Facade Cracks: Types, Causes & Repair (Complete Guide)

Facade cracks are common in both older and modern buildings. Some cracks are harmless and purely cosmetic, while others may indicate serious issues such as foundation problems, subsidence, moisture infiltration or structural defects. This complete guide explains the different types of cracks, their causes, how to assess them and the most effective repair methods.

1. What Are Facade Cracks?

Facade cracks are openings or fractures in:

• brickwork

• mortar joints

• plaster or render

• concrete elements

• structural components

They occur due to movement, stress or deterioration in the wall or underlying structure.

2. The Most Common Types of Facade Cracks

1. Hairline cracks

• very thin

• superficial

• often in paint or render

• usually harmless

2. Horizontal cracks

• run parallel to the ground

• may indicate foundation issues

• sometimes caused by floor expansion or lintel pressure

3. Vertical cracks

• run straight up

• often caused by settlement or shrinkage

• usually less severe but still require assessment

4. Diagonal cracks

• typically at a 45° angle

• common in cases of subsidence or uneven load

• can be serious

5. Cracks around window frames

• caused by frame movement

• may indicate thermal bridging or subsidence

6. Mortar joint cracks

• crumbling or missing mortar

• often due to frost damage or ageing

• can lead to moisture problems

7. Cracks caused by corroding wall ties

• horizontal or diagonal

• often at wall tie height

• potentially dangerous

3. Causes of Facade Cracks

1. Differential settlement

Uneven ground movement causes stress in the masonry.

2. Foundation problems

Subsidence, soil shrinkage, timber pile decay.

3. Thermal expansion and contraction

Temperature changes cause materials to move.

4. Moisture issues

Penetrating damp, leaks, frost damage.

5. Construction defects

Incorrect dilatation joints, poor detailing, wrong load distribution.

6. Corroding wall ties

Expanding metal pushes the masonry apart.

7. Vibrations

Traffic, construction work, heavy machinery.

8. Material ageing

Mortar and bricks lose strength over time.

4. How to Assess the Severity of a Facade Crack

Look for these indicators:

1. Crack width

• < 1 mm → usually cosmetic

• 1–5 mm → requires attention

• 5 mm → potentially structural

2. Crack pattern

• diagonal → often subsidence

• horizontal → foundation or wall tie issues

• vertical → settlement or shrinkage

3. Location

• near window frames → movement or subsidence

• at floor levels → thermal bridging or structural pressure

• in corners → stress concentration

4. Progression over time

Cracks that grow are always suspicious.

5. Moisture or staining

May indicate penetrating damp or leaks.

5. Professional Diagnosis of Facade Cracks

A specialist will examine:

• crack width and depth

• structural movement

• foundation and soil conditions

• cavity wall and wall ties

• moisture levels

• thermal imaging

• overall masonry stability

This determines whether the crack is cosmetic, technical or structural.

6. Repair Methods for Facade Cracks

1. Cosmetic repair

For hairline or superficial cracks:

• cleaning

• filling

• repointing

• repainting or re‑rendering

2. Repointing

For deteriorated mortar joints:

• grinding out old mortar

• applying new mortar

• optional facade impregnation

3. Crack stitching with helical bars

For cracks in masonry:

• inserting helical bars into mortar joints

• reconnects and stabilises the wall

• highly effective for diagonal cracks

4. Wall tie replacement

For corroded or missing ties:

• deactivating old ties

• installing new stainless steel wall ties

• prevents further cracking

5. Foundation repair

For subsidence:

• soil stabilisation

• underpinning

• installing new piles

6. Full facade renovation

For severe damage:

• renewing joints

• replacing damaged bricks

• cleaning the facade

• applying impregnation

7. How to Prevent Facade Cracks

• ensure proper drainage

• maintain mortar joints

• inspect wall ties in older homes

• fix leaks promptly

• maintain window frames and expansion joints

• monitor cracks with crack gauges

• avoid excessive watering near foundations

8. Summary

Facade cracks range from harmless hairline cracks to serious structural defects. The key is to:

1. identify the type of crack

2. determine the underlying cause

3. apply the correct repair method