Stucco Classico: One-Coat Lime Stucco

Interior Lime Stucco

This is a repair done in the cellar of an early 19th century home in one-coat lime stucco or lime plaster.  This is a particular type of one-coat work called "dinging."  This type of work is a cost effective way of obtaining the benefits of lime plaster or lime stucco.  It is suitable for cellars or exteriors as a covering over rough stone or masonry.  In this instance, the homeowner had hired a worker to do a basement waterproofing job.  The worker offered to do stucco job on the surrounding area.  The homeowner agreed, but requested lime stucco.  Unfortunately, the worker did little preparation and used incorrect materials.  The job failed, as evidenced by numerous cracks virtually everywhere.  We removed this new material and the unsound material below it.  Structurally-sound material (portions of the cement stucco) was left behind.  This was an interior job in very close quarters (heating equipment made access difficult in certain areas), so demolition was minimized.  The base was hard yellow stone.  This was first covered long ago with clay and sand.  At some point, a hard waterproof synthetic material was added.  This was painted several times over the years.  Some areas were patched with cement.  As much synthetic material as was possible to remove was taken off.  The clay/sand stucco generally came with it.  Were it not for the synthetic coating, the clay and sand would have been still sound.  Clay was commonly used on older homes due to reasons of economy.  It is not very abrasion-resistant and cannot withstand weather, but it is easily repaired and very moisture-permeable.

For the repair, those areas that had sound synthetic material were treated with acrylic modified lime stucco to allow the stucco to adhere.  For covering the rocks, a hard stipple coat was first applied.  Some dubbing of deep recesses was done prior to the application of one coat of coarsely aggregated Saint-Astier NHL 2.  This material was chosen for this application since it has a high free lime content, meaning it can move with the structural changes.  Additionally, it has a high vapor permeability.  Some hydraulic set was needed since certain areas of the cellar remain damp for extended periods.  The work was float finished to leave an open texture to allow acceptance of whitewash.  Windowsills and vulnerable corners were done in eminently hydraulic lime to make them more durable.  Some other somewhat less exposed areas were done in moderately hydraulic lime.  The different types of lime are not visually distinct.

The end result was coarsely-textured float finish topped with whitewash (also called limewash).  The finish chosen was due mainly to economy: In one-coat work, a coarse aggregate is needed to fill large irregularities.  A coarse float finish is necessary so that the limewash will be able to adhere.  If a different texture were requested, an additional coat would have been required.

For work on older structures with load-bearing masonry walls, consider one-coat lime stucco by Stucco Classico.