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Inspecting Cracks in a Plaster Ceiling: Structural assessment of historic plaster ceilings

Delamination and cracks in plaster ceilings is not something to be ignored, especially in historic buildings where the plaster could be as old as the walls and framework. It is especially important in listed buildings where there are extra controls over what can be done to a building’s interior, which can make repairs more complex.

Regular inspections are good practice for particularly important heritage assets, and ceilings are no exception. If you identify cracks or changes in the appearance of a historic plaster ceiling, you should seek expert guidance.

Lime and fibrous plaster ceiling surveys

There are two types of heritage plaster ceilings that require specialist expertise for structural assessment, lath and plaster, and suspended fibrous plaster decorative ceilings. Below we explain each type and why it is important to have periodic structural inspections to monitor their integrity.

Both types of plaster are not immune to degradation and damage caused by exposure to moisture, heat or vibration. These factors can cause the fixings of the plaster to become compromised leading to cracks in the ceiling, partial failure or a full ceiling collapse.

Plasterite carry out professional ceiling survey inspections to assess the condition and deterioration of plasterwork, either as a one-off activity or as part of an ongoing monitoring and maintenance programme.

image of a fibrous plaster ceiling in a public venue

The issues for owners and operators of buildings open to the public

If you are responsible for a building that is open to the public, such as a performing arts theatre, hotel, place of worship or civic centre, you have a responsibility for people’s safety. The Health and Safety at Work etc. Act 1974 places duties on employers and the self-employed to ensure, so far as is reasonably practicable, that people are not exposed to risks to their health and safety while on the premises. This duty covers employees, contractors and the public using a venue.

Lath and plaster ceilings

Lath and plaster ceilings are created by the method of forcing lime plaster mixed with a binder, such as horsehair, over and through gaps in timber laths that are the framework of the ceiling. The ceiling relies on the plaster forming nibs behind the laths to hold it in place against gravity. The technique derives from a more basic historical building method called wattle and daub that’s been used for at least 6000 years.

Over time, heat, vibration or moisture can cause the integrity of the nibs to fail which causes the lath and plaster ceiling collapse this traditional technique is known for. However, there are some tell-tale signs of a failing lath and plaster ceiling, and if correctly identified, repairs and preventative maintenance can be undertaken to secure and safeguard it. Only a professional ceiling survey will identify the extent of any failing and provide the correct advice to address it.

Fibrous plaster ceilings

Fibrous plaster was an invention of the Victorian area and dates from the mid-19th century. An appealing feature was the decorative possibilities this material provided to architects and builders of the period, allowing intricate shapes and patterns to be moulded to the visible surface. Fibrous plaster is often associated with Victorian and Edwardian theatres and music halls, but it was fitted in a wide range of buildings in the UK through the years.

Fibrous plaster ceilings are created from cast sections fixed to ceiling joists using nails or screws. However, where installed below roofs (within the area called the ‘ceiling void’), they are usually suspended on a framework of timber battens and metal rods. The binding mechanism between the ceiling and its supporting framework is wads of hessian fibres soaked in plaster. Sometimes mechanical fixings (galvanised wire) were also incorporated for additional security – but not always.

In cases where suspended fibrous plaster ceilings have failed, it is usually because no wire was included in the fixing wads. Fibrous plaster is vulnerable to the same issues as lath and plaster ceilings, moisture, extreme heat or continued vibration. The only way to be certain of the status of a suspended fibrous plaster ceiling is to survey it regularly. Firstly, to identify its makeup and structure, and then to monitor its condition and any external factors that could cause damage to it.

Further guidance regarding the inspection and maintenance of fibrous plaster can be found in the document titled Historic Fibrous Plaster in the UK produced by Historic England.

More information on the requirements of Suspended Fibrous Plaster Ceilings; Survey, Certification, Record Keeping etc. can be found in ABTT Guidance Note 20 produced by the Association of British Theatre Technicians, with relevance beyond just performing arts venues.

How ceiling inspections work

Firstly, contact us to establish your enquiry and discuss the parameters of a ceiling survey. Once a date has been established for a ceiling assessment to take place, our expert will attend the property and begin by gaining an understanding of the layout of the building, it’s history and fabric, before inspecting the nominated areas. Where possible, access behind the ceiling is required to achieve the most thorough survey. Should this not be possible then certain techniques can be employed from the visible side to better understand the ceiling’s condition. Once the inspection has been completed, including any photographs and measurements, a report will be produced summarising the activity and offering any advice.

Survey cost

Plasterite has access to experienced surveyors that undertake professional plaster ceiling inspections, producing a detailed report with recommendations and an itemised schedule if remedial work is required. Plasterite has been a plaster manufacturer and installer since 1976.

The cost of a plaster condition survey, inspection and assessment starts at £500.00 per day.

Costs can vary depending on access, height and location requirements. Please contact us for more information and to book an appointment.

Why us?

Plasterite is a fibrous plaster and traditional lime plaster specialist. Our staff have decades of experience working in old buildings, inspecting and repairing ceilings in particular. Using a combination of our extensive knowledge and industry best practice we will confirm the integrity of your ceilings and provide a report giving you both peace of mind and a plan for the future.