Garage ceiling mounted box rail - add a stud in between or direct to ceiling?

[devilish]

Background: Need to attach 2x 30 foot box rails to the ceiling to be able to have bypass barn doors. Will have (4 count) 8x10 (WxH) barn doors hanging from it. My joists run front to back of the garage, and above the garage is a small attic (unused) and a sloping roof right above. There is about 5+ feet of clearance in that mini-attic so I can access the area above the garage ceiling via a slim attic door to ensure all my screws are right in the middle of the joists.

Since the joists go front to back of garage, I think the load should be evenly spread and not a concern to take the weight of the doors. The question is how to attach the box rails?

Option A: Drill holes in the box rails, and attach with 3 inch structural screws directly to the ceiling. I think this screw will work - https://www.aftfasteners.com/grip-r...rews-hex-washer-head-black-50-box-grsshw10350. Or worst case, similar screws but without the washer head.

Option B: Attach a 2x6 to the ceiling first using the same structural screws. The advantage is that I can screw 2x per joist on each side of the 2x6 giving it extra strength. And then, I can screw the box rail into the 2x6 with 2 inch screws.

What would you do?

Any alternative suggestion on screws to use?

 

[BillK]

How heavy are the doors ? What do the instructions for the rails suggest ? What you are proposing sounds like overkill to me but I dont know how much weight you are talking about.

 

[billconner]

I'd look for some slotted angle or similar, attach both tracks to it with bolts, and put a fastener through the other leg into side of joist (not in that order). Sort of like picture, which you could use and just drill through triangle part. I'd guess the track only needs to be supported every 4' or so.

 

[johnre]

Same situation for me, except the box rail had to mount to a vertical wall, not a ceiling. And I first mounted my box rail mounts to a 1 x 6, screwing them solidly in from the back with 7/16” carriage bolts. Then I screwed the 1 x 6 to the wall framing, hitting every single joist at both the top and the bottom with a 3.5” X 10 construction screws.

Box rail mounts looked like this:

Modal: National Hardware

www.national-hardware.com

Think of the heavy mass of a door hitting a stop; that transmits a pretty hard jar onto the box rail and the mounts. You don’t want to be using too few fasteners here.

 

[carlaisle]

Are these doors are being installed inside where there is a solid floor? If you put wheels on the bottom all of the weight can be removed from the box rails so all they need to do is serve as guide rails.

 

[billconner]

Let's look at weight. 4 @ 7.75 x 9.75 X 4 PSF (double 3/4 ply - worst case) is 1200 pounds in a 900 SF (30X30??) garage is 1 1/3 PSF - insignificant to the roof and attic loads.

I've design a lot of big things that are tracked - some many thousands of pounds - and would always prefer hanging. As far as bearing weight on the floor, now the doors have to stay vertical so they have to be stiffer than if hanging and in tension. A thin piece of material will need a lot of framing to stiffen it and keep it from bowing. Also much easier to get suspended track level and straight than floor. And if it's wheels on floor, you really need an embedded rail and flanged wheels (which is what I do when I can't suspend something).

Keep it simple and keep it light weight.

 

[johnre]

I've design a lot of big things that are tracked - some many thousands of pounds - and would always prefer hanging. As far as bearing weight on the floor, now the doors have to stay vertical so they have to be stiffer than if hanging and in tension. A thin piece of material will need a lot of framing to stiffen it and keep it from bowing. Also much easier to get suspended track level and straight than floor. And if it's wheels on floor, you really need an embedded rail and flanged wheels (which is what I do when I can't suspend something).

Keep it simple and keep it light weight.

^ This. And on top of all that was mentioned, you want it to roll smoothly and with lowest friction for easy opening and closing. Putting down wheels to a floor detracts from both.

Furthermore, my floor is sloped in the direction of door travel. The only way to keep it traveling completely level is to hang it.

The National Hardware trolleys and box rails that I used are rated at 225 pounds each. Both together can carry 450 pounds. My door is considerably lighter than this, perhaps 100 pounds, and it can be started moving with a single finger push. There’s a lot of inertia once it starts moving, so once it’s started, it’s just a matter of catching it and stopping it at the end of the travel.

 

[billconner]

For the beast of a door, Richards Wilcox is hard to beat. For most I've used H&H Specialties. Occasionally Unistrut. I find all 3 have good engineering back up.