Lime mortar and plaster for fireplaces

As part of our stove installation service and where we are “knocking out”, enlarging or building a fireplace, we can offer the option of having the fire opening rendered in Lime (to be precise that’s a base coat of a lime and hemp mix with a lime plaster finish coat).

Lime is a traditional building material with a number of advantages over modern materials:

– it breathes and lets moisture out so is particularly suitable for Victorian brick buildings and older Cotswold stone buildings which don’t have cavity walls or damp courses.
– any small cracks that appear as a building settles, typically get sealed up naturally as the lime mortar/plaster re-carbonates (Lime does not “dry out” in the way we’re used to with modern materials. It sets through a process of carbonisation as it is exposed to Carbon Dioxide CO2 in the air)
– lime is a softer material than modern cement and plaster which means it will give rather than cracking Cotswold stone
– it is a traditional material free of any chemicals, particularly suitable for older buildings and new environmentally friendly buildings. It is usually required for any Listed building.
– using Lime to render a fireplace takes no longer than using sand and cement

There’s one thing to watch out for when choosing to have a fireplace rendered in Lime. Lime takes longer to set through the process of carbonisation than the time sand and cement takes to dry out. So, to minimise the risk of plaster cracking, instead of recommending the stove in a newly rendered fireplace isn’t used for 1 week, we recommend the stove isn’t used for 4 weeks.