Why Are My Walls Cracking? Common Plaster Problems in UK Homes & How to Fix Them (2026 Guide)

Cracks in walls and ceilings are one of the most common issues found in UK homes. Whether you live in a period cottage in rural Hampshire, a Victorian terrace, or a modern new build, plaster cracks can appear for a range of reasons — some harmless and some signs of deeper issues.

Homeowners often type into Google:

• Why is my plaster cracking?

• What causes cracks in walls?

• How do I fix cracked plaster?

• Is cracked plaster serious?

In this detailed 2026 UK guide, we break down the most common causes of plaster cracks, how to tell whether they are minor or serious, and the best ways to repair them. If you’re based in Hampshire and dealing with cracked plaster, blown walls, sagging ceilings or movement around windows, this guide will help you understand what’s going on — and what to do next.

Why Plaster Cracks Appear in UK Homes

Plaster cracks rarely appear without a reason. Understanding the cause helps ensure the correct repair method is used, giving a long-lasting, smooth finish.

Here are the most common causes of cracked plaster in Hampshire properties.

1. Natural Settlement and Building Movement

Every property experiences some level of movement over time. New builds often settle in the first few years, while older homes can shift slightly with temperature changes, damp, and the ageing of materials.

Signs of settlement cracks:

• Fine hairline cracks above doors

• Small diagonal cracks near windows

• Thin lines along ceilings or corners

These cracks are usually harmless but unsightly — and can be repaired easily by a skilled plasterer.

2. Temperature and Humidity Changes

Hampshire’s climate naturally causes expansion and contraction in building materials. During cold months, walls contract. In warmer seasons, especially in lofts or rooms with direct sunlight, materials expand again.

This constant movement can cause:

• Hairline cracks

• Cracking around window reveals

• Ceiling joint cracks

• Seasonal crack patterns that appear and disappear

Silicone-based materials and flexible compounds help reduce cracking, but older plaster can still be affected.

3. Poor Quality or Rushed Plastering

A common reason for plaster cracking is poor workmanship. If the plaster was applied too thinly, dried too quickly, didn’t bond properly to the substrate, or was not mixed correctly, it can crack within months or even weeks.

Warning signs include:

• Long cracks that repeat across a wall

• Cracks that widen over time

• Plaster coming away when tapped (hollow sounding)

• Visible ridges or uneven thickness

Unfortunately, poor preparation is one of the leading causes of blown plaster and wall failure in UK homes.

4. Moisture and Damp Problems

Damp is a significant cause of plaster damage, especially in older Hampshire properties with solid walls. When moisture becomes trapped behind plaster, it causes the plaster to lose adhesion and eventually crack, crumble or bubble.

Common causes of moisture include:

• Leaking pipes

• Condensation

• Rising damp

• Penetrating damp

• Poor ventilation

If damp is the cause, the underlying issue must be fixed before any plastering work is carried out.

5. Structural Movement or Foundation Shifts

In rare cases, plaster cracks can indicate deeper structural movement. While most cracks are cosmetic, some require professional assessment.

Warning signs of more serious issues:

• Cracks wider than 5mm

• Rapidly widening cracks

• Step-pattern cracks in brickwork

• Cracks showing daylight through

• Doors or windows no longer closing properly

If you suspect structural movement, a qualified professional should inspect the property.

6. Vibrations and Everyday Wear

Everyday activities can contribute to cracks over time — particularly in areas close to roads or where heavy vehicles regularly pass.

Vibrations can loosen plaster joints and create hairline cracks, especially on ceilings taped with older methods.

What Are the Most Common Types of Plaster Cracks?

Understanding the type of crack helps diagnose the problem.

Hairline Cracks

These are thin, cosmetic cracks usually caused by minor movement, shrinkage or temperature changes. They are very common and easy to repair by filling and skimming.

Diagonal Cracks

Often appear around windows or door frames due to settlement. Usually not serious unless they widen or spread.

Ceiling Cracks

These can occur due to movement in joists, failed tape joints, or older lath-and-plaster ceilings giving way. Ceilings require careful inspection, as loose plaster can be dangerous.

Blown Plaster

This is where the plaster has detached from the wall behind it. It may appear cracked, hollow or bulging.

Common causes:

• Moisture damage

• Poor bonding

• Ageing materials

Blown plaster typically requires removal and replacement.

Wide Cracks

Cracks larger than 5mm may indicate:

• Significant movement

• Damp

• Structural issues

• Heavily aged plaster

These must be assessed professionally before repair.

How to Fix Cracked Plaster in UK Homes (2026 Methods)

The right repair depends on the cause and severity of the crack.

1. Filling and Skimming Hairline Cracks

Hairline cracks can usually be repaired by:

Steps:

1. Opening the crack slightly for proper bonding

2. Applying flexible filler or joint compound

3. Sanding smooth once dry

4. Skimming the area with finishing plaster

This provides a clean, invisible repair ready for painting.

2. Repairing Cracks Caused by Movement

Movement-related cracks often require stronger repair methods, such as:

Options include:

• Fibreglass mesh tape

• Joint reinforcement

• Flexible skim coats

• Re-plastering weak areas

This ensures the crack does not simply reappear after a few months.

3. Fixing Blown Plaster

When plaster becomes hollow or detached, it must be removed and replaced.

Process:

1. Removing loose or blown sections

2. Applying bonding plaster or board to rebuild the surface

3. Skimming to finish

Blown plaster cannot be patched successfully without proper removal.

4. Replacing Damaged Ceilings

If a ceiling is sagging, cracked or water damaged, it may need partial or full replacement. This typically involves:

• Removing damaged sections

• Installing new plasterboard

• Taping joints

• Skimming the entire ceiling

This restores safety and provides a clean, modern appearance.

5. Addressing Damp Before Plaster Repairs

If damp caused the crack, plastering alone won’t fix the issue. The source of moisture must be addressed:

• Repair leaks

• Improve ventilation

• Install damp-proofing where needed

• Remove salt-contaminated plaster

Once the area is dry, new plaster can be applied.

How to Tell When You Need a Plasterer in Hampshire

You should contact a professional plasterer if:

✔ Cracks keep coming back after DIY repair

✔ Walls sound hollow when tapped

✔ The crack is wider than 3–5mm

✔ There are signs of damp or mould

✔ The ceiling is cracked, bowed or uneven

✔ You’ve recently had electrical or plumbing work

✔ You’re renovating a room or doing home improvements

A good plasterer will diagnose the issue and recommend the correct repair method.

How to Prevent Plaster Cracks in the Future

✔ Maintain good ventilation

✔ Control humidity levels

✔ Fix minor cracks before they spread

✔ Avoid slamming doors

✔ Use flexible fillers on movement-prone areas

✔ Maintain gutters and roofing to prevent damp

Regular maintenance helps preserve the condition of your internal walls.

Conclusion: Cracks in Walls Are Normal — But They Shouldn’t Be Ignored

Cracked plaster is extremely common in Hampshire homes, and in many cases, the issue is cosmetic rather than structural. However, it’s important to identify the cause to ensure the right repair method is used.

Whether your walls are developing hairline cracks, your ceiling has started to sag, or you’ve noticed blown plaster, a professional plasterer can assess the problem and restore your surfaces to a smooth, lasting finish.

Need Cracked Plaster Repaired in Hampshire? Contact Murrell Bros

If you have cracks, blown plaster or damaged ceilings, the team at Murrell Bros can help. We specialise in:

✔ Plaster crack repairs

✔ Skimming and re-skimming

✔ Dry lining

✔ Ceiling repairs and replacements

✔ Full replastering

✔ Renovation and restoration plastering

We provide free, no-obligation quotes anywhere in Hampshire.

Contact Murrell Bros today for expert plastering repairs and professional advice.