Home health check
Bearing the wear and tear from the footsteps of generations, old stone floors are an important feature of character, so follow this advice on how to restore, maintain and repair them
Roger Hunt advises on how to protect and repair stone floors
Polished smooth and gently undulating from the passage of many feet, old stone floors are ingrained with a sense of permanence and history unmatched by any other flooring material. The flagstones and tiles forming these floors were frequently cleaved from locally quarried sandstone, limestone, slate and granite. Stone floors were traditionally laid on bare earth or chalk and, although sometimes dressed so the edges were square, the thickness of the stone often varied greatly. Imposing floors were created in the Georgian period using imported marble.
Despite the seeming solidity of the material, stone floors are vulnerable to damage, and all that makes them wonderful is easily destroyed through overzealous cleaning or attempts at relaying.
The priority is to retain old stone floors in situ, wherever possible, and to undertake appropriate maintenance and repair to preserve their charm.
Grit and dirt trodden into the surface of a floor causes significant damage, so install good doormats at external entrances. Cleaning should be approached with caution and the stone should never be soaked, as even clean water may cause damage. If required, employ a detergent, such as mild washing-up liquid diluted in hot water, and scrub gently with a stiff bristle brush, rinsing regularly but sparingly. Before using any cleaning product test it on an inconspicuous corner as some stones are easily damaged. Where white salt efflorescence is present, it is not generally a cause for concern, but washing with water exacerbates the problem; instead vacuum it off.
If significant staining or ingrained dirt is evident consider specialist stone cleaning products. Avoid abrasives, such as wire brushes and grit blasting, which will quickly damage the stone’s surface. Always seek specialist advice when in doubt.
Be wary of applying sealants and polishes. A light coat of beeswax and turpentine, along with some proprietary products, may be suitable but will invariably change the look of the stone and can restrict the floor’s ability to breathe.
Cracking and unevenness is not unusual with old stone floors and frequently results from historic settlement as well as natural wear and tear. Where ➤
problems are suspected they may be caused by voids beneath the floor or relate to other structural issues within the house, so should be fully investigated. Where necessary, a structural engineer or surveyor experienced in working with old buildings should be consulted.
Any loose or wobbling stones must be reset before they are damaged. Cracks can be repaired with lime mortar if necessary. Where stones are severely worn it’s occasionally possible to turn them over. Lifting stone slabs requires great care to avoid cracking, and there is a danger of breaking the edges of surrounding stones when levering against them. It is sometimes possible to fill voids beneath flagstones without lifting them by injecting a weak, lime-based grout or slurry, but use water sparingly. With many stone floors, the joints are left unpointed, helping breathability. Where pointing is present but has failed, rake out and repoint with lime mortar.
Stone floors were part of the breathable fabric of old buildings. Damp problems frequently occur when moisture is trapped due to changes made to the floor or within the house as a whole. In all cases, it’s essential to deal with the problem rather than the symptoms. Lifting and relaying an old floor and installing a damp-proof membrane is frequently disastrous, especially when in conjunction with the introduction of a concrete slab, as moisture is simply pushed elsewhere.
Often damp is caused by leaking water pipes and cracked or blocked drains, as well as raised external ground levels higher than the floor. Another frequent cause of problems is the use of inappropriate modern materials, including cement mortars used for pointing or repairs, rather than lime-based products.
Some problems are due to condensation on the surface of the floor, so ensure the room is well ventilated and maintain some heating. Moisture will be trapped by vinyl and synthetic or rubberbacked rugs, resulting in sweating between the floor and the rug; this is likely to mark the surface and may lead to its deterioration.
Lifting and relaying
An old floor should never be lifted without good reason as its original character will be destroyed. Where relaying is unavoidable, number each flag or tile with chalk so that they can be laid back in position, and always draw a plan or take photographs before lifting. When excavating the floor, the building’s foundations must not be undermined. Laying stone floors takes skill and is often best left to a professional.
● Regularly sweep or vacuum floors and entrance mats.
● Fit pads under metal objects to prevent any rust marks.
● Wipe up spills promptly; red wine is particularly damaging to stone floors.
● Check loose, cracked or damaged stones.
● Replace defective pointing.
● Rectify damp problems.
Fit for the future
Adding thermal insulation without disturbing a stone floor is difficult. Breathable floor coverings, such as coir rugs, can help and will also smooth out unevenness. Where an original floor, or one laid on a concrete slab, has to be relayed because of damp or other problems, a limecrete subfloor is a good option. Composed of lime and aggregate, this material enables the creation of a floor slab that can breathe, while allowing the floor’s makeup to include a high level of insulation and, where necessary, underfloor heating.
Above: Moisture can get trapped under rubberbacked or synthetic rugs, so use only breathable floor coveringsBelow: Take care when cleaning stone flags; don’t soak with water, and scrub them gently with a bristle brush