TL;DR
Pro Tool Reviews tested six stud finders on a mock-up that included lath and plaster, finding that performance varied by model. The Franklin ProSensor M210/X2100 detected every stud center in the plaster test and detected live AC, but it also produced false stud readings; the less expensive M70/X700 missed no studs and had no false detections, though it was less precise and lacked AC detection.
Pro Tool Reviews tested six stud finders on a mock-up section of lath and plaster wall and found that the Franklin ProSensor M210/X2100 correctly located the center of every tested stud. The model also produced false stud readings, while the Franklin M70/X700 offered fewer false detections but identified the center less consistently, according to the report.
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The test was conducted on a wall mock-up built by Tom Gaige, with separate sections of single-layer drywall, double-layer drywall and lath and plaster. A gap behind the sections made it possible for the testers to see the objects being detected. Those targets included standard and metal studs, a stud with live AC, electrical conduit carrying live AC, PVC pipe and a water-filled copper pipe.
On the plaster section, the M210/X2100 recorded 100% on-center detection, with no missed studs or off-center readings in the test. It also recorded live AC detection at 100%, but its false stud detection rate was 33%. Pro Tool Reviews says the extra false readings mean users should take multiple measurements rather than assume every signal marks a stud.
The M70/X700 recorded 67% on-center detection, no missed studs and no false stud detections. It was listed at $21.99, compared with $59.99 for the M210/X2100. The M70/X700 does not detect AC, the report says. Other tested models included the Zircon HD70 and JAXWQ 139-FYELLOW; both had a 7% missed-stud rate, while their false-detection and on-center results differed.
Choosing a Finder for Plaster
The results matter to people installing shelves, cabinets or a television mount in older homes, where lath and plaster construction can make electronic stud detection less dependable than on drywall. A misplaced mark can lead to a fastener missing the framing, while a false reading can send someone toward a pipe or another object behind the wall.
The report does not establish that one tool will perform the same way in every home. Its findings point instead to trade-offs: the M210/X2100 had the strongest center-location result in this test and detected live AC, but it also generated false stud signals. The lower-priced M70/X700 avoided false signals in the test but lacked AC detection and was less consistent at identifying the center. Users should weigh those differences against the job and verify readings before drilling or cutting.
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How the Wall Test Worked
The report describes lath and plaster as difficult for stud-finder sensors because the wall can be thicker and its density varies. Even on drywall, the reviewer says, stud finders can mark an edge as a center, miss framing or indicate a stud where there is none. A typical stud presents a target about 1½ inches wide, though framing in older homes may vary.
For its comparison, the reviewer tested each finder using repeated readings from opposite directions, then converted results into percentages. The report defines on-center detection as correctly locating the center, off-center detection as identifying an edge as the center, missed studs as targets not identified, false detections as other objects flagged as studs, and AC detection as correctly noting live electrical current. Those categories describe the test’s results, not a guarantee of performance in other walls.
The reviewer recommends letting a device reset or recalibrate between passes and comparing marks from both directions. The report also cautions that stud spacing in lath and plaster walls can be inconsistent, so measuring a standard distance from one detected stud may not reliably locate the next one.
“It properly detected each stud and properly identified the live AC.”
— Pro Tool Reviews, on the Franklin M210/X2100
Limits of the Test Results
The supplied report gives results for six tested models but only includes detailed figures for the Franklin M210/X2100, Franklin M70/X700, Zircon HD70 and JAXWQ 139-FYELLOW. It does not identify the other two models or provide their results in the supplied material. It also does not give the number of test passes behind each percentage, so readers cannot assess the sample size from the information provided.
The results are from one mock-up wall, not a broad survey of homes with different plaster thicknesses, lath types, repairs or framing layouts. The report does not establish how the tools perform across those conditions. Its listed prices are report figures, and current retail prices may differ. The M70/X700’s lack of AC detection is stated, but the supplied material does not give AC-detection results for every tested model.
Verify Before You Fasten
The report’s practical recommendation is to repeat readings from opposite directions, allow the finder to reset when needed, and look for agreement among marks before choosing a drilling point. If readings conflict or a signal behaves differently from nearby framing, the reviewer says it could indicate another object, such as a pipe. The report does not describe a planned follow-up test or additional results.
For projects involving a wall opening, the test’s AC-detection figures should not be treated as a substitute for checking what is behind the wall. The M70/X700 does not offer AC detection, and even the M210/X2100 produced false stud readings. Readers should confirm the wall’s contents and use appropriate precautions before drilling or cutting; the supplied report does not provide a separate safety protocol.
Key Questions
Which tested stud finder performed best on the plaster section?
The Franklin ProSensor M210/X2100 recorded 100% on-center detection in the test and detected live AC at 100%. It also had a 33% false stud detection rate, according to Pro Tool Reviews.
Was the less expensive Franklin M70/X700 more accurate?
It was less consistent at locating stud centers, with a 67% on-center rate, compared with 100% for the M210/X2100. The M70/X700 had no missed studs or false detections in the test and was listed at $21.99, but it does not detect AC.
Can these results guarantee a finder will work in my home?
No. The report tested the tools on one mock-up wall. Differences in plaster thickness, lath and framing may affect results in other homes.
How did the reviewer recommend checking a stud reading?
Pro Tool Reviews recommends taking readings from both directions, allowing the finder to reset or recalibrate as needed, and comparing marks. The report says repeated measurements can help narrow down the center, especially on plaster walls.
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