Window and door perimeter sealing for Jersey City buildings

A leaking window rarely drips from the glass. Rain hits the frame, runs down its face and finds the gap where the frame meets brick, siding or stucco. From there it travels inside the wall and appears lower down: a soft patch of drywall under the sill, paint bubbling beside the casing, or a stain on the ceiling of the room below. On older brick rowhouses the gap often hides under a stone sill or behind a steel lintel, two places nobody looks until the plaster gives way.

The usual culprit is sealant at the end of its life. Caulk shrinks, hardens and pulls away from one side of the joint after years of summer sun and winter freeze-thaw. Sometimes the original bead was simply smeared over a wide gap with nothing behind it, so it tore the first winter. Wind-driven rain from a nor'easter then pushes water through that crack under pressure, which is why some windows stay dry all summer and only leak in one particular kind of storm.

Steel lintels deserve their own mention on brick buildings. The angle iron spanning the top of a masonry opening was often set with no flashing above it, so water that gets into the wall runs down onto the steel and sits there. Rust expands, lifts the brick above and opens the joints even further. Sealing at the lintel helps, but where the steel is badly rusted we'll tell you it needs repair before any new sealant goes on.

A sealant joint is not a fill. It's a flexible band that bonds to two sides and stretches as the frame and wall expand and contract with temperature. To do that it needs the right shape: roughly as wide as it is deep, stuck to the two sides only, and free to flex in the middle. Backer rod, a closed-cell foam cord pressed into the gap, sets that depth and keeps the sealant from bonding to the back of the joint, which would tear it the first time the building moves.

Before any new bead goes in, we cut out the old caulk completely. Laying fresh sealant over failed material just moves the failure line a few millimeters. We clean away dust and residue, prime where the surface calls for it, insert backer rod, then tool the bead so it presses firmly into both sides with a slight hourglass profile. On very wide joints at old masonry openings, we may build the gap down first so the sealant isn't asked to bridge more than it can handle.

Different joints need different chemistry. Silicone sealants hold up very well to sunlight and stay flexible for a long time, which makes them a strong choice on aluminum condo window walls and glass-to-metal joints. Polyurethane sealants grip masonry and wood well and can be painted, so they suit brick openings and painted trim on rowhouses and frame houses. Hybrid polymer sealants sit between the two and bond to mixed surfaces. Cheap acrylic caulk has its place indoors, but it doesn't belong on an exposed exterior perimeter.

We pick the sealant by what it has to stick to and how much the joint moves, and we check that it's compatible with any old material that can't be fully removed. Product choice matters less than most people expect. Surface prep and joint shape decide most of the outcome, and a well-shaped polyurethane joint will outlast a badly placed premium silicone almost every time. We'll explain which sealant we're using on your openings and why, without burying you in product sheets.

On waterfront condo and rental towers in Newport and around Exchange Place, perimeter leaks usually show at aluminum window walls where the factory sealant has weathered, or where one window unit butts into the next at a slab edge. Those jobs mean coordinating with property managers and boards and scheduling access through units. We photograph each opening we reseal, so the board has a clear record of which stacks are done and which are still waiting.

On downtown brick rowhouses, the weak spots are stone sills with open end joints, steel lintels that have rusted and pushed the brick, and the gap between wood frames and masonry. In the Heights and Greenville, frame houses leak where trim meets siding and at door thresholds. If water is coming through the brick around the opening rather than the joint, repointing the surrounding brick or treating the wall face may be the real fix. A leaking sill at a balcony door often traces back to the balcony membrane itself.