Common Mistakes When Repointing Brickwork: 17 Costly Errors to Avoid

The most common mistakes when repointing brickwork include using the wrong mortar mix, insufficient joint preparation, damaging bricks, poor mortar application and working in unsuitable weather. Using hard cement mortar on older brickwork can also cause moisture problems and cracking. Proper preparation, compatible mortar and correct curing help ensure durable, long-lasting repointing.

Repointing brickwork is an essential maintenance task that protects buildings against weather damage, moisture penetration and gradual deterioration. Although the process appears relatively straightforward, small mistakes during preparation, mortar selection or application can cause significant problems over time.

Across the UK, millions of homes feature traditional brick construction. Victorian terraces, Edwardian properties, Georgian townhouses and modern cavity wall buildings all rely on mortar joints to help maintain the performance of their external walls.

However, the materials and techniques suitable for one property may be entirely wrong for another. A modern cement-rich mortar that performs well on certain contemporary bricks could damage the softer, more porous brickwork found in older buildings.

Understanding common brickwork repointing mistakes is therefore important for homeowners, builders and property developers planning restoration or exterior maintenance.

This guide explores 17 common repointing errors, their consequences, the correct techniques for avoiding them, and additional considerations for traditional British buildings.

What Is Brickwork Repointing and Why Is It Important?

Brickwork repointing involves carefully removing deteriorated mortar from the joints between bricks and replacing it with fresh, compatible mortar.

Mortar gradually deteriorates through exposure to rain, frost, temperature fluctuations, building movement and general weathering. When joints become loose or excessively recessed, water may penetrate the masonry more easily.

Proper repointing helps to:

• Reduce excessive rainwater penetration through defective joints.
• Protect vulnerable brick edges from weather damage.
• Restore the appearance of external brickwork.
• Maintain the durability of masonry walls.
• Limit draughts entering through defective solid-wall construction.
• Preserve traditional architectural detailing.
• Reduce the likelihood of more extensive masonry repairs.

Nevertheless, not every old-looking mortar joint needs replacing. Mortar can remain functional despite some surface weathering.

The Society for the Protection of Ancient Buildings (SPAB) advises against unnecessary repointing, particularly where historic mortar remains sound.

17 Common Mistakes When Repointing Brickwork

1. Using the Wrong Mortar Mix

Choosing an incompatible mortar is one of the most damaging mistakes in brickwork restoration.

Mortar must be suitable for the brick’s strength, porosity and the way the wall was originally constructed.

Modern buildings commonly incorporate cement-based mortars, while many older British properties were constructed with lime-based mortars.

Using excessively strong cement mortar on soft historic brickwork can prevent moisture from evaporating readily through the joints. Water may instead remain within the bricks, increasing the risk of frost damage and surface deterioration.

How to avoid this mistake:

• Identify the existing mortar before selecting a replacement.
• Consider the building’s age, brick type and exposure conditions.
• Use a compatible lime-based mortar where appropriate for traditional masonry.
• Avoid choosing a stronger mortar simply because it appears more durable.
• Seek specialist mortar analysis for important or complex historic buildings.

The correct mortar should work with the bricks rather than behave as a rigid barrier around them.

2. Removing Too Little Old Mortar

Shallow mortar removal can prevent new pointing from forming a durable bond.

Applying fresh mortar over a thin layer of deteriorated material may initially improve the appearance of a wall, but the repair can quickly crack or become detached.

For conventional brick joints, guidance commonly recommends removing defective mortar to a depth of approximately two and a half times the joint width, where this can be achieved safely.

For example, a joint measuring 10 mm in width may require approximately 25 mm of preparation.

However, this should not be treated as permission to excavate sound historic mortar unnecessarily. The condition of the joint, construction type and structural stability must guide the work.

How to avoid this mistake:

Remove deteriorated mortar carefully until a suitable, sound backing is reached, following conservation guidance where applicable.

3. Removing Too Much Mortar or Damaging the Bricks

Excessive mortar removal is just as problematic as insufficient preparation.

Aggressive raking can damage the edges of bricks, sometimes called arises, and weaken fragile masonry.

Older handmade bricks are particularly vulnerable because their edges may already have deteriorated through decades of weather exposure.

Damage can include:

• Chipped brick corners.
• Enlarged or uneven joints.
• Cracked brick faces.
• Loss of historic mortar.
• Disturbance of loose masonry.

How to avoid this mistake:

Use appropriately sized hand tools wherever practical, particularly on heritage buildings. Remove material gradually and avoid applying unnecessary force.

If the joints are unusually narrow, fragile or deteriorated, consult a conservation specialist before proceeding.

4. Using Angle Grinders Incorrectly

Power tools can speed up mortar removal, but careless use may create permanent damage.

An angle grinder fitted with an unsuitable blade can cut into brick edges, widen joints and leave an uneven appearance.

Mechanical removal is especially risky on Victorian and Georgian brickwork where joints may be narrow and brick faces relatively soft.

It also creates substantial quantities of potentially hazardous silica-containing dust.

The UK Health and Safety Executive identify mortar raking as a high-risk dust-producing activity. Where mechanical tools are used, appropriate extraction, respiratory protection and other controls are necessary.

How to avoid this mistake:

Choose tools according to the masonry’s condition. On historic brickwork, hand removal is generally preferable unless a competent specialist has established that another method is safe.

Never prioritise speed over the preservation of the bricks.

5. Failing to Clean the Joints Properly

Loose dust, sand and mortar fragments can interfere with the bond between existing masonry and fresh mortar.

This mistake is particularly common when the removal stage is rushed.

Even a carefully selected mortar mix may perform poorly if it is packed against dusty, unstable surfaces.

How to avoid this mistake:

After raking out the joints:

1. Remove loose material with a suitable stiff brush.
2. Clear remaining debris from the joint.
3. Inspect the backing mortar for stability.
4. Dampen the joints appropriately before pointing.
5. Avoid leaving standing water inside the joint.

Cleaning should be thorough but gentle enough to preserve vulnerable masonry.

6. Not Dampening the Brickwork Before Repointing

Dry, porous bricks can absorb moisture from fresh mortar too rapidly.

This is particularly important for older brickwork and lime-based mortars, which need suitable moisture conditions to develop strength.

If moisture is drawn away too quickly, the mortar may become weak, powdery or poorly bonded.

However, thoroughly soaking the wall immediately before pointing can cause different problems.

How to avoid this mistake:

Lightly dampen the prepared joints using an appropriate method, allowing the moisture to penetrate without leaving the surface saturated.

The amount of pre-wetting required depends on the brick’s absorbency, weather conditions and mortar type.

7. Adding Too Much Water to the Mortar Mix

Excessively wet mortar may seem easier to spread, but additional water can negatively affect its performance.

An over-wet mix is more likely to smear across brick faces, lose its intended consistency and suffer greater shrinkage during drying.

Different mortar systems require different working consistencies, so there is no single ideal water quantity for every project.

How to avoid this mistake:

Follow the mortar manufacturer’s instructions or an appropriately designed traditional mortar specification.

Add water gradually, use consistent measuring methods and mix only the quantity that can be applied within the material’s workable period.

Avoid attempting to revive mortar that has already begun setting by repeatedly adding water.

8. Choosing the Wrong Sand for Repointing

Sand influences mortar’s strength, texture, workability, colour and permeability.

Using unsuitable sand can produce inconsistent joints or a finish that looks noticeably different from the original masonry.

Very fine sand, poorly graded aggregates or materials containing harmful impurities may create performance problems.

Historic brickwork may also require particular aggregate sizes and colours to match the existing mortar.

How to avoid this mistake:

Select clean, appropriately graded sand suited to the chosen binder and joint width.

For conservation projects, examine the original mortar’s aggregate characteristics before selecting replacement materials.

A small trial mix can help determine whether the texture and colour are suitable.

9. Applying Mortar Without Compacting It Properly

Fresh mortar must be firmly packed into the prepared joint.

Simply spreading it across the front of a wall can leave hidden gaps and air pockets.

These defects may create pathways for moisture or result in sections of pointing separating from the original mortar behind them.

How to avoid this mistake:

Use a suitably sized pointing iron or other appropriate pointing tool to press mortar firmly into the joint.

Deep joints may require filling in layers, depending on the material and specification. Each layer should be properly compacted and allowed to firm as appropriate before the next is applied.

The objective is a complete, well-bonded repair rather than a superficial covering.

10. Overfilling the Joints and Smearing Mortar Over Bricks

Mortar should not be spread unnecessarily across the brick faces.

One common problem is overpainting, where the new mortar projects beyond the masonry surface or overlaps brick edges.

This can spoil the appearance of traditional brickwork and encourage moisture-related deterioration in vulnerable areas.

Mortar smears may also become difficult to remove once hardened.

How to avoid this mistake:

Keep mortar within the appropriate joint boundaries and finish it according to the existing brickwork and its exposure.

Remove accidental deposits carefully before they harden, using cleaning methods compatible with the masonry.

Avoid aggressive chemical cleaning, particularly on fragile historic bricks.

11. Choosing an Incorrect Pointing Profile

Common brickwork joint profiles