Ines CallowayArchitecture & Interiors

Notes on specifying lime plaster

Four things we now write into every specification for lime plaster on old masonry.

Lime plaster on old masonry fails for boring reasons. After two projects we now write these into every specification:

  1. Name the lime. “Lime plaster” is not a specification. State natural hydraulic or non-hydraulic, and the class.
  2. Programme the drying. Coats need days, not hours, between them. Put the days in the programme so nobody is tempted to hurry.
  3. Ban the heaters. Space heaters dry the surface before the body has carbonated. Write it down.
  4. Keep a sample panel. A square metre, left in place until handover, settles every argument about texture.