I have a fire alarm job coming up where I'm adding magnetic door holders. A few years ago I was given some cut in boxes to use on walls with wallpaper and they didn't turn out so smooth. Any suggestions on how to re-enforce cut-ins so they hold up to the magnetic vs door closing pulling force? Thanks guys.

A few years ago we retrofittied dozens of apartment buildings with door mags to isolate the elevator shafts. Nothing we tried on the walls held up good unless you caught a stud, we switched to floor mount mags and the problem was solved.

I agree, the floor is a good way to go. Other than cutting open the wall and framing to support it.

Well i may get flamed for this but...We have on occasion filled the wall space with white silicone caulking (the outdoor type).After the box was installed with f clips.Inspection never had a problem with it as long as it didn't get it in the box and it looked nice with the gaps filled in.Once it cures if it does come out a big chunk of wall has to break around it.
Unless you are working with block go with the floor magnets because people will also be pounding the box back into the wall when they try to reopen the doors after the alarm is reset.If the bolt that holds the Knuckle is lose the plate will slide sideways and they will stand there slamming the door against the magnet until they finally see they they have to line it up.Funny to watch a PITA to fix.
cheers


[This message has been edited by frank (edited 03-22-2006).]

We just did this for 30 doors in a 15 story apartment building.

We open the wall and put blocking in. If the customer does not want this we pass on the job.

We are not going to get stuck warranting the work that is sure to go bad.

I have not seen floor ones, I will keep that in mind.

What about the door closure type ? Where the magnet is in the closure. I have worked with 2 types like this
Type 1 was recessed in the frame and we drilled a 1/2" hole straight up through the frame and fished wire down to it.
Type 2 was were the closure was mounted on the face of the frame. I was able to run wiremold down the face of the wall to the closure.
It does cost more but it sure beats tearing open finished walls.