Most homes have a few imperfections or quirks that have been there for as long as you can remember: One replacement bathroom tile that doesn't quite match the others, an old doorknob that sticks, or perhaps a gouge in the wainscoting. There are also the minor defects that make you second guess your memory; more specifically, whether they're new, or they've always been there, but you've never noticed them before.
Hairline cracks in walls and ceilings often fall under the second category. It can be difficult to determine whether they're recent—and possibly a sign that something is amiss—have long gone unnoticed, or disappear and reappear seasonally based on temperature fluctuations. That's why it's a good idea to mark or document these cracks when you first see them, instead of relying solely on your memory.
How to mark and monitor cracks in your walls and ceilings
Living in a rented apartment on the top floor of a nearly century-old building, I've seen—and marked—my fair share of wall and ceiling cracks. Like many apartment buildings constructed at this time, mine has lath-and-plaster walls and ceilings. Often highlighted in marketing brochures of the era for their fire- and sound-resistant qualities, plaster walls and ceiling are also more prone to cracking than those made using drywall, which are more common today. Here's how I keep track of mine:
Mark the endpoints with a pencil
First, I put light pencil mark at each of the crack's endpoints, and write the date—including the year—next to one of them. Though I write directly on my walls using a pencil that I know erases well, that may not be an option for everyone.
To avoid marking the wall or ceiling itself, Alexandra Cooper, an architect and interior designer at Planner 5D, suggests placing a piece of transparent tape over the crack first. "This can help prevent the crack from widening further, and also provide a clear surface for marking," she says.
In addition to marking cracks that you've noticed for the first time, you may also want to consider doing the same for those that you've been aware of for a while, in order to determine whether they grow or change over time.
Take photos
Next, I take well-lit photos of the crack standing directly in front of it, as well as from a few other angles and distances. Not only are the images helpful visual references for monitoring the crack, but they also provide another record of the date and time. This is especially handy if you're a short person with tall ceilings that you can only reach using the extra-tall ladder that you have to borrow from your building's maintenance person, for instance.
Check it periodically
If the crack appeared after some extreme weather, for example, you'll probably want to check it on a near daily basis—at least for the first week or so—to see whether there's any active movement or additional shifting resulting from the event. Once you're convinced that it's relatively stable, or if there wasn't a clear cause and you've just noticed what was probably an existing crack, check it every month or two. If you haven't observed any changes, you can probably cut back to every six months or year.
The key, at least for me, is to put reminders to check the crack in my calendar, immediately after marking and photographing it on the day I first notice one. Otherwise, if it's not somewhere directly in my line of vision, I will probably forget.
Document any changes
As soon as I notice that a crack now extends beyond its previous endpoints, I mark and date the new ones and take a few new photos showing the growth. I haven't seen much movement over the years, so this is the extent of what I do.
But if you are noticing changes (or just a fan of record-keeping) there are better ways of doing this. For example, Cooper recommends keeping a physical or digital document recording the crack's length and any other relevant measurements or observations, like the direction of the movement, whether it's also widening, and so on.
Also, if you notice that the crack is shifting fairly regularly, Cooper suggests making note of the temperature and humidity levels each time it moves to get an idea of whether the changes are seasonal.
When to be concerned about a crack
Though hairline cracks in walls and ceilings typically aren't cause for alarm, it's important to know how to spot the signs of a potential problem, including those that may require professional attention.
Changes in width
According to Korey Gregory, a licensed general contractor and the superintendent of ASAP Restoration, the most important thing to monitor is the width of the crack. "Think of cracks in a home like a windshield," he says. "You almost expect the crack in a windshield to grow in length, but if it started to widen out and let in air while driving, you’d be concerned. Cracks in the walls of your home work the same way."
When a crack grows in width, that means there's been substantial movement, which could be a sign of structural issues. "If a crack grows from more than a hairline fracture to an eighth of an inch or more, I would be concerned and call an expert right away to be safe," Gregory says.
Growth in length
Unlike its width, there isn't a specific length or amount of growth that clearly demarcates when a hairline crack has become a concern, but Cooper says that significant lengthening over a short period could indicate structural movement. As Gregory points out, cracks can get longer for a variety of reasons, including years of doors closing, people walking above that area, kids playing upstairs, or even heavy winds that move the home slightly. But unless these cracks are also growing in width, they're typically not cause for concern, he says.
Location of the changes
When you notice a crack is getting longer, pay attention to the direction of the growth. For instance, according to Gregory, a crack that continues up vertically through a doorway header could be the sign of a problem. Because doorway headers are thickened with supporting beams that tie into the foundation or slab, if you notice that the header is shifting, it means that "major issues are happening with the structural integrity of the home," he says.
Along the same lines, Cooper says that cracks near windows, the corners of a room, load-bearing walls, or where the wall and ceiling meet might also signal settlement or structural issue, and "should raise more concern."
Also make note of the direction of the crack's movement. "Vertical or diagonal cracks are typically less concerning than horizontal cracks, which could signify foundation or structural problems," Cooper says.
Cracks on the walls of the second floor (or above)
Additionally, if there are cracks in the walls of the second floor in a home, then it might be a sign that the builders didn’t follow the proper methods for securing the second story to the first and the foundation. With most two-story homes, the studs from the first floor extend upwards and become the studs of the second floor.
Occasionally, builders will sister in studs on the second floor which aren’t as structurally sound. In extreme weather situations, the studs connecting the first and second floor can act as a pivot point causing stress cracking. As with cracks on the first floor, and above doorways, if the width increases, you should have it professionally checked out.
The shape of the crack
According to Cooper, if what starts out as a single-line crack goes on to branch out or form a web-like pattern, it could be a sign of increasing stress on the structure.
Accompanying issues
When you first notice a crack, check to see whether there are any other new issues, like sticking doors or windows, uneven floors, or gaps between walls and floors, which Cooper says could be another sign of structural problems.
How to repair minor cracks
According to Gregory, the best way to fix elongating cracks that aren’t increasing in width is to use silicone caulking. "The reason for this is because silicone will stretch and shift with the crack, whereas drywall mud will eventually reveal the same crack again, especially if it is growing in width too," he says.
When to contact a professional
For cracks that are widening or growing in a concerning shape, location, or direction, your best bet is to bring in a professional for a thorough inspection of your home. If you're uncertain about the seriousness of the crack, or if it's rapidly changing, Cooper says that it's better to be cautious and consult an expert. Additionally, if you have an older home, or one with a history of structural issues, she says it's advisable to involve a professional as soon as you notice any potentially concerning cracks.
