Our British heritage is something to be proud of. Thousands of people each year flock to the 300 or so National Trust historic buildings alone. And the upkeep for such buildings is phenomenal. Not only does cleaning of the inside take extreme care and specialist cleaning products to ensure no damage is caused to the interior surfaces and artefacts. But have you ever thought about how the outside of these buildings are cleaned? Moss, algae, ivy, extreme weather conditions and other natural substances and environmental pollution all add to the gradual decay of the stonework, roofing, and structure. But bird damage to historic buildings is extensive too.
Aside from looking unpleasant, bird droppings contain acids which, if left uncleaned, will gradually start to contaminate, and corrode, the exterior surfaces. Without regular maintenance, and careful cleaning, this could result in thousands of pounds of damage to these treasured landmark sites.
What damage do birds cause to historic buildings?
The extent of bird damage to historic buildings might not always be fully appreciated at first glance.
Continued pecking at moss, algae and salt deposits eventually disturbs protective surfaces of rocks, stone, and other construction materials, damaging the seal as well as the joints. But also corrosive effects from the acidic bird fouling continue well after the surface has been contaminated, even if the offending droppings, feathers, and stains have been cleaned away.
Feral pigeons and herring gulls are known to be the worst culprits, accounting for around 99% of bird control problems on buildings. Perhaps unsurprisingly then, the Wildlife and Countryside Act 1981 classes them in the ‘pest bird’ category, deeming them as exempt from protection.
Research has revealed that feral pigeons can carry 60 diseases, seven of which can be transferred to humans. But it is the fungi which lives on pigeon droppings that causes the most damage and decay to our historic buildings, rather than the actual bird droppings.
And it’s not just the surface of the stone that is damaged. The ‘roots’ of the fungi enter the stone, carrying naturally produced acids, strong enough to dissolve softer stone, which forms soluble salts. As this continues, the stone gradually allows more water to seep in as it becomes more porous. During colder weather, this water freezes, expands, and therefore weakens the stone further.
Additionally, the soluble salts are also dissolved and absorbed into the stonework, re-crystallising where they evaporate. This shows as ‘efflorescence,’ or what looks like a powdery substance, on the surface. And if crystallisation forms beneath the surface, more pressure is created as the crystal grows. Over time, the stone starts to crumble, and the structure deteriorates.
As for herring gulls and how they cause bird damage to historic buildings, they flock together in large groups, but nest in smaller groups. This means, although they’re very territorial, instead of one larger nesting area there could be several smaller affected areas on our heritage sites, therefore spreading the mess across a wider space.
They don’t carry the same risk of disease as pigeons, but still leave their droppings in and around their nests, staining and damaging the surrounding stonework. As with pigeon droppings, if the debris caused by herring gulls is not cleared up, and the area regularly maintained, it worsens over time. This is intensified even more as herring gulls tend to return to the same nesting area year after year.
How can bird damage to historic buildings be cleaned?
Different surfaces require differing products and techniques because of their resistance to cleaning. Softer stone such as marble, and limestone or sandstone buildings are the most affected by the acids from bird droppings and its long-lasting effects. Whereas other structures and more hardwearing stone can be cleaned with more universal products and methods. And stones which are porous should be cleaned and maintained using less water, to avoid unnecessary damage.
So, with all exterior cleaning, but even more so with cleaning bird debris and damage from historic and listed buildings, it is essential that professional and specialist cleaning companies are brought in.
It’s far from a simple case of blasting the stone, roof areas, and surrounding pathways to remove the algae, moss, and bird mess. In fact, that could damage the building and surfaces around it irreparably.
It is important therefore to assess each area before getting to work, to ensure the most appropriate cleaning solutions and techniques are used to not only this time, but also to prevent further damage, and to preserve our heritage for generations to come.
Why choose Supreme Exterior Clean
The Supreme Exterior Clean team is experienced in dealing with all exterior cleaning requirements and we are well aware of how much of a challenge the unwelcome problem of bird damage to historic buildings can cause.
We keep up to date with the most effective and environmentally friendly products and techniques.
By avoiding the use of pressure-washing and harsh chemicals, we can also protect the area surrounding the surfaces we are working on from unnecessary and accidental damage. Our DOFF steam cleaning equipment is the best in the business, allowing us to take great pride in every job we complete.
As the Stonehealth approved experts in the North East and West Midlands, we not only protect and preserve your stonework, but we also know how to bring out the best in any of your exterior surfaces.
If you are in the North East or West Midlands areas and would like to know more about how we manage such problems as bird damage to historic buildings, more modern structures, commercial sites, or residential properties, please do not hesitate to contact us for a free no-obligation quotation.