What are the gaps at the bottom of my brick wall?

Weep holes: intentional openings in the bottom course's vertical joints (and above windows and doors) that drain the cavity behind the brick. They are supposed to be there and supposed to stay open.

Should weep holes be sealed to keep bugs out?

Never sealed: caulking or mortaring weeps traps water in the wall cavity. Insect concerns are handled with purpose-made weep vents and screens that block pests while draining water.

Yes, by design expectation: brick and mortar absorb and pass water in wind-driven rain, and the system behind, cavity, barrier, flashing, and weeps, catches and drains it. A brick wall is a rain screen, not a tank.

Why is there white powder on my brick?

Efflorescence: minerals left where water moved through the masonry and evaporated. Light bloom is common; heavy or recurring bloom maps a drainage or flashing problem worth finding.

Brick Veneer and Weep Holes: How the Wall Drains

Page last reviewed: August 2026 · Reviewed by Harold R. Bennett, retired home inspector

Modern brick houses are almost never brick houses: they are wood-framed houses wearing a single brick layer, a veneer, hung on ties with an air cavity behind it, and the whole assembly works only because it is designed to leak and drain. Brick veneer weep holes are the drain, and the most common brick-wall problems in the field are the predictable results of people sealing them. This reference covers the system, the sins against it, and the readings brick gives an inspector.

The system: a rain screen in masonry

Brick and mortar are absorbent: wind-driven rain wets the face, soaks the units, and passes joints, reliably enough that the design assumes it. Behind the single brick wythe runs the drainage plan: a clear air cavity (an inch or two), the water-resistive barrier on the sheathing doing the actual waterproofing, exactly the vinyl-wall logic in masonry dress, through-wall flashing at the wall’s base and over every opening, catching cavity water and directing it out through the brick, and weep holes, the open head joints (or wicks, or vents) spaced along the bottom course and atop window and door lintels, where the flashing discharges. Corrugated metal ties stitch the veneer to the framing across the cavity. Water’s intended trip: through the brick, down the cavity’s back, onto the flashing, out the weeps, which is why every weep is a small proof the wall is working, not a defect to fill.

The sins: sealing the drain

Caulked and mortared weeps lead the finding list: painters, sealers, and bug-averse owners fill the “gaps,” and the cavity becomes a reservoir, water rising over flashing laps, wetting the barrier and sheathing long-term, feeding interior stains at wall bases and window heads, and, in winter, freeze-thaw working the saturated bottom courses. The correction is reopening (drilling out mortar-filled weeps at the original spacing where needed) and the insect answer is the purpose-made weep vent, screen inserts that drain while excluding pests. Mortar bridging commits the same sin from inside: droppings from original construction piling on the flashing, damming the cavity, an original defect that announces itself decades later as unexplained dampness above the base course. Sealed brick rounds out the family: film-forming waterproof coatings on absorbent brick trap moisture inside the units, spalling faces off through freeze-thaw, whereas breathable siloxane-class repellents, used judiciously on problem walls, respect the wall’s need to dry, the same seal-both-sides warning the vapor references carry.

The readings brick gives

Efflorescence, the white mineral bloom, is the same water-transit report here as on basement walls: light and historic is common, heavy and recurring maps active water, and its geography points, bloom above a lintel to that opening’s flashing, a base-course band to blocked weeps or grade problems. Spalling, brick faces popping off, reports saturation plus freeze-thaw, and its address does too, chimney tops and parapets by exposure, base courses by grade and splash, sealed walls by coating. Rust stains and cracked bricks at lintels report the steel angle above openings corroding and expanding, a standard repair with a schedule, and stair-step cracks in veneer read by the foundation-movement rules, veneer being a brittle witness to whatever the structure does. Mortar erosion is maintenance: joints recessed and sandy earn repointing, with the old-house caveat that historic soft-lime mortar must be matched, hard modern mortar in soft old brick spalling the brick instead of sacrificing the joint.

Ownership, briefly

The homeowner’s brick program is short: weeps counted and kept open (bottom course and over openings, spaced every couple of feet), grade and sprinklers kept off the wall’s base, sealers avoided unless breathable and justified, caulk confined to genuine joint locations and never the drainage, repointing bought when joints recede, and the interior wall bases below and around brick openings glanced at seasonally for the stains that say the cavity’s plan is failing. Lintel rust, heavy recurring bloom, bulging veneer, or ties failing (a veneer that pulls from the wall line) graduate to masonry professionals, with the engineer-before-contractor hygiene applying to anything structural.

The bottom line

Brick veneer is a raincoat with a drain: the wrap behind does the waterproofing, the flashing catches the cavity’s water, and the weeps let it leave. Keep every weep open, screen them instead of sealing them, read bloom and spalling as water reports with addresses, and never coat an absorbent wall shut, because a brick wall survives by drying faster than the weather wets it.