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Simple, Easy Instruction for Casing Interior Doors

Casing interior doors is the final step to applying trim to your doors and gives the finished look to your doors. There are different styles and sizes of interior door casing available. Also different methods to apply these styles but I will be explaining the most common and popular styles for the purpose of this page keeping things simple for the people applying these methods.

Lets get started by assuming that the door is already hung and nailed in the opening properly and that you are set up with all the tools and materials necessary for this job of casing interior doors. To achieve a nice professional look as I have said before it is a good practice to match the wood grains and colors of the casing for each door.

Start At The Top Of The Door

While casing interior doors there are a few problems you may run into and I will do my best to explain these as we go. The first part of the interior door casing you will start with is applying the top piece.

  • Grab yourself a piece of casing and lay it finished side down with the thickest part of the casing toward the saw fence and the thin part towards you.

  • Move your miter saw to the 45 degree angle towards the long part of the wood and carefully make a 45 degree cut on the end of this piece.

  • The reason that you cut this casing upside down is because this gives your cut a natural and slight bevel back at the cut. In other words the finished side will be slightly longer so the two 45 degree cuts will be tighter at the miter where the two cuts meet.

    Cutting Long For The Reveal

  • Now the easiest way to explain this is to go to your door and measure from inside corner to inside corner at the very top of the jamb then add about a quarter inch to your measurement for the reveal. The reveal is the area of the jamb that is left exposed after the trim is applied. The reveal is normally about one-eighth to three sixteens of an inch wide all the way around the door. This measurement for the reveal is pretty standard and can be applied when you are trimming just about anything.

  • Back at the saw transfer your measurement to the casing at the thin part of the casing. The thin part of the casing will always be the shortest part of the casing with the thick part being the longest after the two ends have the 45 degree cuts.

  • Move your saw to the 45 degree angle and again cut this piece upside down so you get the bevel for a nice tight miter. One thing I always do is cut as close to my line without cutting the mark off. Refer to tips tricks difficulties and techniques of casing interior doors link farther on in this page for extra help.

  • Applying Casing With Speed And Quality

  • Now if you have been following my page you will aready know that being in business as a trimmer speed as well as quality are big issues with me. So when I am casing doors or windows for that matter I hardly ever use my tape measure.

  • What I do is cut a 45 degree on one end, Take my piece to the door hold it in place exactly where I want it mark it then back to the saw to cut it. Now if you have more than one door this size then you could cut all your top pieces for this size door at one time.

  • Ok you should be ready to apply the top piece at this point of casing interior doors.

  • Hold your casing in place at the top of the door exactly where you want it keeping the reveal the same and equal also you can eye this.

  • In your other hand you should have your little finish gun which shoots 18 gauge nails. Shoot a nail in about an inch or so in from one side and about a quarter of an inch up from the thin part of the trim.

  • Shoot another nail in on the opposite side same place and way. That should hold it now in place, the idea is just to tack it here for now.

  • Now we are ready for the side pieces of casing and you will not need to measure here. Simply grab yourself two pieces that are long enough and head back to the door.

  • Just take one piece and hold it in place where it is to be nailed. Be sure your casing is long enough and is resting on the floor, that way you have a little adjustment if your miter does not fit tight and is not satisfactory for your tolerance.

  • Put a pencil mark at the point where the top piece intersects the side piece. Repeat for the other side. Now back to the miter saw and cut these two pieces in the same manner as described above.

  • Your pieces are cut now and ready to be nailed and installed. Nailing these pieces of casing on does take a little technique and patience. As said before there are some problems and difficulties you may run into here, so refer to this link finish carpentry tips for extra help.

  • Proper Nailing With Your 18 Gauge

    Ok we are on the home stretch of finishing casing interior doors.

  • First thing is to apply some ordinary carpenters glue to the 45 degree cut.

  • Set the casing in place and apply pressure upwards into the top piece causing the miter to close up tightly. When the miter is tight to your satisfaction shoot a nail in about an inch down from the inside corner of the miter and again about a quarter inch in from the inside of the casing.

  • About four inches down shoot in another nail again you should be using your 18 gauge finish nail gun.

  • Now go back to the top and at the top corner of the casing, looking down shoot a nail vertically down at the corner so it penetrates through the miter drawing and nailing the miter together. Be very careful doing this being sure your gun is held straight up and down so the nail does not glance off or pops out into the finished part.

  • Now go ahead using your little finish gun shoot the casing on all the way to the floor spacing the nails about 6-8 inches apart at the inside or thin part of the casing. Repeat procedure for the opposite side.

  • Working With Your Miters

    After you have the side pieces nailed with the little gun you move on to the the top piece to finish nailing. You still may need to work your miters a little and can do this by slightly pulling down in the center of the top piece and maybe pulling the top outward. This shifting of the top piece should be just slight and nailed across while held in place again with the little gun and only at the thin or inside part of the casing.

    To finish nailing we will need the big finish gun. My choice for this is a 16 gauge with two and half inch nails. You will be shooting the casing at the outside or thick part only with this gun.

  • Start on either side shooting a nail in about 6 to 8 inches down from the very top of the casing so as not to mess up your mitered corner and then moving down shoot in maybe 4 to 5 nails spaced accordingly.

  • Repeat for the opposite side.

  • Now for the top piece I like to take my flat tool and stick it behind the casing at the top outside corner and applying slight pressure outward and at the same time shooting a nail in about 4 inches in from the corner next to your flat tool thus keeping the miter tight so the power of the gun doesn't draw your miter apart from the force of the shot.

  • Repeat for the other side and maybe 1 or 2 nails towards the inside.

  • This concludes casing interior doors and your door should be finished, look professional and you should be happy and confident for the next door. This will get easier as you go. Refer to the tips tricks difficulties and techniques of casing interior doors finish carpentry tips for help.

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