Why Lime Plaster Outperforms Gypsum
An Unearthed Project - East Sussex
Building for Health and Longevity
At Unearthed Build, we often get asked why we choose lime plaster over gypsum. The answer is simple: lime not only protects buildings but also supports human wellbeing. It’s an ancient material with modern relevance — sustainable, breathable, and beautifully versatile. Here’s why we believe lime is the healthier, longer-lasting choice for both people and buildings.
1. Breathability and Moisture Control
Lime plaster allows walls to breathe. Unlike gypsum, which creates a dense, sealed surface, lime is vapour-permeable. This means moisture can move naturally through the walls, reducing condensation and preventing trapped damp.
Health impact: Fewer damp issues mean fewer mould spores, which are known to aggravate asthma, allergies, and respiratory conditions.
Building impact: Breathable walls regulate humidity, protecting the structure and preventing costly repairs.
2. Natural Antibacterial and Antifungal Properties
Lime is naturally alkaline, creating an environment that resists bacteria, mould, and fungi. Gypsum, on the other hand, can absorb moisture and harbour microbes.
Health impact: Lime’s antimicrobial qualities help create a cleaner, healthier indoor environment.
Building impact: Surfaces stay fresher for longer, reducing maintenance needs.
3. Thermal Comfort and Energy Efficiency
Lime plaster contributes to thermal mass, helping buildings regulate temperature. Its natural porosity buffers heat and humidity, keeping interiors cooler in summer and warmer in winter.
Health impact: A more stable indoor climate supports wellbeing, especially for those sensitive to temperature fluctuations.
Building impact: Better energy performance reduces heating and cooling costs.
4. Durability and Flexibility
Lime is more flexible than gypsum. It can accommodate small movements in a building without cracking, making it especially valuable for older properties.
Health impact: A healthy building is a stress-free building — no recurring cracks or damp repairs to deal with.
Building impact: Lime plaster can last for centuries if cared for, whereas gypsum often needs patching or replacement.
5. Sustainability and Ecology
Lime is one of the most sustainable building materials available:
It reabsorbs CO₂ during curing, offsetting much of the carbon released in its production.
It is non-toxic and free from synthetic additives found in many gypsum plasters.
Health impact: No hidden chemicals, low VOCs, and a natural finish mean better indoor air quality.
Building impact: A truly circular, low-impact material that honours both heritage and modern eco-standards.
A Return to Human-Centred Buildings
Choosing lime plaster is more than a technical decision — it’s a commitment to healthier living and sustainable building. At Unearthed Build, we see it as part of a bigger shift: creating spaces that are kinder to our bodies, our minds, and the planet.
