Repointing a Facade: Repairing, Replacing and Raking Out Mortar Joints

Good mortar joints are essential for a strong, watertight and durable facade. The joints act as the protective seal between the bricks. When they become damaged, porous or start to crumble, moisture can easily penetrate the wall. This leads to mould, penetrating damp, frost damage and accelerated deterioration of the masonry. This comprehensive guide explains everything about repairing, replacing and raking out mortar joints in exterior walls.

1. What Are Mortar Joints and Why Are They Important?

Mortar joints are the strips of mortar between the bricks in a wall. They serve three crucial functions:

• Protection: prevent rainwater from entering the wall

• Stability: keep the bricks firmly in place

• Insulation: help reduce heat loss and moisture problems

When joints deteriorate, the facade loses its protective function.

2. How to Recognise Damaged Mortar Joints

Signs of worn or failing joints include:

• loose or missing mortar

• cracks in the joints

• powdery or crumbling mortar

• damp patches on interior or exterior walls

• moss or algae growth on the joints

• bricks that begin to loosen

A simple test: Rub your finger along the joint. If sand or powder comes off, the joint is worn out.

3. Causes of Joint Damage

Mortar joints deteriorate due to:

• rain, frost and temperature fluctuations

• ageing of the masonry

• poor‑quality mortar

• salt deposits

• vibrations (traffic, construction work)

• previous incorrect repairs

4. Types of Joint Damage

1. Eroded joints

Wind and rain gradually wear down the mortar, making it thinner and more porous.

2. Cracked joints

Caused by subsidence, vibrations or thermal expansion.

3. Detached joints

Mortar separates from the brick due to poor adhesion or moisture issues.

4. Powdery joints

Mortar disintegrates into sand due to ageing or incorrect composition.

5. How Mortar Joints Are Repaired

Repairing mortar joints involves three main steps:

Step 1: Raking Out or Grinding Out Old Joints

Old mortar is removed using:

• a mortar chisel

• an angle grinder with dust extraction

• a hammer drill (for very hard joints)

Key requirements:

• remove at least 1.5 cm of depth

• avoid damaging the bricks

• remove all dust and loose material

Step 2: Applying New Mortar Joints

Fresh mortar is applied using a pointing trowel or jointing board. The mortar must:

• adhere well

• harden properly

• be water‑resistant

• match the brick type

Common joint styles include:

• flush joint

• weathered joint

• recessed joint

• struck joint

• brushed joint

Step 3: Finishing and Aftercare

After pointing:

• excess mortar is removed

• joints are shaped for the correct texture and appearance

• the facade can be sealed for extra protection

6. When Should Mortar Joints Be Replaced?

Joints need replacement when:

• they are loose or missing

• they are porous or powdery

• cracks are visible

• moisture problems appear

• the facade looks visibly aged

On average, mortar joints last 25–40 years, depending on weather conditions and maintenance.

7. Benefits of New Mortar Joints

• the facade looks fresh and renewed

• improved protection against moisture

• reduced risk of mould and penetrating damp

• extended lifespan of the masonry

• better insulation performance

• increased property value

8. Common Mistakes When Repointing

• not raking out deep enough

• using the wrong type of mortar

• pointing during rain or frost

• damaging bricks during removal

• insufficient drying time

• not sealing the facade afterwards

9. Repointing and Sealing the Facade

After repointing, sealing the facade is highly recommended. A high‑quality sealer:

• makes the wall water‑repellent

• prevents penetrating damp

• protects the new joints

• extends the lifespan of the masonry

Repointing + sealing is the most durable combination.

10. Summary

Mortar joints are essential for a strong, watertight and long‑lasting facade. Damaged joints lead to moisture problems, mould and structural issues. The repointing process consists of:

1. raking out old joints

2. applying new mortar

3. finishing and sealing the facade

With proper maintenance, a repointed facade remains protected for decades.