Plaster Pathology, Cracks & Moisture: Diagnosis & Causes

Deteriorated plaster wall with cracks, salt and peeling

Every crack, stain or peel on your wall tells a story. The secret to permanent repair isn't surface-level filling, but correctly diagnosing the root cause.

In this section, we analyse plaster "pathology": from harmless hairline cracks and unsightly salt deposits to destructive rising damp and dangerous structural failures. Learn to decode wall symptoms and protect your building before problems spread.

Crack Analysis & Types

Not all cracks are the same. Some are merely cosmetic blemishes while others signal structural or insulation problems. Learn to distinguish crack types and their real causes.

Shrinkage Cracks (Drying)

The most common issue in new renders. Why a bad mix, excessive heat and rapid drying crack the surface like a spider web.

Structural Cracks in Plaster

When to worry. How to distinguish cracks from ground settlement, earthquakes or poor masonry-to-concrete connections.

Plaster crack types: hairline, structural, shrinkage

Thermal Cracks (Expansion - Contraction)

The building's reaction to temperature changes. How sudden weather shifts create stresses that crack external facades.

ETICS Cracks (Thermal Insulation)

When the insulation system fails. Common causes: poor mesh embedment, missing corner beads and base coat errors.

Hairline Cracks (Micro-Cracks)

Harmless or dangerous? Identification guide for cracks under 1mm wide and how they affect your home's waterproofing.

Moisture, Salts & Mould

Water is the number one enemy of every building. Whether from the ground, rain or interior humidity, moisture gradually erodes plaster finishes.

Rising (Capillary) Damp

The "sponge" effect. How water rising from foundations destroys low-level plaster, causing severe deterioration.

Salt Efflorescence on Plaster

Those annoying white patches. Where salts come from, how they destroy paint and why simple washing won't remove them.

Interior wall with rising damp, salt deposits and mould

Moisture Behind Plaster

The invisible threat. How hidden plumbing leaks and poor joint sealing trap water, rotting masonry from inside out.

Interior Plaster Mould

A health and aesthetics issue. The role of condensation, poor ventilation and how thermal bridges create the perfect environment for fungi.

Weathering & Ageing (UV & Climate)

Time leaves its marks. Surface deterioration, fading and strength loss caused by solar radiation and acid rain.

Delamination, Blistering & Hollow Plaster

When plaster loses contact with the wall, collapse is only a matter of time. Learn to spot dangerous areas before accidents from falling material occur.

Plaster Delamination from Substrate

Why adhesion fails? The role of poor preparation, missing primer and dust that prevents bonding to the wall.

Plaster Blistering

When the wall forms "bubbles". How trapped moisture seeking escape presses the finish coat, destroying cohesion.

Plaster delamination, blistering and hollow areas

Detecting Hollow Plaster (Tap Test)

The sound test. How to locate internally delaminated areas with a light tap before complete collapse occurs.

ETICS Board Delamination

An expensive and dangerous error. Why poor adhesive application or missing mechanical fixings can cause entire ETICS sections to fall.

Frost Damage (Crystallisation)

The destructive power of ice. How trapped pore water expands in winter, "shattering" the external render layers.

Full plaster guide

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