A family run business in Kent : Quality fibrous plaster and external cast stone mouldings since 1976

Lath and Plaster Ceilings

Many historic buildings feature lime plaster coated ‘lath and plaster’ ceilings or walls. There are different methods for applying lime plasters, but one of the most common found in older properties is lath and plaster. Employed from the early 18th century right up until the mid-20th century, lath and plaster references the use of a timber structure that the lime is spread over.

Laths are essentially narrow wooden slats that are evenly spaced apart on a ceiling between the beams and joists. Hydraulic lime plaster is applied over the top of the laths, usually in three separate coats, to form the internal ceiling surface. The process of pressing the first coat of lime onto and through the gaps in the laths to form a key is what holds the ceiling plaster in place. 

image of timber laths for plaster ceiling

Lath and plaster ceiling lifespan

How long will a lath and plaster ceiling last, is a question that is very hard to answer. This is mainly due to so many factors influencing ceiling lifespan. Size, building construction, type of lime plaster and the skill of application will all have an effect. We have worked in buildings with a lath and plaster ceiling lifespan of decades, whereas a poorly applied product may only last a matter of years. Expertise is the key to longevity, and working with a specialist that understands lime plasters and can demonstrate their knowledge and project experience.

Only a full ceiling condition survey will provide an expert summary of the integrity of your lime plaster ceiling.

Why do lath and plaster ceilings collapse?

The most common source of damage to plasterwork is moisture. This can be dampness over a period or a sudden water leak such as a burst pipe or flood. Old plaster can also be compromised by sustained vibrations and/or damage caused by DIY or other building work, so extra care should always be exercised with historic buildings. What often causes a lath plaster ceiling to collapse is when the plaster separates from the laths so that the weight of the plaster cannot support itself.

image of lath and plaster ceiling scratch coat

How to fix lath and plaster cracks

If you identify cracks in a lath and plaster ceiling, there are steps you should take depending on the severity of the damage. Small cracks should be monitored closely over time to see if they worsen. Large cracks or any visible change in the surface of the plaster, i.e. sagging or a bow in the ceiling, should be urgently investigated. Always take digital photographs, as these will help monitor any changes in condition and can be used as supporting information when approaching an expert.

The process for repairing lath and plaster ceiling cracks should first be addressed with a knowledgeable specialist inspecting the affected areas of the ceiling. From this it will be possible to establish if a localised repair can be undertaken. Individual circumstances will dictate what the remedial steps will be. If your property is a listed building then any repair work will need to be run past your local conservation officer for consent.

Should I overboard a lath and plaster ceiling? Find out here.

image of plaster application over timber laths

Lime plaster ceilings

If you are looking for a heritage lime plasterer near you in the Kent, Sussex or London areas then Plasterite can assist you. We operate throughout the southeast of England providing lime plaster ceiling services. Our expert team have decades of experience in conserving and restoring plasterwork in heritage and listed buildings. A company representative can visit your property to give you an estimate for lath and plaster ceiling repair. The first step is for you to contact us with your building age, location, ceiling dimensions, and images of the areas of concern and we will get back to you.