We pose a few frequently asked questions about plaster ceiling surveys to our resident expert to understand more about when a plaster ceiling should be inspected and the benefits of a professional survey.
Peter, how long have you been a surveyor of plasterwork?
I started working for Artisan Plastercraft as a Surveyor in September 2015, but I have worked in building construction for over 35 years, with and around plastering and associated trades. I now lead the survey team and spend most of my time visiting client sites to carry out surveys or assist in the assessment and pricing of plasterwork.
Who are your typical clients for ceiling surveys?
We carry out annual ceiling inspection surveys at popular public venues such as the Royal Academy of Arts, British Film Institute and EartH Hackney, and have completed one-off surveys at various times for the likes of Battersea Arts Centre, Shakespeare’s Globe Theatre and The Savoy.
What are the different types of plaster ceilings you typically work with?
There are two types of traditional plaster ceiling that can require periodic or regular inspections.
Suspended Decorative Plaster Ceilings – often found in theatres and other large entertainment spaces, these ceilings are made from fibrous plaster mouldings fixed to a framework supported by ‘wads’ of hessian dipped in plaster. In some instances no mechanical fixings were employed, and the plaster wads can be vulnerable to age and moisture. Hence the requirement to monitor their condition, as in some high-profile instances, they have failed.
Lath and Plaster Ceilings – the application of traditional lime plaster over rows of thin strips of wood. Again, no mechanical fixings are employed, the plaster relying on ‘nibs’ formed behind the laths to hold it in place against gravity. Sometimes heat, vibration or moisture can cause the integrity of the nibs to fail, which causes the lath and plaster ceiling to sag or collapse. It is sometimes possible to re-secure affected areas with mechanical fixings but only after a survey has assessed the whole ceiling.
In what circumstances is it important to have a plaster ceiling surveyed?
It very much depends on the building age and construction, but any large-scale suspended fibrous plaster ceiling should be assessed to establish its condition and if mechanical fixings have ever been employed. As these types of ceiling were prominent in theatres and performance venues of the late nineteenth and early twentieth centuries, many of which are still in use today, understanding the ceiling condition is a matter of public safety.
A lath and plaster ceiling will typically show signs of failure before its collapse, so it is important to be aware of any signs of sagging or changes in the ceiling line. A survey will reveal any compromised areas and could allow localised repairs to give the ceiling many more years of life.
How often should these be inspected?
After an initial ‘baseline’ survey has been completed, a recommendation is made as part of the condition report to identify if and when further inspections are required. If a ceiling is deemed to be vulnerable then an annual inspection is good practice, but it depends on many factors.
Can you give one example of a recent ceiling survey you completed?
We complete annual inspections at the Royal Academy of Arts. In the main galleries there are decorative fibrous plaster ceiling sections which are monitored in detail by using a scissor lift.
Where can building owners and managers find out more information?
We have more information about Plaster Ceiling Surveys on our website, however there are two important documents, one titled Historic Fibrous Plaster in the UK produced by Historic England, and another titled ABTT Guidance Note 20 produced by the Association of British Theatre Technicians that give valuable guidance regarding the inspection and maintenance of fibrous plaster ceilings. Well worth a look.