My Unique Situation
The basement floor has a very dramatic slope towards the floor drain. Leveling the slab, by applying a skim coat of concrete, was not an option, because of head room issues. And removing the slab, and digging down a couple more inches and pouring a new one was simply cost-prohibitive (no, I did not get any estimates– hiring out any portion of the basement renovation would have cost prohibitive). So I was stuck with a sloping floor, and I had to take it into consideration for many aspects of the basement project. The new doors not only had to be trimmed because of the lower ceilings, but the bottoms of two of the doors had to be trimmed on an angle so that, when closed, the bottoms would be parallel with the floor.
Cutting doors to size.
It is very easy to confuse measurements when trimming doors, and that confusion is compounded when a sloping floor is involved. What we did wrong was try to work with the big numbers– the height of the door and the height of the door frame– rather than the small numbers– the amount to cut from each piece. By the time we figured out this not-so-magic formula, we had hung the last door.
The not-so-magic formula (which should have been obvious):
Measure the rough opening. In the case of having to accommodate a slope, you will have two measurements: one for each side. Remember which is “left” and which is “right” and account for the direction of the door swing.
Subtract your measurement from the manufacturer’s required rough opening. This is the amount to trim from the frame and the bottom of the door. Quite simply, if the opening is 2 inches shorter than required, the door and frame should be trimmed by 2 inches.
Where a slope is involved, mark the “left” and “right” measurements on the door (DON’T mix ‘em up like I did) and connect the dots, so to speak. Now it’s just a matter of cutting along the line (use a straight edge)
The manufacturer recommends trimming no more than 1/8 inch from the top or bottom of the door. I had to trim considerably more. In each case, the cut was as wide or a little wider than the bottom frame of the hollow core door, so I was able to reuse that piece. After cutting, I removed the door skin material from the frame piece, applied wood glue to all contact edges, and tapped it back into place with a rubber mallet. I then clamped it and allowed the glue to cure.
The instructions make it sound so simple. Fit the frame in the rough opening and install shims to keep everything nice and square, plumb and level. Yep, sounds simple enough. If only it were so! The frame may look good to the naked eye, but the slightest bow or rack can prevent the door from swinging or closing properly. After a lot of trial and error, (there’s that phrase again) along with equal parts of head scratching and hair pulling, with an occasional expletive yelled at no one in particular thrown in for good measure, we unceremoniously ripped up the instruction sheet and threw it in the recycle bin.
How We Did It: With the door frame pre-assembled as per the instructions, we placed it in the rough opening. We first leveled the top of the frame and fastened it in place. We then hung the door on the hinges. Starting at the top of the hinge side, we installed a pair of shims. Before installing screws, we checked the swing of the door. Then we moved down and installed the next pair of shims. Each time we installed shims and screws (about every foot or so) we checked the swing of the door and made sure it closed properly. We repeated the process for the latch side. Having the door in position made it easy to fine-tune the position of the frame with the shims.
The proper way to do it: The key to hanging a door successfully hinges on this: the hinge side needs to be perfectly vertical and plumb– that is straight up and down from side to side and front to back. This can be achieved with the assistance of a level and a plumb bob. The corners of the frame need to be perfect 90 degree angles. This can be achieved using a speed square. That’s the difference between a hack job and a proper installation. But sometimes you can get away with a hack job, like we did, if you are able to eyeball things fairly accurately.