Just as there are many types of doors, there are even more reasons why one will not shut correctly. Alignment issues, mismatched parts and repairs that were not made right are only a few of the things that can go wrong. Following, you will find a list of a variety of ways to solve the age-old problem of a door that will not latch properly. Once you successfully make the repair, care should be taken to keep all moving parts, such as hinges, in good working order by annually adding a few drops of all-purpose oil or lube.
Beginning to Make Sure The Door Will Latch Properly
The problem of a door not latching is commonly caused by a misaligned strike plate, so the first thing you have to do is to check the strike plate first for alignment. Luckily, this is an easy fix and all that you need is a screwdriver, small chisel, hammer and a pencil or marker. Before you attempt to move the strike plate by completely taking it off and repositioning it, try to slide it into position first.
First, shut the door and take a look at how far off the strike plate is in order for the latch barrel to align with the plate hole. If it only misses by 1/8 inch or less, the problem can likely be solved by tapping the plate in the right direction with a hammer. If this is the case, the misalignment has probably been caused by a very slow shift over time, after becoming slightly loose through normal wear and tear. After tapping the striker plate back into position, be sure to tighten the screws so that it stays in place.
However, if the latch barrel misses the striker plate hole by more than 1/8 inch, it should be removed and repositioned with new screw holes before being tightened into place. The old holes can be filled with a bit of wood filler, which you will find at any hardware store. Once you remove the striker plate by unscrewing either two or four screws, slide the striker plate to its new position and mark the exact position for the new screw holes with a pencil or marker. Next, use a drill to make a shallow pilot hole and, while holding the plate in place, hand screw the first wood screw into place. If your screws are sharply pointed at the end, they are self-tapping wood screws and you may not need to drill pilot holes into the door jamb first.
Fixing A Misaligned Door Jamb
Occasionally, the misalignment of the latch is due to the whole door being off kilter. You may notice that the door swings back and forth when left ajar or that it refuses to stay open by itself. When the door is out of plumb, it requires inserting a little amount of shim between the back of the hinge and the doorjamb, which is usually the bottom hinge. First, loosen the hinge screws most of the way. Next, add a piece of wood shim or other hard material behind the hinge. Then, tighten the screws back up and check to see if the door swings evenly. If not, you might need a bit more shim or to add a small one to the center hinge, which will allow a balancing between the two.
Check That The Door Fits Correctly
Visually check the top, bottom and sides of the door. Does the top edge appear to be level? If it is not, it may cause the door to stick in one corner, or one of the bottom corners may drag along the floor. This calls for sandpaper or a planing tool, which will allow you to shave off a very small layer of wood along the area where it sticks. This will square the door and keep it from binding. Be sure to stop and check at regular intervals rather than filing off too much and winding up with a door that is too small for the frame. Once the door is cut too small, a new door is needed.
Is The Latch Sticking?
If your house is an older one, it may be that the problem is a sticky latch, which is one of the easiest latch problems to fix. Hold the door open and examine the latch barrel's movement as you turn the doorknob both ways. When you have it extended, give it a pull and see if it will come out further. If so, your latch barrel needs a bit of lubrication. Machine oil is available in a spray or a small can with a dropper to make adding just a few drops a breeze. In a pinch, cooking spray or a few drops of vegetable oil or shortening can fix the problem as well. After lubing the latch barrel, turn the doorknob back and forth several times to give the oil a chance to spread along the entire barrel, which will give it back its original range of motion.
If the latch in question is a door lock that refuses to turn easily, try adding a few drops of graphite powder inside the keyhole of the lock. Next, stick the key in the hole and turn it back and forth a few times. This will distribute the graphite and resolve the sticky lock.
If all else fails and you have already inspected the hinges, how the latch and striker plate fit and looked to see if the door is square, you may need a new door. Consider that a hollow-core door is prone to warping as me goes by, because a house settles and puts pressure on the door in uneven amounts. Once a door has warped, it is next to impossible to fix. Installing a new door and new frame is a sure-fire way to get a perfect fit and one that is secure from doors that refuse to stay open or shut. Many DIYers prefer to tear out and install a new frame instead of hanging a new door in an old frame. Alternately, a professional contractor can install a new door quickly and easily and are worth considering if you want to make sure that the job is done right the first time.