Steel angle iron
L-shaped rolled steel, typically 4×3.5″ or 6×4″, sitting on bearing brick on each side of the opening. Dominant on Chicago residential and commercial brick from roughly 1910 onward. Failure mode: rust and jacking.
Guide · Walls & structure · updated
What is a lintel? A complete guide to brick and masonry lintels.
A lintel is a horizontal structural member that spans an opening — window, door, garage — in a masonry wall and transfers the load of the wall above to the bearing wall on each side. In Chicago brick buildings, lintels are made of steel angle iron, limestone, reinforced concrete or, in pre-1900 stock only, wood. They fail by rust, deflection or spalling.
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- License TGC-098-734
- Est. 2014
- Lintel replacement scope
What is a lintel?
A lintel is a horizontal structural member spanning an opening in a masonry wall. It carries the load of the wall above the opening — bricks, parapet, sometimes roof — and transfers that load to the bearing portion of the wall on either side. Without a lintel, brick above an opening cannot stay up.
Lintel — four-part definition
- Span — the clear width of the opening the lintel crosses.
- Bearing — the length of lintel sitting on the wall on each side, typically 4–6 inches on residential brick.
- Backing — the brick course immediately above the lintel that the lintel directly carries.
- Soffit — the underside of the lintel, the part you see from below when the opening is open.
What are the main types of lintels?
In Chicago masonry, lintels are made of one of four materials: steel angle iron (dominant from 1910 onward), limestone or cut stone (greystones, Beer-Baron mansions), reinforced concrete (1930s+ industrial and commercial), or wood (pre-1900 stock only, mostly replaced during restoration).
Limestone / cut stone
Solid Indiana limestone or granite blocks spanning the opening. Common on 1880–1920 Lincoln Park greystones, Pierce Avenue Beer-Baron mansions and landmark commercial. Lifespan 100+ years with periodic repointing.
Reinforced concrete
Pre-cast or poured-in-place concrete bars with internal rebar. Common on 1930s+ industrial buildings, mid-century commercial brick and adapted-use Bucktown lofts. Lifespan 60–100 years.
Wood
Solid timber lintels, common in pre-1900 workmen's cottages. Almost always replaced with steel or stone during restoration scopes — the original wood is rarely structurally sound after 130 years of Chicago weather.
How does a lintel work structurally?
A lintel works by intercepting the vertical load of the brick wall above an opening and redirecting it horizontally to the bearing points on each side of the opening. The bearing length — typically 4 to 6 inches each side on residential brick — distributes that load over enough brick area to prevent crushing the bearing course.
The load path, in three sentences
1. The brick above the opening would otherwise have nothing to rest on and would collapse into the opening.
2. The lintel sits on the brick wall on each side of the opening, so its ends bear on solid wall.
3. Above the lintel, brick is laid normally; its weight transfers down through the lintel and out to the bearing brick on each side.
What are the signs your lintel is failing?
The clearest signs a lintel is failing on a Chicago wall are diagonal cracks radiating from the upper corners of the opening, a sagging brick course directly above the opening, rust streaks running down from the lintel ends, spalling brick concentrated above the opening, visible mid-span deflection, and water intrusion at the corners. Any one is enough to trigger a closer look.
Seven signs to look for, in order of severity
- Diagonal cracks at the upper corners of the opening, radiating up and out into the wall.
- Sagging brick course directly above the lintel — usually visible against neighboring courses.
- Rust streaks running down from the lintel ends, especially on light brick.
- Spalling brick concentrated above the opening while the rest of the wall is intact.
- Visible mid-span deflection — the lintel bowing downward, even slightly, under load.
- Water intrusion at the upper corners — staining, mineral deposits or peeling paint inside.
- Cracked sill or stoop stones below the opening — load redistribution from a failing lintel above.
What is a steel lintel and why does it rust?
A steel lintel is a piece of rolled angle iron (typically L-shaped, 4×3.5 inches or 6×4 inches) embedded in a brick wall above an opening. Steel lintels rust when water enters the wall through a failed mortar joint or missing flashing. Iron oxide expands roughly ten times the volume of the parent steel, jacking the brick above and cracking the wall.
Why "jacking" is the Chicago lintel problem
Chicago's freeze-thaw cycle drives water into the wall through any failed joint above the lintel. The water reaches the steel; the steel rusts; the rust expands; the brick above the lintel is forced upward and outward. The diagonal cracks at the upper corners are the visible signature of that jacking. The fix is always the cause first — flashing, mortar, downspout — then the lintel.
How is a lintel replaced?
Lintel replacement on a Chicago brick wall is a seven-step process: shore the opening from below, remove the brick course above in measured bays, cut and lift out the old lintel, install a new lintel sized to span plus 4–6 inches of bearing on each side, tooth in matched brick, repoint the surrounding joints, and inspect and document.
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Shore the opening
Install a needle beam or angle shore below the lintel to carry the load of the wall above while the lintel comes out.
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Remove brick above in measured bays
Take down the brick course directly above the lintel — and one or two courses higher — in toothed bays so the existing bond is preserved on each side.
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Cut and lift out the old lintel
Cut steel lintels with a torch or reciprocating saw, crane out limestone, demo concrete in sections. Clean and re-level the bearing pockets.
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Install new lintel with bearing
Set the replacement lintel so it spans the opening plus 4 to 6 inches of bearing on each side. Bed in mortar, level and plumb. Install through-wall flashing and weeps above.
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Tooth in matched brick
Lay matched brick into the toothed bays above the new lintel, locked into the existing bond with matched mortar mix.
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Repoint surrounding joints
Repoint the joints around the new work to the original profile so the repair reads as part of the wall, not as a patch.
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Inspect, photograph, document
Pull the shoring once mortar has cured, check alignment, photograph the work and record materials used for the owner's records.
How much does lintel replacement cost in Chicago?
Lintel replacement in Chicago runs $450–$1,200 per opening on residential ground-floor work with ladder access, $800–$1,800 per opening on upper floors with scaffold, and $1,500–$4,500+ per opening for commercial swing-stage scope. Limestone matched-stone replacement on greystones and mansions runs $2,000–$8,000+ depending on the original stone.
| Scope | Range |
|---|---|
| Residential ground floor (ladder access) | $450–$1,200 per opening |
| Residential upper floor (scaffold) | $800–$1,800 per opening |
| Commercial / swing-stage | $1,500–$4,500+ per opening |
| Limestone matched-stone replacement | $2,000–$8,000+ per opening |
| Cause-fix work (flashing, mortar, downspout) | priced separately |
Range. Final cost confirmed after a 48-hour on-site visit with the crew lead.
What moves the number up or down
- Access method — ladder vs. scaffold vs. swing-stage.
- Engineer coordination on commercial Facade Ordinance scope.
- Material — steel angle vs. quarry-matched limestone vs. cast concrete.
- Brick replacement above — number of toothed-in units required.
- Permit timing and city paperwork window on commercial scope.
The Chicago Facade Ordinance and lintels.
Chicago Facade Ordinance — the lintel-relevant version
The Chicago Facade Ordinance (Municipal Code 13-196-031, in force since 1996) requires the exterior walls and appurtenances of buildings 80 feet tall or above — roughly seven to eight storeys and up — to be inspected on a recurring critical-exam cycle by a licensed Illinois structural engineer or architect. The critical-exam interval is not a single number; it runs 4 to 12 years depending on facade category.
| Facade category | What it means | Cycle |
|---|---|---|
| Category I | Non-corroding metal armature or no metal in the wall | Every 12 years |
| Category II | Protected or corrosion-resistant metal armature | Every 8 years |
| Category III | Corroding metal — unprotected steel angle iron, embedded steel | Every 4 years |
An Ongoing Inspection is required between critical exams. Older Chicago masonry with unprotected steel lintels typically falls into Category III on the 4-year cycle; terracotta facades also lean toward the more frequent end.
Why this matters for lintels: failed steel lintels are one of the most common findings in Category III critical exams. The Ordinance scope drives a steady stream of lintel-replacement work across the wider North Side. Engineer-coordinated commercial scope →
How long does a masonry lintel last?
In Chicago, a steel angle-iron lintel lasts 50 to 80 years if the flashing and mortar joints are intact, but only 20 to 30 years without them. Limestone lintels last 100 years or more with periodic repointing. Reinforced concrete lintels run 60 to 100 years. Wood lintels are spec-replaced during any restoration scope.
| Material | Lifespan (Chicago) | Failure mode |
|---|---|---|
| Steel angle iron — flashing intact | 50–80 years | Eventual rust at bearing |
| Steel angle iron — flashing failed | 20–30 years | Rust, jacking, brick crack |
| Limestone / cut stone | 100+ years | Mortar joint loss, hairline crack |
| Reinforced concrete | 60–100 years | Internal rebar corrosion, spalling |
| Wood (pre-1900) | Replaced on restoration | Rot, deflection, insect damage |
Lintels vs parapets — what's the difference?
A lintel is a horizontal structural member spanning an opening in a wall (window, door, garage). A parapet is the section of wall that extends above the roof line at the building edge. They share materials (brick + mortar) and failure modes (water intrusion, freeze-thaw) but sit in completely different parts of the building envelope.
Lintel
Where: over an opening in a wall.
Carries: the wall load above the opening.
Material: steel angle iron, limestone, concrete or wood.
Typical failure: rust, deflection, jacking the brick above.
Parapet
Where: the part of the wall extending above the roof deck at the building edge.
Carries: primarily wind and weather, not vertical load.
Material: matched brick + coping stone or metal cap.
Typical failure: coping loss, water intrusion, leaning.
Lintel questions we get every week.
What is a lintel?
A lintel is a horizontal structural member that spans an opening in a masonry wall — window, door, garage — and transfers the load of the wall above to the bearing portion of the wall on either side. In Chicago brick buildings, lintels are made of steel angle iron, limestone, reinforced concrete or, in pre-1900 buildings only, wood.
What are the signs your lintel is failing?
The clearest signs a lintel is failing on a Chicago wall are diagonal cracks radiating from the upper corners of the opening, a sagging brick course directly above the opening, rust streaks running down from the lintel ends, spalling brick concentrated above the opening, visible mid-span deflection, and water intrusion at the corners. Any one is enough to trigger a closer look.
Why do steel lintels rust in Chicago?
Steel lintels rust when water enters the wall through a failed mortar joint or missing flashing above the opening. Iron oxide expands roughly ten times the volume of the parent steel, which jacks the brick course above the lintel and cracks the wall. Chicago freeze-thaw cycles accelerate the process. The cause-fix — flashing, mortar joints — has to come with the lintel replacement.
How is a lintel replaced?
Lintel replacement on a Chicago brick wall is a 7-step process: shore the opening from below, remove the brick course above in measured bays, cut and lift out the old lintel, install a new lintel sized to span plus 4–6 inches of bearing on each side, tooth in matched brick above, repoint the surrounding joints, and inspect and document.
How much does lintel replacement cost in Chicago?
Lintel replacement in Chicago runs $450–$1,200 per opening on residential ground-floor work with ladder access, $800–$1,800 per opening on upper floors with scaffold, and $1,500–$4,500+ per opening for commercial swing-stage scope. Limestone matched-stone lintel replacement on greystones and mansions runs $2,000–$8,000+ depending on the original stone.
What is the Chicago Facade Ordinance and how does it apply to lintels?
The Chicago Facade Ordinance (Municipal Code 13-196-031, in force since 1996) requires the exterior walls of buildings 80 feet tall and above to be inspected on a critical-exam cycle by a licensed Illinois structural engineer or architect. The cycle is 4 to 12 years depending on facade category. Failed steel lintels are one of the most common findings in Category III critical exams — buildings with corroding metal armature on the 4-year cycle.
How long does a masonry lintel last?
In Chicago, a steel angle-iron lintel lasts 50–80 years when the flashing and mortar joints are intact, but only 20–30 years without them. Limestone lintels last 100 years or more with periodic repointing. Reinforced concrete lintels run 60–100 years. Wood lintels (pre-1900 stock only) are typically replaced during any restoration scope.
Related guides and services.
Guide
Signs your brick needs repair
Broader diagnostic guide — beyond lintels — covering spalling, cracks, mortar failure and when to call a professional.
ReferenceMasonry glossary
Definitions of every term used above — wythe, soffit, bearing, flashing, mortar types and more.
ServiceCommercial & facade
Lintel replacement as part of Chicago Facade Ordinance critical-exam follow-up. Engineer-coordinated, swing-stage scope.
Lintel scope · free estimate
Failing lintel? Get a written scope in 48 hours.
Shore, replace, tooth in, repoint, document. The cause fixed first. One crew on the wall.