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Historic Brickwork Survey: Cracks, Spalling, Salts and Incompatible Pointing
Historic brickwork records how a building was made, altered and weathered. Bricks, bonds, mortar joints, tuck pointing, rubbed arches and traces of earlier openings can all contribute to significance. When deterioration appears, the objective is not to make every elevation look new. It is to understand why the fabric is failing and retain as much sound material as possible.
Cracks, crumbling faces and white salts are symptoms with several possible causes. Repointing alone may not address leaking rainwater goods, trapped moisture, corroding ironwork or movement. Inappropriate cutting-out can also damage the brick edges that a repair was intended to protect. A historic brickwork survey provides the evidence for a proportionate specification.
Read the wall before specifying the repair
The first task is to understand construction. Hand-made and machine-made bricks vary in strength, porosity, firing and dimensions. Mortars may be lime, earth, natural cement or later Portland cement. Solid walls behave differently from cavity walls, and decorative elevations may use fine jointing or gauged work that requires specialist knowledge.
A survey records brick type, bond, joint profile, mortar condition, wall thickness where known, openings, embedded metalwork, alterations and exposure. It should distinguish original or early fabric from later repair. That context determines whether a defect is local weathering, a material-compatibility problem or evidence of wider movement.
Historic England guidance on repairing older walls recommends advice from professionals experienced in older masonry and the use of appropriate repair materials. The SPAB guide to repairing old brick walls likewise stresses conservative repair with traditional materials.
Spalling and surface loss identified during a historic brickwork survey
Spalling describes brick faces flaking, breaking or crumbling away. It is often associated with moisture, frost action and salts. The visible loss may be concentrated at parapets, chimneys, plinths, below leaking gutters or beside hard cement repairs.
Historic England’s guidance on masonry buildings explains how moisture and salts can damage brick or stone, particularly where impermeable coatings or cement-rich mortar restrict drying. Freeze-thaw action can then disrupt saturated porous faces.
The survey should establish whether the moisture source is active. Defective copings, open joints, blocked gutters, raised ground, splashback and failed window details may be more important than the damaged brick itself. Replacing bricks without correcting these conditions can repeat the cycle.
Not every spalled brick needs replacement. A shallow weathered face may remain serviceable, while severe section loss at an arch, pier or loadbearing area may need carefully matched repair. Options can include monitoring, local mortar repair, selective brick replacement or specialist surface repair. The chosen approach should minimise loss of historic fabric and avoid creating a harder, less permeable patch.
Salts and moisture movement
White deposits are often described simply as salts, but their appearance and location need interpretation. Efflorescence forms when soluble salts travel with moisture and crystallise at the surface. Crystallisation within the pores, sometimes called subflorescence or cryptoflorescence, can be more damaging because pressure develops below the surface.
Possible salt sources include the original materials, ground moisture, previous agricultural use, combustion products, contaminated water and inappropriate treatments. Sampling and laboratory analysis may be justified where the result will change the repair or conservation strategy.
Dense paint, water repellents and impermeable internal finishes can alter drying. Our article on breathability in conservation explains why vapour permeability alone does not describe the whole moisture behaviour of traditional construction.
Cracks: movement, decay or local stress
Cracks should be recorded by position, direction, width, displacement and relationship to openings or structural features. Stepped cracking may follow mortar joints, vertical cracks may occur at junctions, and local fractures above windows can relate to lintels or arches. Corroding embedded iron can expand and split surrounding masonry.
The pattern does not diagnose the cause by itself. Surveyors consider foundation conditions, drainage, roof spread, wall restraint, thermal movement, previous alterations and the chronology of repairs. Historic buildings often contain longstanding distortion that is stable. Fresh edges, debris, sticking openings or progressive change may justify monitoring or advice from a conservation-experienced structural engineer.
Crack stitching is not an automatic solution. It can be appropriate for a defined defect, but inserting bars without understanding movement may transfer stress or obscure evidence. The cause, structural function and significance should be established first.
Why hard cement pointing can be damaging
Traditional lime mortar is commonly softer and more permeable than the bricks it surrounds. It accommodates small movements and acts as a sacrificial joint that can be maintained. Hard cement-rich pointing may concentrate evaporation, salt crystallisation and frost damage in the softer brick faces instead.
SPAB guidance on inappropriate cement pointing warns that impervious pointing can cause erosion of bricks and stones. That does not mean every cement joint should be aggressively removed. Where it is strongly bonded, cutting it out may damage the surrounding arrises. Trial panels and a cautious removal method are often appropriate.
The replacement mortar must be designed for the wall, exposure and original materials. “Lime mortar” is not one universal product. Binder, aggregate, grading, colour, strength, workability and curing all matter. The joint profile should follow evidence rather than a modern fashion.
Survey and specification sequence
A proportionate brickwork investigation may include:
measured and photographic defect mapping;
inspection of roofs, copings, flashings and rainwater goods above affected areas;
assessment of ground levels, drainage and splashback;
close inspection of bricks, mortar joints and previous repairs;
identification of wall movement and structural relationships;
review of historic photographs, listing information and past specifications;
limited mortar or salt sampling where results will inform the repair;
trial panels for cleaning, cutting-out, mortar colour and joint finish;
recommendations for monitoring, access and specialist input.
The report should separate urgent safety work from maintenance and longer-term conservation. Loose masonry over a public route may require immediate risk management. Repointing a weathered but stable rear wall may be planned in phases. Moisture sources should be addressed before decorative finishes are reinstated.
Cleaning, coatings and previous repairs
Cleaning can remove soiling, paint or biological growth, but it can also erode fired brick surfaces and mortar. The least aggressive effective method should be selected after trials. Abrasive blasting and uncontrolled pressure washing can permanently damage historic masonry.
Water-repellent treatments require particular caution. They may alter appearance and moisture movement, and future maintenance can be difficult. A coating should not be used to compensate for defective pointing, copings or rainwater disposal.
Previous brick replacement also needs review. A visually similar brick may be too hard, too impermeable or dimensionally unsuitable. Reclaimed bricks can be valuable, but their condition, source and compatibility need checking. Repairs should match performance as well as colour.
Consent in England and Wales
For a listed building in England, works that affect its special architectural or historic interest require listed building consent. Localised genuinely like-for-like maintenance may fall outside that requirement, but wholesale repointing, a changed joint profile, extensive brick replacement, coatings or aggressive cleaning can affect character. Seek written advice from the local planning authority before committing to the specification.
In Wales, Cadw’s listed building consent guidance similarly explains that even relatively minor work can require consent where special interest is affected. The local planning authority administers applications, with Cadw involved as required by the Welsh system. Do not assume that work described as “repair” is automatically exempt.
AMS SURVEYS can link the condition evidence to listed building consent advice and the drawings or heritage information needed for a proposed repair.
Frequently asked questions
Why do old bricks spall?
Spalling usually involves moisture within porous brickwork combined with frost, salts, incompatible coatings or hard impermeable mortar. The survey should identify the moisture source and material relationship before bricks are replaced, because treating only the damaged face may allow deterioration to continue.
Should all old mortar joints be repointed?
No. Sound historic mortar should normally be retained. Unnecessary cutting-out can damage brick arrises and remove evidence of the building’s construction. Repointing should be limited to genuinely defective joints and use a compatible mortar and joint profile.
Are cracks in historic brickwork always structural?
No. Cracks may arise from thermal or moisture movement, corroding metal, local decay, foundation movement, altered openings or structural failure. Pattern, width, direction, history and related distortion must be considered before deciding whether monitoring or structural advice is needed.
Does repointing a listed building need consent?
Like-for-like local repair may not require listed building consent, but changing the mortar, joint profile, extent or appearance can affect special interest. In England, seek advice from the local planning authority; in Wales, consult the local planning authority and Cadw guidance before work starts.
Protect the fabric before choosing the finish
AMS SURVEYS undertakes historic building surveys and focused heritage defect investigations across England and Wales, with strong coverage throughout Liverpool, Manchester, Cheshire, Lancashire, North Wales, Leeds, Sheffield, Stoke and the wider North. Send us photographs, the listing entry and any previous repair documents. We can scope the inspection, establish priorities and provide a defensible basis for conservation repairs.
