Best Stud Finder for Lath and Plaster Walls

Modern stud finders typically struggle with lath and plaster walls. The sensors in these devices have difficulty picking up the density differences and the often-thicker construction found in older homes. One writer who tested six popular models found that while some performed better on plaster than others, only one consistently marked the center of every stud.

How the Tests Were Conducted

Tom Gaige built a mock-up wall to evaluate the devices. The setup included a section with single-layer drywall, a section with double-layer drywall, and a section with lath and plaster. A gap separated each section, allowing the testers to see what was behind the surface. Behind the wall sections, the team installed a series of objects to detect, including electrical conduit with live AC. The writer ran each stud finder using standard techniques to determine its accuracy.

The results were converted into percentages to make comparisons easier. The data tracked four specific metrics: on-center detection, off-center detection, missed studs, and false stud detections. The goal was to find which tool could consistently identify the center of a stud and avoid false readings.

The standard technique for drywall involves letting the law of averages work. The user starts in an empty section of the wall and moves the device until it shows a center mark. They then repeat the process from the opposite side to recalibrate. This averaging method improves precision, especially when accuracy is critical, such as when mounting a TV. The writer notes that the process becomes more necessary on lath and plaster walls due to their inconsistent framing. In these older walls, studs may not be spaced at the standard 16 or 24 inches.

For a homeowner trying to hang heavy items in an older home, the challenge is not just finding a stud but confirming its location before drilling. The time spent running the device multiple times on each side pays off when avoiding a pipe or electrical wire hidden within the lath structure.

Top Performers on Plaster Walls

It properly detected each stud and correctly noted the presence of live AC. However, it registered a couple of false stud detections along the way. The writer recommends getting multiple measurements to verify the readings. If the device seems to have more trouble reading one “stud” compared to the others, it may very well be a pipe.

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This model did not miss any studs and had no false stud detections. It is also less expensive than the M210 by nearly $40. The downside is that this model does not have AC detection, which can be an issue for remodeling projects that involve cutting into the wall.

Other Stud Finders That Can Work

However, it did have some misses, and its higher false stud detection rate makes it a less reliable option for plaster. Considering the M70 is also less expensive, it is difficult to justify the HD70 if one works on plaster walls frequently.

DeWalt’s stud finder features a much thinner physical design than most competitors, but it is easier to use than it might initially appear. In the plaster tests, it struggled significantly, missing more than a quarter of the studs and posting a 33 percent false stud detection rate.

Final Thoughts

While other brands can work, the writer found both the M210 and M70 to have superior accuracy for finding studs in lath and plaster walls.

The company claims this model specifically handles lath and plaster. The writer has not had the opportunity to test it yet, but it is on the list for a future update. The device is expensive, costing $119.99, which is twice the price of the M210.