Fix for a 18' wide sagging garage door

pattenp · Jan 26, 2009

I have an 18’ X 8’ garage door that when opened you could see that the top panel sagged in the middle even with having a 4 inch wide stiffing strip. Over time the top panel kept the bow and when the door was shut there was about a ¾ inch gap between the center of the top panel and the top weather strip. I know the easy way to take care of the problem would be to bow the weather strip to close the gap but I have this thing about stuff being visually straight. So my solution was to create a tension truss so to speak using a 3/32” cable. The cable is connected at both ends of the stiffening strip and then held out at the center by a short piece of metal channel. I put in a turn buckle to tighten the cable across the top of the door to keep the door flat when closed. It works well, so I just wanted to share this others who may have this same issue with a wide door.

rinker1 · Jan 26, 2009

Great idea, that's a common problem with wide doors, I've even seen it in 16 ft wide doors.

krooser · Jan 26, 2009

I had an 18X8 built for my new garage in 1975. the door was of a wood-composite construction. I lived there for about 8 years and never noticed any problems.

But your solution seems to be the correct answer.

dannykester · Apr 14, 2012

Genius! I hope you don't mind if I copy.

Danny

lilredex · Apr 14, 2012

The miracles of triangles. Have a newer 17 Ft. door and it is OK for now, but that is the best method for correction of the sagging problem.

I have a couple of wooden tool shed doors that have bowed out at the bottom and no longer close flush. Was thinking of running a 1 X 3/8" (spring) bar diagonally with a 2 X 2 piece under it, close to the top, then pulling it in at the bottom with a carriage bolt (to pull the bottom in).

Had toyed with an idea such as your method, but it won't work in my case.

Thanks for sharing.

AndyL · Apr 15, 2012

Interesting - how many teks in that truss? Is the flange mounted correctly down to the door skin?

I've seen some minimal bow in glazed 9100's before, but that's a bit excessive...

upndown · Apr 15, 2012

Good thinking pattenp!! curious to see how that works for you. The Foamcore door with a glazed top always had a sag to it.. just not noticeable with a ceiling hung operator because with the door closed the operator arm would push the top section tight against the header. good luck! :beer:

Mr onetwo · Apr 15, 2012

What a great idea!I have a 16' WD 8500 with no windows and it has about a 3/4" bow after 3 years.I just switched to a 3800 opener and the gap is very evident.I will be trying this fix for sure! Thanks very much for the tip!

Morrisman · Apr 15, 2012

Could you not fit some sort of 'ramp' or ledge device fastened to the roof so that when the door is open it slides into the ramp and is held up?

Steevo · Apr 15, 2012

I think it's funny to see this "idea" being used on a modern metal door.
This is how garage doors were made for fifty years or more, when they made them of wood.

n2ocamaro · Apr 19, 2012

Since I have been working on my garage and being up on a ladder a lot, I noticed my 16' door sags in the middle. Putting this on my to-do list. Seems like the more work I do, the more problems I find!

bowmard · Apr 20, 2012

Sixteen foot garage door headers will sag over time. I've seen it on several garages built by local garage builders. I personally wouldn't have a 16 foot because of the sag problem The two new garages I had built over the years have 7' x 9' doors. A coworker built a new garage, and he wanted the 16' door. Knowing of the sag problem, for the header build-up, instead of using the normal 1/2" plywood spacer between the two 2x12 header planks he built up a fabricated (welded) truss from 1/2 steel bar stock. I believe it was 1/2" x 2". Careful attention was paid to weld sequencing so that distortion was minimal, if any at all. He then built up the header on the floor and called an army of friends over to help lift it in place. That garage is over 20 years old and the door header does not sag at all.

pattenp · May 22, 2012

The problem I had was not a sagging header, it was the top door panel had a bow in it. My 18' header is made up of two 20" LVL beams with a story above, no sag what so ever.

Oh.. and my cable truss to flatten out the door when closed is still doing it's job very well.

bowmard said:
Sixteen foot garage door headers will sag over time. I've seen it on several garages built by local garage builders. I personally wouldn't have a 16 foot because of the sag problem The two new garages I had built over the years have 7' x 9' doors. A coworker built a new garage, and he wanted the 16' door. Knowing of the sag problem, for the header build-up, instead of using the normal 1/2" plywood spacer between the two 2x12 header planks he built up a fabricated (welded) truss from 1/2 steel bar stock. I believe it was 1/2" x 2". Careful attention was paid to weld sequencing so that distortion was minimal, if any at all. He then built up the header on the floor and called an army of friends over to help lift it in place. That garage is over 20 years old and the door header does not sag at all.

Big-Foot · May 23, 2012

Nice job! I like the sensor location..

pattenp · May 23, 2012

The sensor was to prevent the door from being opened when I had a car on the lift. The sensor is now long gone because the door has been converted to high-lift.

Big-Foot said:
Nice job! I like the sensor location..

Big-Foot · May 23, 2012

pattenp said:
The sensor was to prevent the door from being opened when I had a car on the lift. The sensor is now long gone because the door has been converted to high-lift.

Good idea and will be swiped by me for my shop door on the lift side..

pattenp · May 23, 2012

Here where I got the sensor. http://www.walkeremd.com/Banner-Eng...e-ra-q45.htm?gclid=CNudhMyLl7ACFcyb7QodCwTl2g

Big-Foot · May 23, 2012

Thanks... Might be a way to use the original closing sensors for this task as well.. Run the outputs through a flip-flop and trigger a relay? Been away from the tech bench for a while, but I think I would be able to cook something up...

TC-Tex · May 27, 2012

Genius!!! I'm going to do this today!

patrickoneal · Apr 17, 2016

You're the man pattenp. I was having exactly the same issue with my 16' door. I've attached a photo that shows a little more detail on the C-channel, I'm not sure if you did it the exact same way. I used an aluminum channel from lowes that was labeled as fitting the edge of 3/4" plywood. It barely fit around a bolt head that was right in the way, but it was the biggest they had at the store.

I drilled a 1/2" hole all the way through the channel, and then cut it right in the center of the hole to make an indentation for the cable to set in. The overall length is about 8" from the end to the bottom of the indentation. This proved to be a good idea when I initially turned the turnbuckle the wrong direction and it came loose. I was able to put it back together and stretch it over onto the channel.

Before I did this, I could see light coming through a ~1/2" gap at the center of the door, extending several feet in either direction. Now it's nice and tight all the way across.

A couple of questions:

1. Have you had to periodically tighten yours up over the years?

2. I had to crank down pretty good on the turnbuckle to pull the warp out. Have your fasteners held up? I used #12 self drilling screws long enough to go through both sides of the reinforcing strip to attach the cable ends and the c-channel, but I worry a little about the shear strength where I screwed down the cables.

Thanks again.

waywardtom · Jul 7, 2016

greetings,

have this problem with my 16' garage door, the sagging in the middle of the panels.
have inquired with local hardware stores (Lowes, Home Depot, a couple independent garage door on site repair companies), where to purchase this particular lengthy beam which can be seen in the attached photograph; but no one knows. any ideas?
thank you.

Ratchet Thunderstud · Jan 8, 2017

I apologize for resurrecting such an old post, but...

What a great idea!!! I registered just so I could post a bit THANK YOU to the original poster. I hope to repair my sagging 16' garage door tomorrow using this plan, and will post a photo of the repair if I can figure out how.

I installed a 5 kW heater in the garage a couple years ago. The gap at the top of my garage door is bad enough that the heater has been running constantly in this cold weather. I estimate it costs about $12 for every 24 hours the heater runs. The ROI on this repair will be very short.

Thanks again "pattenp"!

EricNord · Sep 22, 2017

I've got an 18' wooden door that is 45 years old and this may be just what I need.

Hot Rod Grampa · Sep 23, 2017

The part you ask about is a strut. It can be purchased from any door company in about any length you need. The repair to the door in the op is how wide doors were done long ago. The steel rod(back then it was not a cable) was attached to a bracket on each side that resembled a angle iron that was screwed to the side of the door mortised into the wood so as not to interfere with normal operation. Good thread.

Slednut · Sep 23, 2017

That is a great idea, when my dad was alive he had an 18x8 wood door, if he was going to leave it open for an extended amount of time he would prop it up with a 2x4.

PT Doc · Sep 24, 2017

Had the same problem on a new steel door and the 8500 opener. Top panel was taken off and placed on two saw horses at the ends. It sagged now the other way and a commercial wind brace was installed with 2 plastic spacers in the middle, one spacer at the quarter mark and no spacers at the ends. This worked great and the door seals great now.

pattenp · Sep 25, 2017

I haven't kept up with this post. I'm glad to see it has been a help to a few people. The tension cable solution is still working well on my door and haven't had any need to tighten the turnbuckle further since being originally installed.

lakeroadster · Nov 8, 2017

Well done pattenp.

b4z · Nov 9, 2017

I used to work in a new construction neighborhood in the '90s. every single header for the 16' garage doors sagged. Where the floorplans were $60K more expensive they used 18" tall Lam beams. 0 sags. the doors were another matter.

pdq925 · Jan 5, 2018

Dang this is a good idea. I'm gonna give it a shot!!!

astroracer · Jan 5, 2018

This is what I did on my sagging 18':
http://ddmgaragedoors.com/parts/struts.html
Added two of them, one to the top panel and one to the next lower panel.
No more sag. I installed them with the door closed and clamped in position.
Mark

Bluevista · Jan 5, 2018

Hot Rod Grampa said:
The part you ask about is a strut. It can be purchased from any door company in about any length you need. The repair to the door in the op is how wide doors were done long ago. The steel rod(back then it was not a cable) was attached to a bracket on each side that resembled a angle iron that was screwed to the side of the door mortised into the wood so as not to interfere with normal operation. Good thread.

x 1

I worked on plenty of houses with old garage doors like that, just like wood step ladder step's wire braces.
Good thinking though, great minds think alike. :thumbup:

On the sagging garage door headers, didn't they use steel flitch plates?
I did plenty of them in the 90's and they never sagged...that I know of. Somehow making those headers up became my exclusive job because I carried a socket set and wrenches in my truck.

kbs2244 · Jan 5, 2018

If you need it or not will depend on how much time the door spends open.
If it id closed there is no weight causing sag.
If it is open the weight will create a sag bend.

Fix for a 18' wide sagging garage door

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