Replacing Windows on a Brick House: Which Trade Goes First?

Here is a conversation that happens every spring in Chicagoland, always in the same order and always too late.

A homeowner replaces the windows on a brick house. Good windows, competent installer, house looks better immediately. Then eighteen months later there is a crack above one of the new units, or a stain running down the brick beneath another — and the repair now means cutting into work that was just paid for.

A window goes into an opening the masonry built. If the steel above that opening is corroding or the stone below it has stopped shedding water, the sequence matters, and the answer is not complicated: masonry first.

Paul Lally's Masonry Inc. is a family-owned, 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 actually lives in a window opening

Four masonry components, and a homeowner can see two of them.

The lintel. The structural member above the opening carrying the masonry that would otherwise sit in the hole. On most Chicagoland houses that is a steel angle iron; on older stone-fronted work it may be a stone lintel. Hidden behind the head joint.

The sill. The pitched stone or cast unit below, whose entire job is throwing water clear of the wall. Visible.

The jambs. The masonry sides of the opening, and the joints where they meet the frame.

The flashing. Where it exists — a barrier above the opening directing water back out of the wall, ideally with end dams. Hidden.

A window installer works on the frame in the middle. All four of those sit around it, and all four are masonry.

Why the order is what it is

The lintel will not wait

Steel corrodes, and rust occupies several times the volume of the metal it came from. It cannot push down through the window frame, so it pushes up, lifting and cracking the brick above. The trade calls it rust jacking, and it is progressive — it does not pause because a new window went in below it.

Replacing that lintel properly means shoring the masonry above the opening, taking down courses of brick, cutting out the steel, setting new protected steel with flashing, and relaying the brick. You cannot do that around a brand-new window without disturbing it. See failing lintels and cracked brick above windows.

A failed sill damages the wall below, not the window

A sill that has cracked, lost its pitch, or had its drip edge bridged by paint or caulk stops carrying water clear and starts directing it onto the brick beneath. That is why spalled brick under a window is so common while the brick either side is sound.

New windows do nothing about that. The sill keeps feeding the wall. And resetting or replacing a sill means working right at the bottom of the frame that was just sealed in.

The opening dimension can change

This is the practical one that surprises people. Rebuilding a head, resetting a settled sill, or replacing displaced jamb brick can change the rough opening by a small amount.

Measure for windows before that work, and the units may not fit the finished opening. Measure after, and they will.

Sealant needs a sound substrate

Perimeter sealant bonds to the masonry at the jamb and head. If that masonry is cracked, spalling or has open joints, the bead has nothing reliable to adhere to and fails early — which reads as a window problem and is not one.

Somebody's warranty is on the line

A window installer seals into the opening they were given. If water later enters through a corroding lintel head above that seal, the resulting argument between trades is one the homeowner ends up paying to referee. Sequencing masonry first removes the argument.

How to tell whether your openings need work

Before you order windows, walk the outside of the house and look above and below each opening rather than at it.

Above the opening

• A straight horizontal crack in the mortar joint at the head
• Rust staining bleeding down the brick below that joint
• The course above the window lifted out of plane
• Cracked or displaced brick at the upper corners, sometimes stepping diagonally
• A visible steel edge that is flaking or delaminating in layers
• The window out of square at the head

Below the opening

• Cracked, spalled or delaminating sill stone
• The sill looking flat rather than pitched
• Paint or caulk bridging the underside, where a drip groove should be open
• Open joints at the sill ends, where it meets the jamb brick
• Spalled brick directly beneath, with sound brick either side

Around it

• Open or eroded joints at the jambs
• Failed perimeter sealant — cracked, hardened, pulled away at one edge
• On veneer, blocked or buried weep holes below the opening

Any of the "above" list means the lintel is working on the wall right now. Our guide to masonry around windows and openings covers the whole assembly.

The sequence that works

1. Assess the openings before ordering anything. All of them on the affected elevation, not just the one that looks bad — lintels on a given wall went in the same year, from the same steel, in the same exposure, and corrode as a cohort.
2. Do the masonry. Lintels shored and replaced, sills repaired, reset or replaced, jamb brick and head joints repointed, flashing restored where the detail allows.
3. Let the mortar cure. Days rather than weeks in a normal Chicagoland season.
4. Measure the finished openings for the windows.
5. Install the windows.
6. Seal the perimeter — backer rod, correct sealant, properly tooled, by whichever trade the contract assigns it to.
7. Confirm drainage. On veneer, that weep holes below the openings are open and not buried.

When the order genuinely flips

Being honest about the exceptions.

The masonry is sound. If the heads and sills check out and the field of the wall is fine, there is nothing to sequence. Replace the windows and re-seal the perimeters.

The windows are an emergency. A broken or unsecured opening gets handled now. Do the masonry in the next reasonable window, accepting that some new work may be disturbed.

One trade genuinely covers both. Some contractors do window work and masonry both. That is fine — what matters is that somebody has assessed the lintels and sills, and that the sequence within the job is masonry-then-window rather than the reverse.

Winter. Mortar needs workable temperatures to cure. If windows must go in during a Chicago January, the masonry may reasonably wait for spring — as a deliberate decision, with the knowledge that some new work will be touched.

Getting two trades to agree in writing

Most of the friction on these projects is not technical. It is that two contractors each assumed the other owned a detail.

Four things worth having written down before either starts:

Who measures, and when. If the masonry is changing an opening, the window measurement happens after. State that explicitly, with the mason confirming when openings are final.

Who owns the perimeter sealant. The joint where frame meets masonry. Usually the window installer, sometimes the mason, occasionally neither by accident — which is how a house ends up with an unsealed perimeter nobody noticed until it rained sideways.

Who owns flashing at the head. Through-wall flashing above the opening is masonry work. Head flashing integrated with the window unit is window work. On an older wall with no flashing at all, somebody has to decide whether it is being introduced, and that is a masonry decision.

What happens if the mason finds more. Openings reveal their condition when they are opened. Agreeing in advance that the window schedule can shift if a second lintel turns out to be worse than it looked saves a scramble later.

None of that requires a formal contract amendment — an email both trades are copied on does the job.

What "just re-caulk it" does and does not solve

Worth addressing directly, because it is the cheapest proposal a homeowner will receive and sometimes it is the right one.

Perimeter sealant at the frame-to-masonry joint has a real service life, measured in years rather than decades, and south and west elevations go first. Renewing it — cutting out the old bead completely, cleaning the faces, installing backer rod, tooling a new bead — is legitimate, inexpensive maintenance and frequently the correct answer on a sound wall.

What it does not do is address anything structural. A bead of sealant across a rust-jacked head joint conceals the crack and changes nothing about the steel behind it. Caulk pressed into an open mortar joint at a jamb traps water behind it and makes the eventual repointing harder. And sealant run along the underside of a sill bridges the drip edge, which actively routes water back onto the brick it was supposed to protect.

So the question to ask is not whether to re-caulk. It is what the sealant is being asked to do — finish a sound assembly, or stand in for a repair.

The Chicagoland context

Three regional realities make this a bigger deal here than in milder markets.

The housing stock. Chicago brick bungalows, greystones, two-flats and post-war ranches are frequently 60 to 120 years old, built with unprotected steel lintels and no flashing above the openings. That steel has now been wet far more often than it has been dry.

Freeze-thaw. A Chicago winter thaws and refreezes dozens of times a season. Every cycle is an expansion event inside wet masonry, and it is what turns a hairline at a window head into a displaced course.

Wide openings. Post-war ranches and split-levels across the suburbs favour big front picture windows and wide garage openings. Longer spans carry more masonry, so a lintel losing section shows movement sooner and worse.

A useful pattern: if your house is of that era and nobody has ever looked at the lintels, the window project is the natural moment. The staging is coming anyway.

Materials, briefly

Correctly sized, protected steel for lintel replacement, with flashing and end dams so water leaving the wall goes out rather than back in. Mortar matched in type, colour, sand and joint profile — and softer than the brick around it, because mortar harder than the unit drives stress into the unit and spalls its face. Stone sills repaired in place, patched, repaired with a matched Dutchman insert, reset, or replaced with proper pitch and a real drip edge. Backer rod and correctly tooled elastomeric sealant at the perimeter, never caulk smeared into a mortar joint.

What drives the cost

Number of openings and their spans. Height and access. How much masonry must be shored and relaid. Whether brick and stone can be matched or must be sourced. Whether flashing is being installed, which can mean opening more of the wall. Whether the work is one elevation or several. Weather windows, since mortar needs workable temperatures to cure.

We publish no figures — a number that means anything requires seeing the openings. Free on-site estimate, in writing, with the openings itemised — call (708) 448-8866.

The one thing to do before you sign a window contract

Have somebody look at the heads and the sills.

It costs nothing, it takes an hour, and it is the difference between a window project that finishes and one that comes back around with a masonry bill and some new work to cut into.

Paul Lally's Masonry Inc. is family-owned, insured, and has worked Chicagoland openings since 1988. Our name is on every job. Related services: lintel repair and replacement, limestone and sill repair, brick repair, tuckpointing and repointing, and caulking and joint sealant.

Built on Craftsmanship. Backed by Experience. Get a free on-site estimate or call (708) 448-8866.