Black bitumen paint: A warning for heritage homes
At Heritage Lane, we believe in preserving the integrity of period and listed buildings. This page addresses the common misconception surrounding black bitumen paint and its detrimental effects on traditional structures. Learn why this product should be avoided for historic property maintenance.
Why black bitumen paint is unsuitable for period properties
A disturbing trend emerged years ago: applying a black painted line around the base perimeter of houses. This practice, often seen as a quick fix, especially where there is a footpath alongside thevexternal walling, should never be undertaken on period or listed buildings.
Unlike traditional breathable materials, black bitumen paint is another material that creates an impermeable barrier, trapping moisture within the walls, leading to significant and often costly damp issues, remember that the Damp Proof Course should be 6 inches (150mm) at the minimum above ground, so think about how that 15omm of brickwork can dry again after it has rained?
Again, it fundamentally misunderstands the importance of moisture movement in traditional construction.
Who should avoid black bitumen paint?
Simply put, this product is best suited for paranoid, unknowledgeable people, including the damp 'special needs' people who just want another holiday in the gulf of Mexico!
Knowledgeable conservationists will know better.
It is certainly not suitable for homeowners, builders, or anyone involved professionally in the conservation or restoration of period and listed buildings.
While some marketing claims might suggest its utility, these are often misleading and designed to sell an unnecessary product that ultimately harms the building's fabric.
Common issues and why bitumen paint exacerbates them
Black bitumen paint is an old trick, that paranoid homeowners used to stop the invented term of "rising damp" because they did not understand the importance of moisture movement in traditional builds, and of course the marketing (lying) started back in the early 1960's.
Marketing has since misrepresented this product, and still does, leading people to believe it's a solution for damp.
When in reality, it actively creates and worsens damp issues by preventing the natural evaporation of moisture from the wall's surface, leading to structural problems with ground floor joists, attracting beetle infestations, and increased humidity internally.
Our unequivocal advice
If there is one thing Heritage Lane wants to convey about black bitumen paint, it is this: used on the insides of traditional metal guttering is fine as a waterproofing coating to help prevent rust is OK. However, It will trap moisture in your walls and create damp issues, compromising the health and longevity of your period or listed building. Always opt for "breathable", traditional materials and methods when dealing with historic properties.