How To Look At A House

McGarry and Madsen's home inspection blog for buyers of  

site-built, mobile/manfuactured and modular homes

What causes mortar cracks?

Wednesday, January 22, 2020

Mortar is designed to be slightly weaker structurally than the masonry it is bonding. This goes for all types of masonry, including brick, concrete block, or stone, and the logic behind it is that any cracks caused by movement in the wall are easier and less expensive to repair at the mortar joints.

    A crack in the mortar is called a “bond break” and, because they allow water into a wall and the subsequent deterioration over time, finger-size pieces of mortar will eventually begin to fall out or the mortar will crumble away unless repaired. 

    Occasionally, we see cracks that run though both the masonry units and the mortar, like in the photo below. This happens when the mortar strength exceeds or is close to the rating of the masonry, and can also be due to an occasional defective block or brick.

    While this explains why cracks usually follow mortar lines, it does not answer the question of what causes the movement in the wall in the first place, which is more complicated. Here’s a list of several of our other blog posts about understanding different types of crack patterns:

 What causes stair-step cracks in a block or brick wall?

What causes a horizontal crack in a block or brick wall? 

• What causes a vertical crack in an exterior concrete block or brick wall?

What would cause long horizontal lines of brick mortar to fall out?  

What causes the surface of old bricks to erode away into sandy powder? 

What does freeze damaged brick look like?

How do I recognize serious structural problems in a house?

Where are the places to look to find structural cracks in a house? 

    Visit our EXTERIOR WALLS AND STRUCTURE page for other related blog posts on this subject, or go to the INDEX for a complete listing of all our articles.

Water Heaters

Water Heater Age

"What Are The

Signs Of..."

Septic Tank Systems

Structure and Rooms

Plumbing Pipes

Termites, Wood Rot

& Pests

Sinkholes

Stairs

When It First

Became Code

"Should I Buy A..."

Park Model Homes

Site

Shingle Roofs

Safety

Stucco

Remodeling

Wind Mitigation

Roof and Attic

"Does A Home

Inspector...?"

Pool and Spa

"What Is The Difference Between..."

Radon

Brick

Plumbing

Concrete and

Concrete Block

Metal Roofs

Foundations

Modular Homes

Rain Gutters

Mold, Lead & Other Contaminants

Condominiums

Older and

Historic Houses

Crawl Spaces

Mobile-Manufactured Homes

Building Permits

Life Expectancy

Clay Soil

Insurance

Floors

Insulation

Toilets

Exterior Walls

& Structures

Generators

Common Problems

HUD-Code for

Mobile Homes

Garages and Carports

Flat (Low Slope) Roofs

Electrical Panels

Sprinkler Systems

Electrical Receptacle Outlets

4-Point Inspections

Hurricane Resistance

Frequently Asked Questions (FAQ)

Home Inspection

Heating and Air Conditioning

Building Codes

Fireplaces and Chimneys

Inspector Licensing

& Standards

Energy Efficiency

Washers and Dryers

Electrical

Kitchens

Doors and Windows

(placeholder)

Cracks

Electrical Wiring

Click Below  

for Links

to Collections

of Blog Posts

by Subject

Plumbing Drains

and Traps

Appliances

Smoke & CO Alarms

Aging in Place

Top 5 results given instantly.

Click on magnifying glass

for all search results.

Bathrooms

Lighting

AFCI, CAFCI,

DFCI, & GFCI

Sinks

Air Conditioner & Furnace Age/Size

Attics

Electrical Switches

Siding

Search

This

Site

Water Intrusion

Electrical - Old

and Obsolete

(placeholder)

Foundation Certifications

Tiny Houses

About Us

(placeholder)

Wells