Why can't I use gypsum plaster on my old house?
Traditional solid-wall buildings manage moisture by allowing it to move through the fabric of the wall and evaporate. Gypsum plaster is relatively impermeable and reduces this movement, trapping moisture inside the wall. Over time this causes persistent damp, salt damage, and deterioration of the masonry. Lime plaster is vapour-permeable, flexible, and compatible with the original materials. For any building with solid walls, stone, cob, brick, or rubble, lime is the correct internal plaster.
Can lime plaster be repaired without re-doing the whole wall?
Yes, but the repair must be done in lime, matched to the existing specification. A gypsum patch on a lime wall will behave differently under moisture and temperature change, eventually delaminating or cracking at the junction. Riley's assesses the existing plaster before any repair to match the mix and coat structure. Well-executed lime patch repairs are virtually invisible.
How long does internal lime plaster take to cure?
Each coat of lime plaster requires a minimum of 3 to 7 days before the next coat is applied, depending on conditions. Full cure of the finish coat before decoration is typically 4 to 8 weeks for hydraulic lime plasters, and longer for lime putty-based finishes which cure through carbonation. Decoration must wait until the plaster is fully cured. Painting over green lime plaster prevents carbonation and causes failure.
Is lime plaster suitable for listed buildings?
Lime plaster is not just suitable for listed buildings, it is often required. Listed building consent conditions and conservation officer guidance frequently specify lime-based materials for internal work. Applying gypsum plaster to a listed building without consent could constitute an unauthorised alteration. Riley's is familiar with listed building requirements and works within them as standard.
Can you replicate lath and plaster on a traditional property?
Yes. Lath and plaster reinstatement is part of Riley's scope. New riven or sawn timber laths are fixed to the substrate and three-coat lime plaster is applied in the traditional manner. On listed buildings and in conservation areas, this is often the required approach rather than dry lining or plasterboard. The result is a breathable, authentic internal finish consistent with the original construction.
How do you decorate over lime plaster?
Lime plaster must be fully cured before decoration. The correct paint for new lime plaster is a breathable mineral paint or limewash, which allows moisture vapour to continue moving through the surface. Standard vinyl emulsion significantly reduces permeability and is not recommended on fresh lime. On older, fully carbonated lime plaster, breathable emulsions can be used. Riley's advises on decoration specification as part of every plastering project.