Spotting cracks in ceilings can leave you worrying about what the problem might be. In some cases, cracks can signal serious structural issues. But don’t panic straight away, they are usually a natural sign of a building ageing rather than an indication of imminent ceiling collapse.
How you repair old ceilings depends on whether the problem is superficial or structural. How can you tell if your ceiling is simply showing its age or hinting at something more concerning? Here, we explore when to relax and when it’s wise to call in professionals.
An expert in building surveying, Andrew has over 25 years of experience in the residential property sector and a wealth of knowledge on the subject.
Causes of cracks in ceilings
Andrew Pemberton, senior manager of the Professional Snagging Company, says, “Minor hairline cracks are the most common in new-builds.” He adds, “We rarely see large cracks over 3mm wide."
The reasons behind cracks can differ. Pemberton shares some of the reasons why they happen: "From our experience, ceiling cracks can appear in new builds during frequent temperature changes, which causes the timber beams to expand and then shrink. This causes hairline cracks to appear on ceilings.” He adds, “When there are temperature changes due to seasonality, this is more common.”
Another reason can be poor construction work, explains Pemberton, “We have also seen tape-related cracks appear in ceilings. The most common cause, from our experience, is sanding the joints before the joint compound is completely dry. ”It's worth noting that all buildings move, and because joints between materials are a potential weak point, any related stresses tend to show up unless disguised by tapes or coving, etc.
Traditional lath-and-plaster ceilings (mostly pre-1930s) are less robust than modern plasterboard and less able to accommodate movement or water leakage, potentially allowing thick sections of plaster to loosen and ultimately drop off. Older properties are also more susceptible to seasonal changes in ground conditions and temperatures.
So, where rigid modern gypsum plasters have been applied to aged ceilings, the resulting tensions between timbers and plasterwork can cause localised cracking. Thin horizontal cracks appearing at ceiling edges may similarly be due to different rates of expansion and contraction between masonry walls and timber ceiling joists.
Water leakage from overflowing showers, baths and leaky pipes is a common cause. Water usually finds its way through any lighting points and along joints, leaving a distinctive light-brown stain, often exposing the strips of tape between sheets of plasterboard.
Shop these tools and products to help repair cracks in ceilings
A basic square edge plasterboard available in 12.5mm and 9.5mm thickness.
All you need to start filling hairline and small cracks in ceiling and walls. The set includes ready-mixed filler, scraper and multi-grit sandpaper for a smooth finish.
A corded handheld orbital sander that boasts a powerful 3.0 amp motor, a hook and loop system for attaching sanding pads, improved dust collection and a one-handed locking dust bag.
Are the cracks in your ceiling a serious problem?
One of the most worrying scenarios is where cracking is caused by dangerous, unsupported loadings balanced precariously above ceilings. This typically occurs where botched structural alterations have been carried out, such as DIY removals of chimney breasts or load-bearing walls.
Cracking here will normally be fairly localised with associated unevenness and bulging. If this is suspected, you need to urgently check whether anything suspicious is located directly above the ceiling and seek professional advice, which in most cases would be a structural engineer.
Broader ‘structural’ causes, such as settlement at the foundation level, will likely result in pathways of associated cracking appearing in nearby walls, typically with significantly wider cracks forming around the edges of ceilings (unless obscured by coving). Horizontal cracking along the tops of bedroom walls where they meet the ceilings could also be a symptom of movement in the roof structure.
When it comes to historic lath and plaster ceilings, surveyors and builders are sometimes accused of being unduly alarmist. This is because the fine strips of wooden ‘laths’ that make up the structure of these ceilings can sometimes come loose from the joists they’re nailed to, as a result of movement or vibration in the floors above or because of water leakage. This can cause the plasterwork to lose its ‘key’ and drop away in chunks.
But condemning all older ceilings on the basis of such potential risks can be misleading. When sections of old plasterwork are suspected of having broken away, a simple way to assess their firmness is to tap them and listen for a hollow sound. Any loose laths should be checked for timber decay, and any defective areas isolated before carrying out localised repair or replacement work.
Diagnosing structural cracks
If you have persistent ceiling cracks, they should be inspected by a professional. Pemberton says, “Only the professionals can properly diagnose these cracks, but this can be chartered surveyors or structural engineers. Snagging inspectors can also diagnose a ceiling crack by finding the cause and severity."
Pemberton explains the difference between the two, “Chartered surveyors are building surveyors who can complete a house survey for you, whereas a structural engineer specialises in the building’s structure.”
He continues, “They can come into play both during a building’s construction and a renovation.” He adds, “Surveyors are needed during the purchasing process. Snagging inspectors are independent building inspectors who can complete this both before and after building completion. They specialise in inspecting new build properties."
If you notice fresh cracks appearing, it’s probably worth instructing a structural engineer to focus on the specific issue rather than paying for house surveys such as a ‘whole house survey’. Any movement elsewhere in the building needs to be investigated and appropriate solutions devised.
Pemberton points out the cost for a survey, “Home surveys can range between a couple of hundred and £1.5k, depending on the size of the property and the survey level. For homebuyers (level 2), prices typically cap out at £1k.” He adds, “A snagging survey can cost between £300 and £400."
Fixing cracked ceilings
This largely depends on the type of ceiling you are dealing with. Modern plasterboard ceilings are surprisingly durable and, in most cases, can accommodate water leakage or localised movement without major trauma.
However, if there are problems, they can be repaired. Pemberton shares how to deal with minor cracks, “The task of repairing a slightly cracked plasterboard ceiling would involve opening the crack up, removing any loose material, and applying fibreglass tape to seal the crack. Then plastering this over with joint compound and leaving this to dry before sanding and painting.”
For minor cracks, you can use a suitable filler (like this Ronseal Smooth Finish Filler from Amazon). When dry, sand down and paint. Bowed or damaged areas can simply be cut out and patched with new sheets of plasterboard, then filled and taped the joints, and finally plastered to match the surrounding surfaces.
Cracking linked to different rates of thermal expansion between adjacent materials at ceiling edges, which is not structurally significant, can often simply be concealed with coving fitted between the walls and ceilings.
More serious repair work is likely to be required for historic lath-and-plaster ceilings. Once any loose or damaged areas have been isolated, they can be cut out and either infilled with plasterboard or reconstructed by securing or replacing loose laths before replastering.
For added strength, lining paper can be applied over the surface to match the surrounding original ceilings. If extensive areas of old plasterwork have come loose, you may need to replace the whole ceiling with new plasterboard, unless the building is listed or of special historic value, in which case a like-for-like replacement will be needed.
Repairs to cracking caused by structural issues elsewhere in the house will obviously have to wait until the root causes have been addressed. For example, where the rafters have pushed the roof slopes outward, remedial repairs will first be needed to restrain the rafters before replastering.
Nathan Blackler is a home insurance expert at Go.Compare and has over 15 years of experience in the insurance industry. He joined Go.Compare in 2023, having previously worked for Admiral and Confused.com.
Does home insurance cover ceiling cracks?
Whether your home insurance will cover cracks in the ceiling will depend on the type of crack, explains Nathan Blackler, home insurance expert at Go.Compare, “Understanding the type, width, and direction of a crack can help you determine whether it’s cosmetic or a sign of structural concern, and therefore whether it would be covered by a home insurance policy.”
He continues with an example, “Cracks in walls or ceilings that are wider than 2mm, are wider at the top than the bottom and run diagonally could indicate subsidence and should be inspected by a professional.”
If you do have cracks that are caused by subsidence, these are typically covered. Blackler says, “Any cracks that have formed from subsidence are usually covered by home insurance under your buildings policy, but only if your property has not suffered subsidence previously.”
However, he says it is worth noting the excess on the policy, “According to Defaqto, around 93% of all buildings insurance policies have a standard subsidence excess of between £1,000 and £1,499."
For smaller hairline cracks, home insurance is unlikely to cover the issue, shares Blackler, “Home insurance often won’t cover repairs of small, hairline cracks that naturally appear, especially where a new property or extension settles. These types of cracks are considered cosmetic and will be your responsibility to fill and repair.”
If your home has hairline or small cracks between the ceiling and the top of a wall, you can learn how to install coving to hide them. If the cracks are more serious, they will need to be repaired. Check out our cosy living room ideas and loft bedroom decorating ideas to bring a room back to life.
