One of the most common mistakes on an old home is treating it like a new one. Modern materials are often designed to seal moisture out. Older homes were built to let moisture move through and escape. When you mix the two up, you cause problems that can take years to show.
How old walls handle moisture
Solid masonry walls, the kind you find on many older Sydney homes, take in a little moisture and then let it dry back out. Lime renders and mortars were made to work with this. They are soft and open, and they let the wall breathe.
What goes wrong with modern materials
Hard cement renders and plastic-based paints do the opposite. They seal the surface. On a modern cavity wall that is fine. On a solid old wall, the moisture that used to escape gets trapped. It moves along until it finds a way out, often taking salts with it, and that is when you see damp patches, blown render and peeling paint.
The role of breathable paint
Paint matters here too. A breathable, mineral or heritage-grade paint lets the wall keep moving moisture. A sealing paint holds it in. This is why the right paint system on an old home is about more than colour.
What this means for your home
- Use lime-based renders and mortars on solid masonry
- Choose breathable paint systems rather than sealing ones
- Treat the cause of damp, not just the surface
- Match materials to the age of the home
None of this is about doing things the hard way for its own sake. It is about working with how the home was built, so repairs last and the walls stay healthy.
We choose materials to suit the age of the home on every job. Read more about our remedial repairs and heritage painting, or get in touch for a free on-site quote.