, it is worth walking the outside of the building and looking at the parapet, the joints on the weather side, and the caulking at every window. Closing the obvious openings now stops water from freezing in the wall through the winter.
MLM Construction Group inspects exterior walls, finds the actual entry point, and gives you a written scope in the right order, starting with the source. Licensed under NYC DCWP HIC #2130570 and fully insured. See our waterproofing page or call (516) 713-9199.
Usually through worn or cracked mortar joints, failed caulking around windows, or an open parapet coping at the top of the wall. Water rarely comes through sound brick itself. Finding the actual entry point is the first step.
Not with elastomeric paint or a glossy film forming sealer. Those trap water in the wall, where it freezes and pushes the brick face off. A breathable penetrating water repellent, applied after the joints are repaired, is the right product for most brick.
It is a clear penetrating treatment that soaks into brick and masonry and makes the pores shed liquid water while still letting water vapor escape. It does not change the look of the wall and does not trap moisture.
In most cases yes. A repellent cannot bridge open or cracked joints, and that is where most of the water is getting in. Repointing first, then treating the wall, is the order that lasts.
Usually by repointing it and then adding a protective system suited to the wall, such as stucco, a masonry coating designed for the purpose, or siding over a weather barrier. These walls were never built to face the weather, so they need more than a sealer.
Yes. A cracked coping or open joints at the top of the wall let water straight down inside the masonry, and it can show up as damp several floors below. The parapet should be checked before anything lower down.
Yes. MLM Construction Group waterproofs exterior walls, party walls and parapets across Brooklyn, Queens and Manhattan, licensed under NYC DCWP HIC #2130570 and fully insured. Call (516) 713-9199 for a free inspection.