Garage Door Inspection: DASMA guide

I’m updating the InterNACHI Narrative Library Garage Door Inspection section and thought I’d pass along the Door and Access Systems Manufacturer’s Association (DASMA) PDF checklist upon which I base my comments for inspecting garage doors.


Good! Please tell people to stop reverse testing by shoving on the bottom of the door in the close cycle and perform the test the way the doors and operators were designed to be tested.


Specific guidelines that you can refer to. Great concept. I’ve gotten some great videos of the 2x4 failure to include in my reports.

I don’t know what you mean by “shoving” but I’m going to guess that we are going to disagree. The 2X4 test should only be done after the opener passes the “hand” test per almost, if not every, manufacturer’s instructions. After having four garage door assemblies self destruct on the block test in my early years, I now only do the hand test. (Where you grasp the bottom of the door within a couple of feet of the floor and apply approx. 20lbs of resistance) I have a disclaimer in my report explaining the block test and the hand test. A few years ago, some insurance group did safety testing and determined that the block test was not a real world test and recommended a roll of paper towels. They did not specify a brand, but I think Brawny works well. (Yeah, my tongue is in my cheek, but only a little).
And did you guys note the typo in the DASMA TDS…they have 2’X4’, not 2"X4". A 2 foot by 4 foot block would be a hefty piece of wood to tote around.

Then your visual inspection method is pretty deficient and you’re an incredibly slow learner if you destroyed four doors through faulty testing methods.

Since the Manufacturer’s testing methods reflect DASMA testing methods (DASMA is the manufacturer association) and DASMA testing methods reflect those that are mandated in 16 CFR Part 1211 - SAFETY STANDARD FOR AUTOMATIC RESIDENTIAL GARAGE DOOR OPERATORS, none of which call for shoving on a door in the closing cycle by hand, yet all of which specify a solid object of between 1 and 2 inches. I don’t think you can support your claim with an actual authoritative reference. - You won’t find a reference to pushing or shoving on a door (this is how inspector break them)

Every label shipped with every door operator manufactured for use in the U.S. since 1993 includes this specific language “Test Door Operator Monthly: Use a 1 1/2 inch thick object placed on the floor under the closing door. In the event the door does not reverse upon contact, adjust, repair, or replace the operator.” while every door operator manual includes the following “Test door opener monthly. The garage door MUST reverse on contact with a 1 1/2 inch object (or a 2 by 4 board laid flat) on the floor. After adjusting either the force or the limit of travel, retest the door opener. Failure to adjust the opener properly may cause severe injury or death.” Why? because it’s part of the federal law that I cited above.

Every door and every door operator manufactured since 1993 has been specifically engineered to be tested in this manner. Doing anything else is a non-standard test method (there are some minor variations in some specific state regulations). Do a search in these forums and you’ll find numerous instances of inspector breaking doors because they shoved on them, which puts downward force on the top panel of the door when it’s in a horizontal position, which causes the panels to fold.

I’ve performed pressure reverse testing on 10s of thousands of garage doors and never broken one in the process.


I’m afraid I’ll have to agree with Chuck on this one.

It’s OK to agree with a Member Of The Year!
Don’t be afraid or scared. :cowboy_hat_face:

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The 2x4 test is actually only a contact reversal test or entrapment test. (See DASMA document).

NC requires inspectors to verify that the door will reverse with a reasonable force so you have to develop a good test procedure for yourself and explain it in your report.

A 2x4 will NOT tell you anything about the force reverse level. Why?
Because the system only cares about preventing entrapment during the last few inches of travel. Yes, I have talked to the manufacturer. Do the 2x4 test if you want but please don’t tell the client the door has been fully tested.

All newer openers have mapped friction into memory with added amounts to overcome normal roughness in the track system. They use speed detection on the motor shaft to calculate friction/force. This in effect provides a decent level of force reversal.
The older openers with adjustments available for force levels are more likely to have force problems.

I suggest saying in the report body that no opener is fully safe for all persons/ages because that is also a fact.

There is an old DASMA document that had an artist rendition of a picture of a person putting their hand under a garage door at waist height. I bet the lawyers made them remove it.
Same thing for the manufacturers, they are not going to suggest that anyone put a body part under a moving door so there is no force test required by anyone except NC and whichever other states that copied it.

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Bruce, how do you test the automatic reverse feature?

There are three reversal tests, sensors, 2x4 test and force reversal.
I disclaimed the 2x4 test because it was not required in NC. I reported that it is to be done by the owner every month and damage could occur.
I only did the force reverse if the door was in very good condition and no car under it.
It takes special practice and ability to estimate 10-12 lbs of force. I’m not here to teach the technique for liability reasons. FYI the newer openers reverse around 5-6 lbs of force, very smooth and nice. The older systems will get false force trips if not set to around 10-12 lbs.

Thanks Bruce! Good clear answer!

Newer inspectors pay attention to guys who’ve obviously done their homework like Chuck and Bruce, and then use your best judgement. What works best may vary by jurisdiction.

I’ve been pretty busy this summer, so I’ve haven’t had a lot of time to respond. You can judge if I offer a reasonable response to your reliance on DASMA guidelines and not to mention, your kind comments about my competency and learning abilities. Although I don’t think I can match your “tens of thousands”; in my twenty plus years of inspecting, I’ve operated a few door openers here and there. In my younger years working construction, I assembled some garage doors and installed many openers.

Regarding DASMA, TDS #167 states “in some rare cases, this (2X4 block) test has damaged the door system when the operator’s force-setting has been improperly set”. Lucky me, I found four of those rare cases in my first few years. I’ve heard many inspectors relate similar experiences with the 2X4 test. So, no big surprise that many if not most His don’t do any contact sensor testing.

The CPSC addresses this force-setting issue with a 1 7/8” diameter cylinder placed in the path of the descending door with reversal adjusted to 15lbs of downward force. The federal guidelines don’t address force but instruct that the opener should reverse after two seconds of contact. And in variance to DASMA and the CPSC, the fed uses a solid object that is 1” high and “A solid object is to be placed on the floor of the test installation and at various heights under the edge of the door” (emphasis is mine). The fed finishes by requiring monthly testing with a flat 2X4.

Randomly picking a manufacturer, the Liftmaster manual instructs to set the down force by grasping the door bottom about halfway through the down travel. (I’ve never heard of nor read anything calling for pushing or shoving on the garage door.) If it doesn’t reverse with this grasp (hand) test, then adjust the settings until it reverses. Only when it responds to the hand test, should the flat 2X4 be utilized. I’ve seen similar instructions with other manufacturers.

A further benefit of the hand or grasp test is that it provides some indication of what the down force is. I’ve had doors grind down on the block before reversing. That might satisfy DASMA but pity the poor kid or kitty under that door. A study by some St. Paul doctors back in 1996 found that 72% of tested openers reversed after exerting forces over 130lbs which they found to be enough force to cause serious injury. My own observations are that older units are more likely to exert excess force. Openers made in the last ten or so years tend to have more responsive safe guards. Curiously, TDS#167 is silent about determining downward force.

I suggest that Liftmaster’s instructions are applicable for us because we rarely know the history of the door system. And as DASMA admits to the risk of the block test on an improperly adjusted opener, that is arguably an admission that their TDS #167 checklist cannot reliably predict an improperly adjusted opener that is exerting dangerous force prior to using the flat 2X4 test. The hand or grasp test gives an indication of the down force without risk of the opener trying to pinch that block of wood in half.

As with anytime we go beyond our SoP, then we should do so within our expertise, comfort, and competency zone. That will be different for all of us.

Standards aside, although they might apply in court, if the purpose of testing is to protect children and small animals and that’s why the photosensors are set at 6 inches maximum off the floor, then that’s the crucial height. A child’s head… a poodle.

My understanding is that, the closer a door gets to the floor, due to mechanical advantage a correspondingly increasing amount of force is required to make it reverse, and so the amount of force required to make the door reverse is most important at the 6-inch level above the floor, not the 30-inch level, or the 1.5-inch level.

It seems to me that the most logical way to test garage doors would be to measure the amount of force required to make the door reverse at 6-inches off the floor.
Handheld scale, bathroom scale… not hard to do. Does this not make sense?

The trick is getting any credible organization to take a stand on the level of pressure that might cause damage. A little cadaver testing and we’d know just what was needed. Or maybe poodles would suffice!

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