Specifying floor treatments for historic buildings requires balancing conservation principles
with performance, durability, and aesthetics, says Alec Stacey
BONA has long been involved with old floors within historic buildings. From the Tower of London, Admiralty Arch and Hever Castle to Abbey Road recording studios, there’s always a degree of concern whether the proposed floor renovation will alter aspects of the performance or aesthetics.
Of course, this is understandable; but from a specifier or contractor’s perspective, what are the criteria for specifying wood flooring treatments within historic or listed buildings?
When working with listed buildings all works that may affect the ‘historic fabric’, must be considered and are subject to specific conservation principles. The historic fabric is the original, or added, building or construction materials, features and finishes that existed during the period that are deemed to be most architecturally or historically significant or both.
Key criteria for treatments are based on preservation, reversibility, compatibility, and minimal intervention. These are detailed in the British Standard BS 7913: 2013 ‘Guide to the Conservation of Historic Buildings’. This describes best practices for inspecting, managing, and maintaining traditional and historic buildings.
Whether you’re a homeowner with a Victorian terrace, a buyer considering a listed property, or a developer working on Georgian heritage assets, it’s important to have a good understanding of the conservation principles.
Minimal Intervention is of primary importance. Unlike outdated industry approaches that rely heavily on chemical treatments and invasive repairs, BS 7913 promotes a holistic, low impact approach with a focus on accurate diagnosis, sustainable methods, and preserving the character and fabric of buildings.
As much as possible of the original material should be retained with full replacement avoided if repairs are feasible.
A crucial aspect of BS 7913 is its guidance on dampness, timber decay, and insect infestation in historic buildings. The Standard directly challenges the outdated requirement often cited by mortgage valuers when they ask for a damp survey made by the Property Care Association (PCA), which has led to widespread unnecessary chemical treatments, inappropriate interventions, and permanent damage to period properties.
Instead, the document encourages intelligent, cost-effective diagnosis – emphasising issues like ground levels, ventilation, and moisture control. In most cases chemical treatment is unnecessary.
BS 7913 provides practical guidance on how to assess moisture and water ingress. Timber decay is typically moisture related. Providing the moisture content of the wood remains below 20% fungal activity will cease without the need for chemicals. Damp can also relate to other issues such as poor drainage or ventilation rather than rising damp from the subfloor/walls etc.
BS 7913 also addresses the ecological impact of indiscriminate chemical spraying, such as in bat-inhabited roof spaces, where toxic treatments can be illegal without a license. This is especially relevant for developers who may unknowingly breach wildlife protection laws. Insecticidal treatment should be a last resort, and only when absolutely necessary and ‘precautionary treatment should not be applied to unaffected timbers.’
Along with avoiding unnecessary chemicals, any treatments, stains, or remedial processes should be reversible, or at least not hinder any future conservation work. Treatments must also be compatible with the existing wood in the case of flooring. In some cases there will be a reluctance to introduce radically different treatments, for example moving from a breathable coating to one that seals the timber completely, which may trap moisture and lead to fungal decay.
For this ‘breathability’ and moisture control, traditional finishes, such as penetrating oil, are often favoured over less permeable surface coatings. It is important also to preserve the natural patina and historic appearance of the flooring where possible in addition to employing a sympathetic cleaning and maintenance regime.
Sometimes for practical reasons a wood floor will need to be completely resanded and retreated. Perhaps the flooring is in such a condition that only sanding can return it to use. Consent may be required if the finish affects the character of the building (Listed Building Consent) from your local planning authority. This would be accompanied with a Heritage Statement, describing the nature of any changes and the justification. One must also consider the specific grades of listed buildings.
Grade I listed buildings are considered to be of exceptional and international significance and subject to a very high level of scrutiny. All changes, even minor treatments to floors, require consent and usually consultation with officers of Historic England. Grade II are deemed particularly important buildings of more than special interest. Here there are significant restrictions and treatments must be carefully justified. This may require detailed method statements and conservation reports. Grade II buildings are those of special interest warranting preservation efforts. There is greater flexibility but consent is still required if changing the character of the floor eg sanding, floor replacement, staining etc.
Ultimately, the success of any flooring specification in historic buildings will involve a treatment and associated maintenance regime which allows the floor to meet the level of trafficking and general use it is put to.
To preserve the floor future sanding should be avoided. This is possible by selecting treatments like penetrating oil, which require re-oiling, a process possible without resanding. Alternatively, a durable coating can be used, to provide a more practical, easier to clean surface.
Success here will be determined by achieving the correct frequency for recoating the floor. This will prevent wear from progressing back to bare wood and negate the need for resanding the floor back to bare wood. Between recoating, effective maintenance will keep the floor in top form, retaining slip resistance and other important considerations.
01908 525150
info.uk@bona.com
www.bona.com
Alec Stacey is technical manager at Bona