Yes, hairline or thin, straight cracks in older plaster ceilings are normal. They are usually caused by natural house settling, temperature shifts, or humidity changes. However, wide cracks, "spiderweb" patterns, or sagging could indicate structural damage or failing plaster.
If you have wide, deep, worsening, or multiple cracks on your walls and ceilings, you should be concerned. These types of cracks can be a sign of foundation problems or structural damage, and it's important to have them checked out by a professional.
Common Causes of Ceiling Cracks
They result from poor taping and jointing, or slight movement in the building's structure. Building Settlement: All homes settle over time. Movement causes stress along weak points, especially where different materials meet. This leads to fine, linear cracks.
Fine hairline cracks in plaster are very common and are usually caused by the plaster drying or minor seasonal expansion and contraction of the building. As long as they are not growing or accompanied by the other warning signs, they are typically just a cosmetic issue.
Whether a crack in your ceiling is a cause for concern depends on its size, shape, and accompanying signs. Small, thin hairline cracks are usually normal in older homes as they settle. However, wide, jagged cracks, or those accompanied by sagging, water damage, or door-sticking, require professional inspection.
Hairline cracks of less than one millimetre in width or slight cracks of between one and five millimetres are generally not a cause for concern. If you begin to notice these, they can generally be filled and painted over as they're a crack in the plaster but not in the wall itself.
Warning signs of structural drywall cracks:
Cracks wider than 1/8 inch – A large or expanding crack suggests structural instability. Cracks accompanied by bulging drywall or sagging ceilings – Indicates potential framing or foundation repair.
Yes, plaster cracks much more easily than drywall. Because it is a rigid, dense material with very little flex, it is highly susceptible to cracking over time due to natural house settling, temperature changes, and vibrations. Drywall, by contrast, is more flexible and generally only cracks at the joint seams.
Common Visual Clues to Bad Plastering
Wide, uneven or randomly placed cracks are a clear indicator. Cracks at the edges or corners may mean the plaster did not bond to the wall properly. Another clue is uneven surfaces. Walls might look wavy, bumpy or have noticeable dips.
Scrape off anything loose thencut a "V" along the length of the crack. Fill the groove with easifil jointing compound, cover with paper joint tape and another thin layer of compound. Once it's dry, lightly sand to blend the joint into the surrounding plaster and paint.
Cracked or sagging plaster ceilings are common in older homes, but they don't have to stay that way. With the right tools and techniques, repairing your plaster ceiling is actually a manageable do-it-yourself (DIY) project for most homeowners.
Before collapsing, ceilings typically exhibit clear physical distress. Look for noticeable sagging or bowing, large cracks (wider than 18one-eighth18 inch), and yellow or brown water stains. Additionally, peeling paint, popping screw heads, or hearing cracking sounds from above are urgent warning signs.
Home insurance covers ceiling cracks only if they are caused by sudden, accidental events (like a burst pipe or severe storm). If the cracks result from general wear-and-tear, lack of maintenance, or the house naturally settling, they are considered routine upkeep and are not covered.
You generally don't need to worry about thin, hairline cracks (under 1/16 of an inch) or straight cracks running perfectly along drywall seams, as these are usually just cosmetic or due to natural settling. However, you should call a structural professional immediately if the crack is deep, widening over time, paired with ceiling sagging, or accompanied by water damage.
Key signs that a crack may be structural
Width: cracks wider than 3mm should be monitored; those over 5mm need urgent inspection. The NHBC uses 2mm as a common threshold for cosmetic vs notable cracking. NHBC cracking guidance (PDF). Pattern: diagonal, stepped or horizontal cracks often indicate structural movement.
You can put thin drywall over it, but if it's starting to show cracks and unevenness you will have to rip it all out at some point. I'd recommend doing it right and ripping out the lath and plaster and replacing it with sheetrock. The hardest part is the demo, sheetrocking is pretty easy.
What are the common defects of plastering?
The best condition for allowing your newly plastered walls/ceiling to dry is to provide some ventilation by opening a couple of windows slightly. You can put the heating on, however, we recommend you keep this at a low temperature for a number of days after the plastering is completed.
Plasterer cost per hour
The average hourly rate for a plasterer in the UK is £25 per hour, but varies from £15 to £50 depending on where you live. A plasterer will usually give a price based on the size of the rooms and ease of access rather than how long it will take.
Cracks in the ceiling are a normal occurrence and are often more of a cosmetic issue than a structural issue. However, some cracks in the ceiling might need immediate professional attention.
A sagging or bulging ceiling is a more serious sign of water in the house and possible structural damage — this usually needs immediate attention.
Thin, spiderweb-like cracks: Usually cosmetic and caused by paint or plaster aging. Long, continuous cracks across the ceiling and down walls: May indicate structural movement. Drywall cracks with drywall nail pops: Could signal foundation movement or settling.
When should I call a professional to inspect ceiling cracks? You should contact a professional if cracks are large, extend down walls, are paired with sagging, or show signs of water damage. These can indicate structural issues or ongoing leaks that require expert assessment.
Warning signs of a ceiling collapse include visible sagging or bowing, rapidly expanding cracks, heavy water stains, and structural sounds like creaking or popping. If you notice a drooping ceiling or soft drywall, leave the room immediately and contact a professional contractor or emergency services.