26 Sep Preserving History: English Heritage Approved Stone and Masonry Cleaning Techniques
There’s plenty of attraction in owning a historic property, but its stonework or masonry is likely to need periodic cleaning. If the building is listed or in a conservation area, this means legal restrictions on the techniques you can use. Even if this isn’t the case, though, using the wrong cleaning techniques could ruin the historic nature of the building.
English Heritage and Cleaning Historic Buildings
The English Heritage Trust is a charitable trust, originally set up by the government, whose task is to look after buildings and monuments of historical significance. Their activities range from managing major monuments, such as Stonehenge, to running the Blue Plaque scheme.
Any building that goes back for centuries is likely to need periodic cleaning. This might be due to growths such as algae, moss and lichens, or pollution from soot, industrial pollutants or limescale, but it might simply be from weathering over its lifetime.
Whether the property is made from historical materials that require special techniques, or whether its stone or masonry is simply delicate, only certain cleaning techniques are going to be safe. Fortunately, English Heritage has extensive experience with this, so you can’t go wrong by following their recommendations.
English Heritage Approved Techniques
In general, the techniques approved by English Heritage for cleaning historical stone and masonry are those using pressured water. While some chemical cleaners are suitable, many are too acidic to be used safely.
Water cleaning can be done at high or low pressure, but English Heritage only recommends low pressure for old materials. However, even low-pressure washing is effective for removing surface dirt and for cleaning away water-soluble salts and biological deposits.
Even more effective, however, is the TORC system. Recommended by English Heritage, this mixes low volumes of water with air and fine inert granulate to create a gentle, swirling vortex. The TORC system can be extremely effective at removing limescale carbon sulphation and paints that have turned brittle.
Find a Contractor Who Knows What They’re Doing
Your historic property is both a valuable investment for you and a piece of history you’re holding in trust for the future. A contractor who doesn’t understand the needs of older materials could do irreparable damage.
Your contractor should do a thorough assessment of the materials before taking any action, to determine what will be most suitable. Before hiring a contractor, check how many historic properties they’ve cleaned, as well as whether they offer English Heritage-approved techniques as standard. The last thing you want is someone who’s hired in a system they don’t have any experience using.
Give U&M a call to find out how we can clean your historic building in a way that would get the thumbs-up from English Heritage.