Excerpt: Do you have damp patches on your walls or crumbling brickwork? The culprit might be modern cement. Learn why traditional lime plaster is essential for the health of your historic property.

Owning a historic property is a privilege, but it comes with a unique set of responsibilities. One of the most common mistakes we see in period home renovations is the use of modern materials—specifically, standard cement render and gypsum plaster—on older walls.

While these materials work perfectly for modern cavity-wall houses, they can be disastrous for timber-framed or solid-stone buildings.

The “Raincoat” Effect Modern buildings are designed to be sealed units. They keep moisture out using damp-proof courses and cavities. Think of them as wearing a plastic raincoat.

Historic buildings, however, were built to work like an “overcoat.” They are constructed with solid walls that absorb moisture from the rain and the ground, but then release it back into the air through evaporation. This process is often called “breathability.”

The Danger of Cement When you cover a solid stone or brick wall with impermeable cement, you trap that moisture inside the wall. It can’t escape outwards, so it travels inwards, blowing your internal plaster or rotting the structural timber frame hidden within the wall.

Why Lime is the Answer Lime plaster and render are traditional, breathable materials used for centuries. Unlike cement, lime is porous. It acts like a wick, drawing moisture out of the wall structure and allowing it to evaporate naturally.

The Benefits of Switching to Lime:

• Drier Walls: Prevents damp buildup and mould growth.
• Warmer Home: Dry walls provide better insulation than wet ones.
• Flexible: Lime is less brittle than cement, meaning it moves with your building and is less likely to crack.

If you are noticing damp issues in your period home, the solution isn’t more waterproofing—it’s often removing the modern cement and returning to traditional methods.

Do you have concerns about the render on your property? Contact Morris & Hughes today for a consultation.