Historic Floors, Tiles and Terracotta: Conservation, Repair and Cleaning

A conservation guide to the floors of historic buildings: timber boards, stone flags, brick and pamments, encaustic and geometric tiles, terracotta and lime floors. It covers how they were built, why they fail, how to clean and repair them, and how to avoid the common mistakes that destroy them.

Building Restoration Index — Technical Library. By Paul Stenning and Mike Walters, Historic Buildings Advisors, Tuscan Foundry Products.

Types of historic floor

The material and construction of a floor tell you a great deal about the building’s date, status and use.

• Earth and lime floors. Rammed earth, lime ash and gypsum floors were common in vernacular buildings and upper floors in some regions. They are now rare and often significant.
• Stone flags. Local flagstones such as sandstone, limestone and slate laid on earth, sand or lime, typical of kitchens, halls and ground floors.
• Brick and pamments. Floor bricks and square clay pamments laid on sand or lime, common in service areas, dairies and East Anglian buildings.
• Timber floors. Boards on joists, from wide oak or elm boards in early buildings to narrower softwood boards in Georgian and Victorian houses. Ground floors were often suspended over a ventilated void.
• Encaustic and geometric tiles. Victorian and Edwardian tiled floors in halls, porches, churches and public buildings, made by firms such as Minton. Encaustic tiles have the pattern inlaid through the clay; geometric tiles are plain-coloured shapes laid in patterns.
• Terracotta and quarry tiles. Unglazed clay tiles, hard-wearing and often laid in kitchens, conservatories and passages.
• Marble, terrazzo and mosaic. Found in grander halls, churches and commercial buildings.

How solid floors manage moisture

Traditional solid floors were laid directly on the ground without damp-proof membranes, and they rely on moisture evaporating from their surface.

Ground moisture rises into the floor and evaporates into the room. As long as this can happen, the floor and the walls around it stay in balance. The floor may feel cool and occasionally damp, but the building is not harmed.

If the floor is sealed with an impermeable sealer, covered with vinyl or rubber-backed carpet, or replaced with concrete and a membrane, the moisture has to go somewhere else. It moves sideways into the base of the walls, causing rising damp, salt damage and decay of skirtings and plaster. See our guide to damp in historic buildings.

Timber floors

Historic timber floors can usually be repaired board by board, keeping their character and patina.

• Ventilation. Suspended ground floors need a ventilated void below. Keep airbricks clear and working, and replace broken ones with matching cast iron or clay airbricks. Blocked ventilation leads to rot and beetle attack.
• Loose and squeaking boards. Refix with screws or traditional cut nails into the joists, keeping the original boards.
• Damaged boards. Piece in new timber or reuse sound boards from elsewhere, matching species, width and thickness. Avoid replacing whole floors when only a few boards are damaged.
• Gaps. Fill wide gaps with thin timber slips glued to one board only, so the floor can still move.
• Joists. Check joist ends built into damp walls for rot. Repair rather than replace where possible, and find out why the timber got wet.
• Finishes. Many historic floors were scrubbed, waxed, oiled or painted. Avoid sanding off old surfaces and patina; gentle cleaning and wax are usually better than heavy sanding and modern lacquers.

Lifting boards for services should be done carefully, numbering each board and keeping it for relaying. Our guide to historic timber frames covers timber decay in more detail.

Stone, brick and earth floors

Stone, brick and earth floors are tolerant of moisture, as long as they are not sealed or replaced with impermeable materials.

• Uneven and rocking flags. Lift, rebed on lime or a breathable bed and relay in the same position. Number and record each flag first.
• Cracked flags. Many cracked flags remain serviceable. Replace only those that are unsafe, with matching reclaimed or new stone of the same type.
• Brick and pamment floors. Relay loose units on sand or lime. Match replacements in size, colour and texture.
• Earth and lime ash floors. These are fragile and need specialist repair with matching materials. Avoid heavy loads and wet cleaning.
• Relaying a solid floor. Where a floor must be lifted, a breathable insulated limecrete base can be an option, but the original floor may be significant in its own right and should be relaid on top rather than replaced.

Encaustic and geometric tiled floors

Victorian and Edwardian tiled floors are robust, but they suffer from failed bedding, movement in the sub-floor and harsh cleaning.

• Loose tiles. Often caused by failure of the original lime or sand and cement bed. Lift loose tiles carefully, clean off old bedding, and refix on a suitable bed in the same position.
• Cracked and missing tiles. Replace with reclaimed tiles or reproductions matched in size, thickness, colour and pattern. Several manufacturers make reproduction encaustic and geometric tiles. Keep any original tiles that are only cracked, if they are stable.
• Sunken areas. Usually a sign of a failing sub-floor, which needs investigation before relaying.
• Tiles under later coverings. Original floors are often found under carpet, lino or hardboard. Remove adhesives with care; some old adhesives and underlays may contain asbestos and need testing first.
• Record before lifting. Photograph and draw the pattern before taking up any area, and number the tiles.

Terracotta, quarry tiles and mosaic

Unglazed clay floors are porous and easily stained, but hard-wearing if they are maintained properly.

• Terracotta and quarry tiles were traditionally finished with oils and waxes. Modern impermeable sealers can trap moisture and salts and cause flaking.
• White salt deposits are common on newly cleaned or relaid clay floors as moisture evaporates. Brush them off dry and allow the floor to dry out before applying any finish.
• Mosaic and terrazzo floors need specialist repair to match the stones and the setting.

Cleaning historic floors

More historic floors are damaged by cleaning than by wear.

• Start with the gentlest method: dry sweeping or vacuuming, then clean water with a pH-neutral cleaner and a soft brush, removing the water promptly.
• Never use acid-based cleaners, brick cleaners or descalers on limestone, marble, terracotta or encaustic tiles. They dissolve the surface and the colour.
• Avoid pressure washers, steam cleaners and heavy abrasive machines, which erode surfaces and drive water into the bedding.
• Test any cleaning product on a small, hidden area first.
• Remove old wax and sealer layers only with methods recommended by a floor conservator.
• Use doormats at entrances to cut down grit, which is the main cause of wear.

Finishes and sealers

The finish on a historic floor should protect it without trapping moisture.

• Breathable waxes and oils suit timber, terracotta and some stone floors, and can be renewed.
• Impermeable sealers, varnishes and polyurethane coatings can trap ground moisture in solid floors, causing whitening, flaking and salt damage. They are also hard to remove.
• Where a sealer is needed, choose one that is vapour-permeable and test it first.
• Rugs on solid floors should have breathable backings. Rubber-backed mats and rugs trap moisture and stain floors.

Underfloor heating and services

Installing underfloor heating or new services usually means lifting historic floors, and the damage can outweigh the benefits.

• Lifting and relaying stone flags, tiles and boards risks breakage and loss of the original arrangement.
• New concrete screeds and membranes for underfloor heating change how the floor handles moisture.
• Radiators or other heat emitters are often a less harmful choice in historic buildings. See our guide to energy efficiency and heating in historic buildings.
• Where services must cross a floor, use existing routes and lift the minimum.

Archaeology under floors

Floors in older buildings, and especially in churches, often sit over earlier floors, burials, foundations and archaeological deposits.

Lifting and excavating floors can destroy evidence of the building’s history. In churches, floors may cover burial vaults and ledger stones. An archaeological watching brief or assessment may be needed before work, and is often a condition of consent.

Consent and recording

On a listed building, the floors are part of the listing, whether or not the list description mentions them.

• Like-for-like repair of small areas may not need consent, but lifting, relaying, replacing or covering historic floors usually does. See our guide to Listed Building Consent.
• Record the floor with photographs and drawings before work.
• Keep surplus original tiles, flags and boards on site for future repairs.
• In churches, floors are covered by the denomination’s own permission system.

Choosing specialists

Floor repair is skilled work, and different floors need different trades.

• Historic tile and terracotta specialists for encaustic, geometric and quarry floors.
• Joiners and timber flooring specialists for boarded floors.
• Masons for stone flags and marble.
• Floor conservators for significant or fragile floors, including earth, lime ash and mosaic.
• A surveyor or architect to investigate damp, sub-floor problems and ventilation.

Ask for examples of similar work and check references.

Common mistakes

Mistake	Consequence
Replacing a solid floor with concrete and a damp-proof membrane	Ground moisture driven into the walls, and loss of historic flooring
Sealing stone, brick or clay floors with impermeable sealers	Trapped moisture, salt damage, whitening and flaking
Using acid cleaners on limestone, marble, terracotta or encaustic tiles	Etched, dulled and discoloured surfaces
Blocking airbricks under suspended timber floors	Rot and beetle attack in joists and boards
Sanding historic boards back to bare wood	Loss of thickness, patina and evidence of earlier finishes
Lifting tiles or flags without recording them	Patterns and arrangements lost when relaying
Rubber-backed mats and rugs on solid floors	Trapped moisture and stained floors
Removing old adhesives without testing for asbestos	Health risk to occupants and workers
Replacing whole floors when only a few areas are damaged	Unnecessary loss of original fabric
Installing underfloor heating under historic floors	Breakage of original material and changes to moisture behaviour

Find a specialist

Specialists in the Building Restoration Index who work on historic floors, grouped by the part they play in a project:

Contractors and craftspeople

• Flooring — historic floor repair, relaying and conservation
• Timber Flooring — repair and supply of historic boarded floors
• Stone and Stonework — stone flags, marble and stone repair
• Fine Joinery — board repairs, slips and joinery
• Damp and Timber Decay — investigation and treatment of decay in floor timbers

Architects, surveyors and engineers

• Surveyors — damp, ventilation and sub-floor investigations
• Architects — consent and specification for floor works
• Structural Engineers — failing joists and sub-floor structures

Consultants and designers

• Heritage Consultants — significance of historic floors
• Archaeologists — watching briefs where floors are lifted

Investigation and recording

• Materials Analysts — analysis of tiles, mortars, salts and moisture
• Non-Destructive Investigations — surveys of voids and moisture

Material suppliers

• Tiles — reproduction and reclaimed encaustic, geometric and quarry tiles
• Terracotta — terracotta tiles and clay products
• Architectural Salvage — reclaimed flags, boards, bricks and tiles
• Stone — matching stone for flags and repairs
• Lime Mortars & Plasters — lime for bedding and limecrete floors

Advice and training

• Organisations — national amenity societies and trade bodies, including those that publish technical advice
• Courses, Training & Events — courses and events for owners, contractors and professionals

Further reading from Tuscan Foundry

• Breathing walls: cast iron airbricks and free airflow
• Cast iron airbricks and vents from Tuscan Foundry

Related guides

• Damp in historic buildings
• Historic timber frames
• Energy efficiency and heating in historic buildings
• All guides in the Technical Library

The Index lists specialists without endorsement; check experience, references and insurance before appointing anyone. Specialists can add a free listing.

Frequently asked questions

Should I put a damp-proof membrane under an old stone floor?

Usually not. Traditional solid floors rely on moisture evaporating from their surface. A membrane or concrete slab pushes ground moisture into the walls instead, causing damp at their base. A breathable floor is generally the better approach.

How do I clean Victorian encaustic tiles?

Sweep or vacuum first, then wash with clean water and a pH-neutral cleaner, removing the water quickly. Never use acid cleaners, which etch the surface and fade the colours. Test products on a hidden area first.

Can loose Victorian floor tiles be refixed?

Yes. Lift them carefully, clean off the old bedding and refix them in the same position on a suitable bed. Record and number them first. Sunken areas suggest a sub-floor problem that should be investigated.

Where can I get replacement encaustic tiles?

Reclaimed tiles from salvage dealers, or reproduction tiles made to match size, thickness, colour and pattern. Several manufacturers make reproduction encaustic and geometric tiles.

Should I sand my old floorboards?

Avoid heavy sanding where possible. It removes thickness, patina and evidence of earlier finishes. Gentle cleaning, repair and wax are often better. If sanding is necessary, do the minimum.

Why is there white powder on my terracotta floor?

Usually soluble salts carried to the surface as the floor dries out. Brush them off dry and let the floor dry thoroughly before applying any finish. Wet cleaning will only bring more salts up.

Can I seal a flagstone floor?

Avoid impermeable sealers, which trap moisture and cause flaking and salt damage. If protection is needed, use a breathable wax or a vapour-permeable product, tested on a small area first.

Why are my floor joists rotting?

Usually because the void under a suspended floor is not ventilated or the joist ends are built into damp walls. Clear and replace airbricks, find the source of damp, and repair the timber.

Can I put underfloor heating under a historic floor?

It usually means lifting and relaying the floor and adding new screeds, which risks breakage and changes how the floor handles moisture. Radiators are often less harmful in historic buildings.

Do I need Listed Building Consent to replace a floor?

Usually yes. Floors are part of a listed building even if the list description doesn’t mention them. Lifting, replacing or covering historic floors normally needs consent; small like-for-like repairs may not.

Is it safe to remove old floor adhesive?

Test it first. Some old adhesives, tiles and underlays contain asbestos. Have samples tested before scraping, sanding or grinding.

What is a limecrete floor?

A floor base made with lime and a lightweight aggregate, often with insulation, that lets moisture pass through rather than trapping it. It is sometimes used when an old solid floor has to be relaid.

Should cracked flagstones be replaced?

Not if they are stable and safe. Cracks are part of the floor’s history. Replace only flags that are broken up or a trip hazard, with matching stone.

How do airbricks protect timber floors?

They let air flow through the void under a suspended floor, carrying moisture away from joists and boards. Blocked or missing airbricks are one of the main causes of floor timber decay.