Heritage properties carry more than just aesthetic value; they hold history, craftsmanship, and the character of their era. Preserving these homes isn’t just about restoring their appearance; it’s about using the right materials and techniques so that the structure can keep breathing, moving, and standing for decades to come.
Unfortunately, many well-meaning renovations fail because modern, incompatible materials are used in place of traditional ones. Here we’ll focus on three common culprits: cement, acrylic paint on exterior brickwork, and finger jointed pine in exterior applications; and why each can cause lasting damage.
Cement Mortar – A Hard Problem for Soft Brick
The problem:
Heritage brickwork (pre–20th century) was generally laid with lime based mortar, which is softer and more flexible than modern Portland cement. Bricks from this era were often hand pressed, more porous, and designed to work in harmony with lime mortar.
Why cement is incompatible:
Rigidity and brittleness: Cement mortar doesn’t flex with temperature and moisture changes the way lime mortar does. This leads to stress being transferred to the brick rather than the joint.
Moisture trapping: Lime mortar is breathable; it allows moisture to evaporate through the joints. Cement mortar is dense and impermeable, forcing moisture into the bricks where it can freeze, expand, and cause spalling (surface flaking).
Irreversible damage: Over time, cement mortar can cause surrounding bricks to deteriorate faster than the joints themselves; meaning repairs become more expensive and invasive.
Better alternative:
For heritage brickwork, always use a lime based mortar mix tailored to the brick’s hardness. It will protect the bricks, allow the wall to breathe, and make future repairs easier.
Acrylic Paint on Exterior Brickwork – Trapping Trouble Beneath the Surface
The problem:
It’s tempting to give old brickwork a “fresh coat” of modern paint for a uniform, clean appearance. Many homeowners even ask “can you paint exterior brick” or wonder “should I paint my brick house” to improve its look. Acrylic paints—while durable on many modern surfaces—are the wrong choice for historic masonry.
Why acrylic paint is harmful:
Seals in moisture: Acrylic forms a plastic-like film over the surface, stopping bricks from releasing internal moisture. This can lead to blistering, peeling, and salt efflorescence.
Encourages hidden decay: While the painted surface may look fine for a while, trapped moisture behind it can rot timber lintels, rust embedded metal, and accelerate brick deterioration.
Difficult to remove: Stripping acrylic paint from heritage brick without causing damage is expensive and often imperfect, leaving permanent scars in the brick face.
Better alternative:
If painting is absolutely necessary, a mineral based silicate paint or limewash is a breathable option. In most cases, the best approach is to gently clean and maintain the original brick surface, allowing its natural patina to remain. If you’re asking yourself “can I paint the brick on my house”, the safest advice for heritage homes is usually: don’t paint—preserve.
Finger Jointed Pine Outdoors – Built In Weakness
The problem:
Finger jointed pine is made by gluing short lengths of timber together in a zig-zag “finger” pattern, often marketed as a cost effective and straight option for joinery. While it can perform adequately indoors, it’s ill suited for exterior use; especially on heritage properties.
Why finger jointed pine fails outdoors:
Glue line vulnerability: The adhesive joints break down quickly under UV exposure and moisture cycling, leading to separation and warping.
Inconsistent durability: The timber pieces joined together often vary in density and grain, leading to uneven weathering.
Short lifespan: Even when painted, outdoor finger jointed pine can begin to fail within just a few years, meaning frequent repairs or replacements.
Better alternative:
For heritage joinery exposed to the elements such as fascia boards, window sashes, and verandah posts; use naturally durable, solid timber species suited to your climate. Australian hardwoods like spotted gum, blackbutt, or cedar are proven performers, and when maintained, can last for decades.
Final Thoughts – Respect the Building, Respect the Materials
Restoring a heritage property is about working with the building, not against it. Materials like cement mortar, acrylic paint, and finger jointed pine may seem like quick or modern solutions, but they often shorten the life of original fabric and add to long term repair costs.
By choosing breathable, flexible, and durable materials that match the home’s original construction, you protect both its structural integrity and its heritage value. This isn’t just good conservation practice; it’s an investment in the home’s future.
