Lath & Plaster
Until about 70 years ago ceilings and internal partition walls were lined with individual strips of timber lath and plastered over with lime mortar. The laths themselves, about an inch or an inch-and-a-half wide, were made from riven or split timber, and were individually nailed to each ceiling joist or wall stud. Lathing a new house would use thousands of small nails, individually hand-made in a smithy and each hammered in by hand. The old laths were slightly tapered and often split as they were nailed.
When repairing a lath wall or ceiling it's best to use matching materials, as the movement characteristics will be the same, lessening the likelihood of cracking. Despite the modern advances in making plasterboard, lath-and-plaster is superior, not only because it doesn't crack, but also for its sound-proofing properties. Traditional lime plaster is much denser than the gypsum which makes up plasterboard and so this helps absorb low-frequency sound. In addition, the way the plaster oozes between the laths leaves an irregular surface which cuts down on vibrations. So despite all our modern advances, good old fashioned lath and plaster has its advantages over new materials!
