The front door was sagging, making it hard to close the door because it would contact the jamb and threshold. The gap is clearly visible in the following photo.
Sagging Front Door
Required Tools
The following tools are required for this project:
- Carpenter’s square
- Carpenter’s level
- Pencil
- Wood chisel – 1 inch wide
- Cordless drill
- Hammer
- Philip’s screw driver
- A helper – preferred for the awkward part of removing the door
Finding the Cause of the Door Sag
To determine why the door was sagging, I checked the following with a carpenter’s square and bubble level:
- The door frame was square and level
- The door was level
- The hinges were securely fastened and not bent
I found that the sag was due to the door frame being slightly out of square, the result of minor setting of the house foundation over the past 8 years. To fix the problem, I could either tear out the entire door frame and rebuild it (this seemed extreme for such a minor problem); or I could reset the middle- and top door hinge mortises and be done in 30 minutes.
Fixing the Sagging Door
To fix the door, it needs to be leveled by cutting the middle- and top mortises about 1/8 inch deeper. This would pull the door to the left and lift the door up.
Begin by removing the hinge pins by driving them out with a hammer and Philips screw driver. I recommend getting a helper here to hold the door in place.
Remove the Hinge Pins
The door hinge leaf and mortise are shown after the door is removed. A mortise is the recessed pocket cut into the door jamb such that the hinge leaf is flush with the wood surface.
Door Hinge Leaf and Mortise
Remove the four screws in the hinge leaf with the cordless drill/driver.
A Note about Wood Chisels
A wood chisel should be razor sharp to make easy and precise cuts. A diamond sharpening stone with a coarse and fine side does a superb job of quickly putting an edge on tools and knives. Diamond stones are more expensive than natural stones, but well worth it in my opinion.
Wood Chisel and Diamond Sharpening Stone
Cutting the Hinge Mortises
Cut the outline of the mortise to the a depth of 1/8 inch (use your judgement – but a little goes a long way!) as shown here. Make the perimeter cuts first for a clean “stop” when shaving out the interior. Notice the flat or bottom side of the chisel is against the outside of the mortise.
Outlining the Mortise
Position the chisel 1/8 inch below the mortise surface and lightly tap the hammer to shave away the wood.
Cutting the Mortise
Continue shaving away the wood across the face of the mortise.
Cutting the Mortise
After removing the bulk of the material with the hammer, shave off any high spots by hand as shown here.
Smoothing the Mortise with a Chisel
I cut the middle hinge mortise 1/8 inch deeper the same way. Recall the bottom hinge is left alone.
To remount door:
- Reinstall the hinge leafs with the four screws.
- Set the door on the hinges and reinstall the hinge pins.
- Check for proper operation.
The door opens and closes effortlessly now. I have to keep reminding the kids it’s not necessary to slam it anymore!
The sag is fixed in the next photo. Notice the door is plumb with the jamb.
Door Fixed - No Sag and Plumb with the Jamb
Door Bottom Weatherstrip
A sagging door can damage the weatherstrip (a.k.a. door sweep) on the door bottom. This posting illustrates how to replace the door bottom weatherstrip.
Hope you find this helpful.
Bob Jackson
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Hello, Useful information for pocket screws and your post regarding Fix a Sagging Door | HandymanHowto.com looks very interesting. I just wanted to say good work on your site, I like the look and the information was useful.
I have had a deadlock strike and sagging door problem for a while.
I finally took a good look and the fix was easy.
The top hinge was lose. The installer forget to put 2 out of the 4 screws on the hinge plate on the frame. No holes present so the screws had not fallen out, just omitted. Like you often say contractor quality!
I tightened the 2 good screws and that fixed the door sag and deadlock problem. I then added 2 screws to complete the contractors work.
It was so quick I even had time to grease the hinges to fix the hinge squeeling noise.
I talked to a pro maintenance guy that door sag is mostly the hinges working lose.