How To Level Your Garage Door Floor (in 15 Steps!)

When your garage door at home goes off level, it can let in an unsightly amount of snow, pests, leaves, or other unwanted creatures or items. Knowing how to level your garage door is crucial to correcting issues with things getting in under one side of the door.

The most common method to level a garage door involves resting the undone garage door onto wooden blocks, making the necessary adjustments, and then re-attaching again. There are important safety concerns than simply leveling the door that need consideration before any repair is to be attempted.

I’ll walk you through the safety concerns you need to check to find out why your garage door suddenly went out of level in the first place. There could be a serious safety issue lurking in the shadows that might need your attention before we level the door.

Once we’ve walked through our safety list, I’ll proceed to give you step by step instructions for leveling the most common type of garage door – the torsion spring counterbalance sectional garage door. Stick around, I’ve got years of experience coming your way.

Safety Concerns About Sudden Garage Door Off-Level Events

Before you start cranking on nuts and bolts, it would be best if you observed a few safety precautions. Take note of the following…

• Always wear gloves and safety glasses for all repairs or maintenance to your garage door. Extreme caution is mandatory, there are a lot of dangerous parts. If you are not comfortable, call a professional.
• Torsion spring counterbalance assemblies that hold a lot of torsion spring force need extra caution. The force is strong enough to lift most of the door’s weight. That’s usually more than enough to break a person’s bones, so use extreme caution or better yet, call a professional.
• Inspect the following for damage or corrosion:
  • Bottom brackets where cables attach to the bottom of the door. Located in the bottom left and right corners of the bottom panel. The cables attach to the outer bottom corners, typically via a metal post and pin with an end of the cable crimped into a loop around the small post. This assembly is fast to rust, being at the bottom of the door. However, it carries the weight of the door. If rusted, the parts should be replaced after removing spring tension. NEVER undo or try to unfasten the cables or bottom brackets while tension remains on the springs!
  • Cables should be inspected and free of burrs, damage, and rust. If they are not in good condition, they should be replaced after removing tension from the door.
  • Cable drums, located above the door, on either side, mounted to the spring shaft. These drums are the assemblies that the cables wrap around. The drums should not have any cracks or damage. Pay close attention to two things in particular:
    • The cable mount point should be in good condition.
    • The ridges between where the cable lies on the drum should not be sharp. To check this, use EXTREME caution. These ridges can become extremely sharp and easily slice your fingers open. To test, I like to use a piece of paper. Wearing leather work gloves, rub the paper firmly along the ridges on the drum. If the paper cuts, the drum is sharp. If the drum is sharp, it can cut and damage the cables, so the drum should be replaced.
  • Springs should be checked without touching them. Inspect the cones on either end of the spring(s). The cones should not be cracked or damaged. If they are, call a professional to come and repair/replace the springs.
  • Shaft assembly is the entire shaft and bearing plates that mount it. Check all mounting locations to ensure they are firmly mounted and secure. All wall mounting plates must be secure prior to you beginning any repairs.

With these safety concerns ticked off the list, let’s get into a step by step instruction on how to actual level your garage door to the floor…

15 Steps To Level Your Garage Door To The Floor

Use extreme caution when working on your garage door. Many parts are dangerous and the springs hold torsion energy that can seriously hurt or even kill you. If you aren’t comfortable working on this equipment please call a professional.

What You’ll Need:

• Step ladder
• Winding Bars (to suit your springs’ winding cones, usually ⅝” x 16” long is sufficient, cold-rolled steel preferred)
• ⅜” Wrench or similar sized adjustable for set screws on drums or springs (if necessary)
• 3 Sets of clamping pliers. I like to use the Irwin Vice-Grip brand.
• 2 pieces of wood, equal in size. I use a couple pieces of 2” x 4” at 6” lengths.
• PPE (gloves, safety glasses are mandatory, steel-toed boots and a hard hat are wise additions)

There are a few ways to adjust the level of the door, assuming something merely came loose. Each method is based on a particular setup.

If there is a center coupler on the shaft, you can slip the coupler to bring one side up or down. This is more common with commercial doors, but isn’t unheard of in residential. Due to the rarity, I won’t cover this today.

If the door is standard lift (It sits vertically, then rises, passing through a radius in the track and ending in a horizontal position), you will be able to do a maneuver known in the industry as slipping the drums. This is the method I’ll be teaching you today as it is the most common scenario. Here are the steps:

1. Inspect the door thoroughly, including the points noted above.
2. Assuming all passes inspection, note which side of the door is higher, or which side is lower. If one side is too low, the cable on that side will be loose when the door is closed. If one side is too high, you will see a light gap under that side and neither cable will be loose.

Note the amount of height the side of the door needs to either go up or down, depending on the situation.

Note: A properly set sectional door will never have loose cables, even in the closed position.

3. If you have a door opener, disconnect the power, and disconnect the opener from the door. Usually this is a J-shaped arm attaching to a bracket in the center/top panel of the door. Undo this arm from the door and set aside to reinstall later.
4. Manually lift the door about 4” off the ground. Set the two pieces of wood under each corner and lower the door onto the two blocks of wood. If the door is off level, you will see that one side rests on the wood while the other does not. Note again the amount of height that the side that needs to be adjusted should move. For example, if the right side is about 1” above the wood while the left side rests on the block, then the right side needs to come down 1”, or the left side needs to come up 1”.
5. Lock two of your pliers onto the tracks, about 2” above a roller on either side of the door.
6. Now that you know what side needs to move, you need to set your ladder up so you can access the springs. Also, note where the cable falls off the drum as it travels downward to the bottom brackets of the door. The standard scenario is when the cable falls of the back of the drum, close to the wall. The opposite is a non-standard scenario and if that is the case, the springs might be reversed. Either way, set up your ladder and ensure you’re wearing your PPE.
7. Carefully place one winding bar into the cone of the winding end of the torsion spring. Without undoing anything, note what happens when you move the bar up and down, the door will lift and fall, corresponding to you turning that winding cone. You will feel the torsion power lift the door as it should be relatively easy, even though the door weighs possibly over 200 pounds or more.

Notice that if the door were heavier, the winding bar would be pulled downward. Now, raise the bar enough so the door rests on the wood on both sides AND so that you can insert the next winding bar into the next hole on the winding cone.

8. Carefully lower the second winding bar against the door that is now resting on the wood blocks. Both cables should be slightly loose. The winding bar is now holding the tension of the springs by pressing against the door.
9. Leave the winding bar in place and lock your third pliers onto the shaft and ensure the pliers are also hanging off the bottom of the shaft, but firmly against the wall. This way, should your winding bar come out by accident, the shaft is locked into place with the locking pliers which should prevent an accident. But we don’t want the bar to come out in the first place, this is merely a safety precaution.
10. Go to the side of the door you need to raise. Position your ladder so you can access the drum. Carefully undo the drum set screws to the shaft and rotate the drum, tightening the cable by the amount that you need to lift the door. For example, if the door needs to raise an inch, you need to move the drum so 1” more cable wraps on it. 

TIP: Mark the drum and shaft first with a piece of white chalk. That way you have a mark for where the drum’s original position was to use as a reference.

11. Once you have adjusted the drum position, tighten the set screws back up on the drum and shaft. Be careful, you’ll need to tighten them well, but not enough to crack your drum (usually a cast aluminum with steel set screws that can break it).
12. Reposition yourself and ladder by the spring again. Firmly holding the winding bar, undo the locking pliers with the other hand and discard (I wear a tool belt to hold stuff when I do this sort of work). Again lifting and lowering the winding bar, note if the door is now level on the blocks or if more drum adjustment is needed. Follow the procedure again if readjustment is required.
13. Once level is achieved, put tension back on the cables via your winding bars the reverse way you removed a hole of tension (hole being the holes on the winding cone). With the cables now taught, you can double check that the door ended up level.
14. Remove the wood blocks and locking pliers after you’ve removed the winding bars. Test the door manually, for several cycles, before installing operator J-arm. That way, if anything is hanging up, or needs adjustment, you can fix it before wrecking your opener. The door needs to run balanced and smooth for your operator to work best and not burn out.
15. Once everything is smooth and balanced, reinstall your J-arm and reset limits on the operator if necessary, as per the manufacturer’s manual for that model of opener.

While you’re at it, you may also want to check your garage door for dents that you haven’t noticed before. Even a minor bending in your garage door can cause it to constantly need fixing or eventually become wholly stuck in one position if not addressed immediately. Here’s an article I wrote on how to fix a bent garage door.

So, that’s it! Remember that this is a dangerous job, but not that hard if you follow the proper safety precautions. Good Luck!