Door mags to existing wall/door

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Mountainbikeak

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I’m on a job where we’re adding 120 volt door mags to several exsisting doors and walls. Originally I wanted to just add cut in boxes, but after thinking about it, cut in boxes with battleships aren’t going to hold nearly as well as I would like. Can someone with experience share what’s worked for you? I would like to avoid completely opening up the wall if possible. Thanks!
 
Welcome to the forum. There are a few different options for door mags. I'm presuming you want to use the type that hold open a door, and release it upon loss of power or signal from the FA system, something like this:

https://www.rbadoor.com/sem7840-lcn...MI9JDUruzF2AIVmbjACh1lBAnfEAQYBCABEgLxhfD_BwE

The only way I know of to rigidly mount the electrical box to ensure it can withstand the pulling force on it is to cut the wall stud to stud and mount a box bracket like this:

PH3720m.jpg

https://www.erico.com/category.asp?category=R938#catalog-applications

If the wall you are mounting the box to is a fire wall, I dont think you could use a cut in box even if you wanted to. and make sure if this is a fire door that it is tied to the FA system properly.
 
Mountainbikeak said:
I’m on a job where we’re adding 120 volt door mags to several exsisting doors and walls. Originally I wanted to just add cut in boxes, but after thinking about it, cut in boxes with battleships aren’t going to hold nearly as well as I would like. Can someone with experience share what’s worked for you? I would like to avoid completely opening up the wall if possible. Thanks!
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Determine the exact location of a stud. You can do this with a stud finder from any home center. Since studs are normally spaced at 16" on center. . . a regular 32'" or 36" door would be within the mounting "window" of the magnet half of the door holder.
I installed one in my garage where the door is self-closing (spring loaded) . . .it helps in holding the door open when unloading groceries.

Self-closing garage door is required and most of them are fire-rated. I don't know what your situation is and you probably know what limitations are in regard to doors.

I'm not sure if my install is a violation but at least it keeps my wife happy not having to struggle when unloading groceries.
It is no different from jamming the door with a wedge--it's hard on your back.

BTW: If you are doing this from a 120 V source you still need to open portion of the wall to provide power unless there is already one there.
 
These door mags were added late in the project, while half of them were roughed in before Sheetrock went in the other half (which was added later) is in a finished wall. Unfortunately, it looks like the general will have a patch late in the project!
 
Mountainbikeak said:
These door mags were added late in the project, while half of them were roughed in before Sheetrock went in the other half (which was added later) is in a finished wall. Unfortunately, it looks like the general will have a patch late in the project!
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Drywall is pretty cheap to patch, it's usually just the idea of cutting into a finished wall that puts people off. If there is still painters on the job then there is reason not cut and patch.
 
Mountainbikeak said:
Good point!
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Sheetrock maybe cheap but it is the guy doing the patching that's going to raise the GCs eyebrow.
I don't know about your area but here in CA., construction workers across all trades are paid $45 an hour.
And people wonder why homes cost so much in LA and vicinity.
If this is an agreed upon extra work where the man-hours spent is shouldered by GC then you don't have to worry about it.
 
myspark said:
Sheetrock maybe cheap but it is the guy doing the patching that's going to raise the GCs eyebrow.
I don't know about your area but here in CA., construction workers across all trades are paid $45 an hour.
And people wonder why homes cost so much in LA and vicinity.
If this is an agreed upon extra work where the man-hours spent is shouldered by GC then you don't have to worry about it.
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I was hoping to use a cut in box to eliminate the need to patch... the general has been really good to work with, but in the end I’ll be offering the owner a better end product if I cut out enough rock to properly install a j-box.
 
Mountainbikeak said:
I was hoping to use a cut in box to eliminate the need to patch... the general has been really good to work with, but in the end I’ll be offering the owner a better end product if I cut out enough rock to properly install a j-box.
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I agree with you, a cut in box ain't gonna cut it. I've replaced more than one door holder that someone else tried to use a cut in box.

The one time I did it without cutting open the wall I used a ceiling fan remodel kit. It worked really slick, but it was more than a couple hours work on site, plus a couple custom parts fabbed up at the shop.
 
Mountainbikeak said:
I’m on a job where we’re adding 120 volt door mags to several exsisting doors and walls. Originally I wanted to just add cut in boxes, but after thinking about it, cut in boxes with battleships aren’t going to hold nearly as well as I would like. Can someone with experience share what’s worked for you? I would like to avoid completely opening up the wall if possible. Thanks!
Click to expand...

It is better than 50% odds that the wall the door holder needs to go in is a rated fire wall. You can't cut in a box in a fire wall. More accurately the box has to be secured to a stud.
 
Mgraw said:
Don't they make surface mounted back boxes for magnetic door holders?
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The problem still remains of how to support that surface mounted box if there is no stud directly behind it.
You could use a piece of plywood between studs and surface mount the box to it, or use a metal plate, but either would be ugly.
A large problem is that there will be substantial pull on the holder as well as significant impact when the door is opened to engage it.

Trying to fine tune another door stop to prevent impact but allow solid magnetic contact is problematic to say the least.
 
What about using floor mounted holders? Is that possible for your construction?

ABH-2600-525.jpg

Their web site is here.

I thought about that too, but running wires through the floor without planning could be even worse than through a finished wall.
I suppose you could surface wire a few inches to the wall, behind the door where it would not be too exposed. ]

I also wonder whether you could change out one hinge to electrical feed through and put the coil unit on the door. (Still have to figure out how to solidly mount the other half to the wall, but you could floor mount that!) Might not be described as an option in installation instructions though.
 
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