Stair-Step Cracks in Brick and Block: What They Mean

Quick answer

Stair-step cracks in brick and block walls are cracks that follow the mortar joints in a zigzag, rising like the steps of a staircase. The crack goes around the masonry units instead of through them.

The shape shows where the wall found its weakest path. It does not show why the wall moved, which can be settlement, heat and moisture, or something else.

Quick facts

The key facts about Stair-Step Cracks in Brick and Block Walls, with sources:

Shape: A stepped line that follows horizontal and vertical mortar joints ¹
Where it forms: In brick, concrete block and similar jointed masonry ²
Settlement link: Settlement cracks usually follow a rough diagonal along mortar joints ²
Other cause: Thermal or moisture expansion can make a crack that follows the bricks in a stair-step pattern ¹
Cyclical cracks: Thermal cracks open and close with the seasons, wider in cold and narrower in heat ¹²
Repair caution: Filling cyclical cracks with rigid mortar can cause cracking elsewhere ²
Who reads it: A licensed structural engineer; a soils engineer where settlement is involved ²

Key takeaways

A stair-step crack climbs along mortar joints. It is the shape a diagonal crack takes in brick and block.
The shape is a clue. Differential settlement can cause it. So can thermal or moisture movement, as the National Park Service notes ¹².
HUD says many signs of masonry distress are wrongly blamed on settlement when moisture or thermal movement is the cause ².
Whether a stair-step crack is active matters more than its look. Repeat measurements show that ¹.
Do not assume a specific crack is harmless, and do not assume every crack needs underpinning. Ask a licensed structural engineer when it changes or you doubt it.

What a stair-step crack is

Brick and block walls are built from units joined by mortar. Mortar joints are the weak lines in the wall. When the wall is pulled or twisted, a crack tends to find those lines instead of breaking through the stronger units. The path zigzags across horizontal and vertical joints, and the result looks like stairs.

The National Park Service shows the pattern in its article on brick masonry problems: a crack that follows the brick in a stair-step pattern.

In its example the movement was probably caused by thermal or moisture expansion, not settlement ¹.

HUD’s inspection guide says settlement cracks in masonry usually follow a rough diagonal along mortar joints, though individual units may split ².

Both statements are true. The same shape has different possible sources. That is why this page treats the pattern as a clue and links to the broader guide on foundation cracks. The related term for slanted cracks in general is diagonal foundation cracks.

General information, not a diagnosis of your house

General information, not a diagnosis of your house. A stair-step crack can reflect settlement, heat and moisture movement, or something else. Only a licensed professional who sees the wall can say which.

Stair-step cracks: pattern, possible contributing factors and what to record

The middle column lists possibilities named by the cited sources or direct restatements of them. None is a finding about any wall.
Pattern	Possible contributing factors	What to record
A step crack rising from a corner or a window or door corner	Settlement beside an opening or at a corner ²	Which corner, which direction it climbs, date and photos
A step crack at a porch, bay or addition	Differential settlement under the projecting part ²	Whether one side sits higher; any change over time
A step crack that is wider in winter and narrower in summer	Thermal and moisture movement of the wall ¹²	Season and temperature when you measure
A step crack with split bricks or block units	Greater stress than the mortar alone could take ²	Which units are split; photos
A step crack above ground that continues into the foundation	Movement that crosses the wall, such as differential settlement	The full path, with a wide photo and close-ups

Diagram Four crack patterns, sketched

Illustrative, not to scale, not a design. It sketches horizontal, vertical, diagonal and stair-step cracks. A pattern is a clue, not a diagnosis.

How a stair-step crack forms

The wall is pulled or twisted. The cause may be uneven support, expansion, contraction or drying ²¹.
Stress builds at the weak lines. Mortar joints are weaker than the masonry units, so stress concentrates there.
A crack opens along the joints. It runs along a bed joint, steps up through a head joint, then runs along the next bed joint ¹.
Units may split. If movement is large, individual masonry units can crack as well ².
The crack may cycle or grow. Thermal cracks open and close with the seasons. Settlement cracks may widen if movement continues ².

Example: what the readings can look like over a year

The year-long readings below are an illustration of the two behaviors the sources describe, not data from a house ²¹. No width is shown, and none is a norm.

Behavior over a year	What it may suggest	What a professional does next
Opens in cold months, narrows in hot months, returns to the same size each year	Cyclical thermal or moisture movement ²¹	Considers a flexible sealant or expansion joints once the cause is clear ²
Slowly widens, with no seasonal return	Movement that may be continuing, such as settlement	Investigates the cause; may involve a soils engineer ²
No change in any reading	May be inactive for now	May allow pointing, since inactive cracks may be pointed ¹

A single reading cannot place a crack in one row. A year of dated readings can. The NPS advises watching cracks over time to see whether they are active ¹.

Where stair-step cracks show up

Stair-step cracks show in brick veneer, brick walls, and concrete block foundation and basement walls. HUD says settlement cracking is most likely at corners and adjacent to openings ². Thermal cracks are typical at openings, at offsets and near wall ends, where expansion and contraction concentrate ².

A stair-step crack in a basement block wall is a foundation clue. A stair-step crack in brick veneer may relate to the foundation or only to the veneer. An engineer can follow the crack from the veneer down to the footing to see which applies.

For slab floors, see cracks in slab foundations. They follow different patterns.

Why naming the pattern helps

What a clear description gets you

You can say exactly where the crack starts and which way it climbs.
You know to check whether it is cyclical before you assume settlement.
You can tell a mason, inspector or engineer the same thing in one phrase.

What the name cannot do

The name does not identify the cause.
It does not tell you whether the crack is active.
It does not choose a repair.

What this pattern does not tell you

A stair-step crack does not say whether the wall settled. HUD says many signs of masonry distress are blamed on settlement when moisture or thermal movement is the cause ².
It does not give a safe width. No width is given here.
It does not tell you whether the crack is cyclical. Only readings across the seasons do. HUD notes that cyclical movements may take six months or more to measure ².
It does not say the mortar is bad. Poorly made mortar can show random cracking at the joint, but that is a separate clue ².

What drives the cost of dealing with a stair-step crack

We print no prices. If a crack is inactive, repair may be small, such as repointing. If it is cyclical, the repair may use flexible sealant or add an expansion joint. If it comes from settlement, cost depends on the soil, the loads and an engineer’s design.

The National Park Service says structural repairs precede minor or cosmetic repairs ¹. Drivers include how many cracks there are, the wall height and material, access, and whether the cause is found and fixed first. Investigation and monitoring add to the early cost.

See the cost guide and the cost calculator for factors tied to your inputs.

What to do if you find one

Photograph the full path with a wide shot and close-ups, with a ruler or coin and the date.
Mark the ends of the crack lightly if the surface allows, with the date.
Note the season and weather every time you look ².
Add a gauge or repeat photos over the year. See foundation movement monitoring.
Check the house for sticking doors, sloped floors and other cracks, and for water near that wall.
Ask a licensed structural engineer if the crack changes, shows an offset or comes with other signs. HUD advises a structural engineer for masonry problems ².

A pattern is not a diagnosis

Do not repoint or fill a crack you have not recorded, and do not dig, jack or brace the wall yourself. HUD notes that filling cyclical cracks with mortar can simply make the masonry crack somewhere else ². Photographing, dating and installing a crack monitor are safe homeowner tasks.

Habits that protect masonry

Keep gutters and downspouts working so water does not run down the wall. See downspout drainage.
Keep soil next to the wall sloped away from it.
Keep a dated log of the crack with weather notes.
Use a flexible sealant only after a professional says the crack is cyclical. HUD says cyclical cracks should be cleaned and protected by flexible sealants ².
Fix leaks, since water that freezes in masonry can displace it ².

Risks of ignoring a stair-step crack

If the crack comes from settlement that continues, it can grow, and neighboring parts of the structure can be affected. HUD notes that large differential settlements cause movements in contiguous elements such as beams, joists, floors and roofs ².

HUD’s foundation guide adds that settlement usually happens over time and is not a dramatic event, which leaves time to research the cause ⁴. Water can also enter through the crack, and freezing water can damage the masonry further.

The reverse mistake is costly too. If the crack is cyclical, a rigid fill can cause cracks elsewhere ². Repair based on a wrong guess can waste money and fail.

Never assume a specific crack is harmless, and never assume every crack needs underpinning.

When to call a licensed structural engineer

Call when movement is significant, widening or changing; when walls are displaced or bowing; when new cracks come with sticking doors or windows; when walls separate at corners; or if you doubt the safety of the house. See do I need a structural engineer.

Standards and codes on masonry cracking

HUD’s study of concrete masonry homes says cracking can occur from temperature and moisture change or differential settlement of foundation soils.

It describes two crack-control methods: horizontal steel such as bond beams and joint reinforcement, and control joints that accommodate movement.

It adds that for low-rise buildings in most regions the model building codes do not prescribe them, and that the masonry industry makes recommendations ³.

So a stair-step crack does not by itself show a code failure. Whether a wall had control joints or reinforcement is a design detail to check with the local building department or an engineer. This page quotes no code section numbers.

Edition and adoption vary. Check the code your jurisdiction adopted.

Scope of the source

The HUD masonry study reviewed case-study homes and describes practice at that time. It is background, not a rule for your wall. Your jurisdiction may adopt other editions and amendments.

Stair-step cracks compared with other patterns

In masonry, a diagonal crack that follows joints is a stair-step crack. The two overlap.
Pattern	What the sources associate with it	Where to read more
Stair-step	A diagonal path through mortar joints; settlement or thermal and moisture movement ²¹	This page
Diagonal	A slanted line, often tapering; also seen in poured concrete ²	Covered in the diagonal-crack term linked above
Vertical	Shrinkage, thermal movement, or settlement at projections ²	Vertical foundation cracks
Horizontal	Backfill, vibration, swelling or freezing soil; potentially serious ²	Horizontal foundation cracks

Myths about stair-step cracks

Myth A stair-step crack always means the foundation settled.: Reality The National Park Service shows one probably caused by thermal or moisture expansion ¹.
Myth If it follows the joints, it is only a mortar problem.: Reality Mortar joints are where a crack goes. They are not the cause of the movement.
Myth Repointing fixes the crack.: Reality If movement continues, a repoint can crack again. HUD says remortaring cyclical cracks holds them open and causes more cracking ².
Myth A stair-step crack in veneer has nothing to do with the foundation.: Reality It may or may not. An engineer follows the crack down to see.
Myth Stair-step cracks are the worst kind.: Reality Shape is not a severity scale. Movement history, displacement and water matter more.

Climate and soil context

Thermal cycles matter more where seasons swing widely. HUD says above-ground brick walls expand in warm weather and contract in cool weather, building stresses that can cause varied cracking patterns, and that facing south or west adds expansion ².

In expansive-clay regions, swelling and shrinking soil adds foundation movement. Colorado SP-11 describes that for the Front Range ⁵. The NRCS Web Soil Survey shows soil types for your parcel.

Choosing your next step

Match what you see with a first move.

Decision guide Which step fits what you see

If A stair-step crack that photos show unchanged, no other signs: Then Record and monitor through the seasons; ask an engineer when convenient
If A crack that opens and closes with the seasons: Then Keep readings; ask a professional about flexible sealant or expansion joints
If A crack that keeps widening, or sticking doors and sloped floors: Then Ask a licensed structural engineer; a soils engineer may be needed
If Walls displaced or separating at corners: Then Call a licensed structural engineer promptly

Engineer first, contractor second

A licensed structural engineer with no repair to sell is the usual first call. Try the engineer-or-contractor tool.

Questions about Stair-Step Cracks in Brick and Block Walls

What are stair-step cracks?

Stair-step cracks are cracks in brick or block walls that follow the mortar joints in a zigzag, like steps. The National Park Service describes one that follows the brick in a stair-step pattern ¹. The shape tells you where the wall cracked, not why.

What causes stair-step cracks in brick?

Two main sources appear in agency guidance: differential settlement of the foundation ² and thermal or moisture expansion of the wall ¹. Other movement can cause them too. Which applies to your wall needs measurement and an on-site review.

Do stair-step cracks mean foundation settlement?

Not always. They can, since HUD says settlement cracks usually follow a rough diagonal along mortar joints ². But HUD also says many signs of masonry distress are wrongly blamed on settlement when thermal and moisture movement is the cause ².

Are stair-step cracks serious?

Seriousness depends on movement, displacement and cause, not on shape. Some are cyclical and cosmetic. Some mark ongoing settlement. A crack that is widening or changing, or one that comes with sticking doors or sloped floors, is a reason to ask a licensed structural engineer.

How can I tell if a stair-step crack is active?

Measure it over time. Photograph it from the same spot, use a gauge, and note the season. The National Park Service advises watching cracks over time to see whether they are active ¹. HUD notes cyclical movements may take six months or more to measure ².

Can I repoint a stair-step crack myself?

Ask a professional first. If the crack is cyclical or active, repointing may fail. HUD says filling cyclical cracks with mortar holds them open and causes cracking elsewhere, and recommends flexible sealants after the cause is known ². Record the crack before you cover it.

Do stair-step cracks in a basement wall need underpinning?

Not by default. Underpinning is a footing repair, and it fits only some causes. An engineer decides after assessing movement, soil and loads. Never assume every crack needs underpinning, and never assume a specific crack is harmless.

What is the difference between stair-step and diagonal cracks?

A stair-step crack is a diagonal crack that follows mortar joints in brick or block, so it steps. A diagonal crack can also cut across poured concrete in a straight slant. In masonry, HUD describes settlement cracks as a rough diagonal along mortar joints ².

Does insurance cover stair-step cracks?

It depends on policy wording, exclusions, endorsements, cause and state law. Many policies exclude settlement, earth movement and wear. Do not assume coverage either way. Read your policy and ask your insurer or state insurance department.

Who should look at a stair-step crack?

A licensed structural engineer is the usual first call, ideally one who does not sell repairs. HUD advises a structural engineer for masonry problems and a soils engineer where differential settlement is involved ².

Sources

National Park Service, Common Problems with Brick Masonry (updated June 29, 2018), retrieved October 14, 2026.
HUD User, Residential Inspection (rehabilitation inspection guide), chapters 2 and 4 (file rehabinspect_2.pdf), retrieved October 14, 2026.
U.S. Department of Housing and Urban Development, Office of Policy Development and Research, Building Concrete Masonry Homes: Design and Construction Issues, retrieved October 14, 2026.
U.S. Department of Housing and Urban Development, The Rehab Guide, Volume I: Foundations (prepared by Steven Winter Associates), retrieved October 14, 2026.
Colorado Geological Survey, Special Publication 11: Home Construction on Shrinking and Swelling Soils (Holtz and Hart for the American Society of Civil Engineers, 1978), retrieved October 14, 2026.

Expert review

Written by the HyreFoundation Research team. Not yet reviewed by an outside expert. We say so rather than imply a review that has not happened; see our editorial policy.

How the numbers were checked: Crack-pattern statements come from the National Park Service and HUD guides loaded on 2026-10-14. Patterns are presented as clues.

No crack-width threshold, soil value or price is given. ICC code text could not be loaded, so no code section is quoted. This page has not been reviewed by a named licensed engineer.

Suggest a correction. We fix errors and say what changed.