Lime plastering using traditional lime putty plaster offers advantages over cement based materials and gypsum plasters for the internal plastering of traditional properties, especially when decorated with a natural, breathable paint:
- Their porosity allows the structure to “breathe”.
- They can accommodate general movement better.
- Their self-healing nature reduces cracking problems.
- They can reduce condensation problems
As with all lime plastering, the best outcome requires patience and careful control of drying and suction – the reward being a good looking and long lasting finish.
We also supply a range of clay plasters for use in traditional properties and new build.
Before starting any work, always check if the building is listed. You may need to contact the local authority Conservation Officer to discuss the project before proceeding.
Remove any existing failed plaster and paint. Check the structure for damage. Look out for very thick patches of plaster because these could be load bearing. It may be necessary to plaster on top rather than risk rebuilding an area.
Dampen the substrate with clean water to control when lime plastering before applying each coat. Allow water to soak into the lath before the plaster is applied – control of suction is important but so is surface tension.
Example Lime Plaster Specification on to Solid Walls
- Dub out any deep holes in the wall with a Haired Lime Mortar, rebuilding defects using like for like materials such as cob blocks, cob bricks or stone.
- Treat and counter batten wooden lintels before lime plastering.
- Apply one hand harled coat of Secil Consolidation Mortar to provide a key to the masonry.
- Apply sufficient coats of Haired Lime Mortar to smooth the contours of the wall. The last float coat generally benefits from being unhaired because there is no chance of hair showing through the skim.
- Apply a top coat of our Heritage Lime Plaster based on a very fine sand and lime putty in two passes totalling 3 mm. For the very smoothest of textures, substitute the second pass for a 1 mm skim of our Regency Lime Plaster.
If the wall has a high residual level of moisture that cannot be eradicated (e.g. a high external ground level) it may be necessary to apply a waterproof barrier before lime plastering. We supply a waterproofing slurry for this purpose. Gauge backing coats of lime mortar with Argical M1000 to bring about a hydraulic set.
Lime Plaster Skim
Our Regency or Heritage lime plaster is ideal for a thin skim over a wide variety of backgrounds such as plasterboard, blocks and mixtures of old and new plaster, old paint etc.
Apply a special bonding coat of DG27 for lime plastering on to plasterboard. For bare plasterboard, you must scrim the joints as is usual practice. Apply Heritage Lime Plaster in two passes or an alternative Regency Plaster second pass for the finest of finishes.
Limes are caustic. Always wear eye protection and protective gloves and clothing and follow the safety instructions on the labels.