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Installing a Pre-hung Door

Presented by Infinity Construction Group

Infinity Construction provides high quality home renovations in Maple Ridge BC, and throughout the greater Vancouver area. Custom door installs are a specialty.

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This is a guide for the everyday homeowner who would like a little overview of the steps involved in installing their own exterior pre-hung door. I will assume you have chosen a particular style of door from your local supplier and would like to go about ordering it.

Measurements for ordering If you own an older home circa 1950 you will most likely need to order a custom cut prehung. The best way to get the proper measurement is to remove both the inside casing and the exterior molding. Whether your home has plaster walls, drywall or just about any other finish you should be able to see the outer edge of the door jamb. Take your tape measure and measure it from side to side. The next measurement is the height. This will need some common judgment on your part. New door installed

Older homes may have a large 2 ½” thick threshold, (bottom part that you step on), and it may be sitting right on the floor joists or some type of plywood or boards. You should also

make note if the threshold is butt up to existing flooring like tile or hardwood. Most new style door thresholds are aluminum and are only 1 ¼” thick so you may have to build up under the new door frame so it will open up over top your flooring and perhaps that throw rug you have in front of the door. Take the tape and hook it on the top of the door jamb and measure down to the existing floor then add 1”. This measurement will allow you about ½” of play when opening the door. The final measurement is the depth of the frame. Hook the tape on the inside of the jamb which should be even with the inside wall and measure to the outer edge of the jamb. These measurements are the outside frame measurement, OFM, and are essential to have when ordering a prehung door. The next step is determining the swing of the door. If you stand outside your home and face the door you can figure out the swing. If you reach for the handle and open the door and it swings in to the right, it’s a right handed door. If it swings to the left, it’s a left handed door. Don’t forget the little details like having them drill holes for the handle and dead bolt. You should choose the hardware and have the specifications ready to give them since the distance apart and the distance from the edge of the door edge will vary. A peephole is often required and should be drilled for the shortest person that will use the door. Sometimes a mail slot is required as well. A security door wrap and large heavy-duty strike plate may also be ordered and notched out in the frame at this time. With the above information in hand you can go and order your door system and ask the sales person any other questions you may have. When you go to pick it up you will need some installation accessories from the store as well.

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Installing the door I will assume you have the basic tools to do the job and mention them as I go through the installation process. Be sure to pick up a bundle of pre-packaged door shims. If you have some wood scraps at home utilize them too. A small box of 3” #8 wood screws and a mini bundle of insulation or some (low or no expansion) spray foam. You’ll also require new brick molding and new inside casing. In some instance you may want to reuse the trims so that they match others in the house, save them. If it is not crucial I suggest you install your door then go and purchase the appropriate sized trims to finish the job. The average door takes 4-6 hours to install if you have all the tools and material ready. Don’t worry if it takes longer. Even if you only get the pre-hung installed in one day and finish the trim the next day you're doing good. So, you picked you picked up the pre-hung and accessories and are at home ready to go to it. The first thing you should do is remeasure the old door and then double check the new door. I’ve had some doors torn out and been ready for the new one only to find out the measurements are wrong. Before you start have a broom and dust pan on hand and a garbage bag or can close by. ALWAYS clean, clean, clean as you go. It’s nice to put a throw tarp down inside as well to catch debris and help save the flooring. Be careful if there is tile or hardwood and you use a throw tarp – it’s slippery. Assuming nothing is to be saved remove the door slab by popping out the hinge pins and move it out of your way. Next take the saw of your choice, (reciprocating saw, circular saw, hand saw, chain saw), and cut both sides of the frame about half way down in a horizontal motion. Be careful of alarm and doorbell wires. Use a crow bar to pry the sides away from the wall. Normally there are 3 or 4 nails on each side and none on top or bottom. Pull the frame away from the walls and DO NOT pry against the inside or outside finishes or they will be damaged. Be sure to save the alarm and doorbell wire for the new frame. Take time to sweep and vacuum the area and move the old frame out of the way.

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Take your level and check the bottom for level. Also check the flooring thickness at this time and build up the bottom so the door will sweep over the existing flooring. It’s crucial the bottom is level. Find the center of the opening and mark it using some tape placed on the floor inside. Then find the center of the new door frame and mark it with some tape. This needs to be done so the trims, mainly on the outside will be evenly spaced on the outside opening and the moldings will fit in and look proportionate. Take your new door slab out of the frame. It’s easier at this point to work with just the frame. Lean it near the door opening. Keep your drill, level and shims at arms reach. •

Remove the weather stripping from the door frame if it is the push in style. The screws will be hidden under this weather strip area. You can also place the screws right into the jamb anywhere you think easiest and fill the holes later.

Make sure the floor is level. You can add a shim at this point and tack it in with a small finishing nail so it doesn’t move around.

Place your frame in the opening at center. Check to see that there will be room for the door to swing over the flooring. You can screw a piece of wood directly to the bottom of the door frame at this point. Shimming is ok as well but it won’t offer full support and you may get movement when you step on the threshold.

Place a shim on both sides of your frame right at the bottom so it won’t move side to side.

Check to see if the frame will sit flush with the inside wall or at least 1/8” in or out. If the existing flooring is stopping the frame from moving in all the way you have 2 choices. Cut the problem off the floor or dado, (notch out), the frame so it will sit over top the obstruction.

Fasten the frame at the shims on the hinge side of the frame. Take your level and level in to out and side-to-side and place a shim as required under the top most hinge. Use a screw and place it just under the shim, (you may move it later for fine tuning).

Hang the door on the hinges and see how it looks. Remember level the door as best you can – DO NOT line it up with the framing itself. If it swings easily and doesn’t shut or open by itself, your almost there.

Take another shim and pack it about 6” from the top of the latching side. Close your door gently and line up the door evenly with the latch side. Secure it with a screw.

Visually check the gaps around the door and pack 3 shims on each side. Usually pack the shims under each hinge and be sure to pack some just under the deadbolt hole.

Put the hardware on at his time and confirm it works and the lines are still looking good. It is typical you see a thin sliver of light at each bottom corner of the door. The door supplier will most likely have supplied you with 2 fuzzy dust strips that simply stick on the jamb at these 2 points.

Reset your alarm at this point and doorbell. Put your insulation in. Do not over pack or spray it or the jamb will rub the door after.

The trim is ready to go on. I start by putting the inside on first. If the finished wall is protruding take a utility knife and carve it down. Pin your trim every 12” on the frame and the wall. The exterior trim is usually the more difficult one to do. You can assess what type of trim is required at this point. I normally use a 2 ¼” x 1 ½” brick moulding. You may find the exterior finish doesn’t quite line up equally even though the bottom is centered, that’s ok. You can choose to cut the exterior to be even or manipulate the trim. Generally the standard is to measure ½” back for a reveal, this allows for a screen door to fit on later down the road.

Get that table saw out and dado the trim so it fits over top the exterior finish then pin it on. Use polypropylene to seal it to the exterior and a good wood filler to get the nail holes in and out.

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Hopefully this article has helped you install the door with little or no surprises. The same procedure is used for interior doors as well. Double, triple and quadruple doors are a whole other ball game and another article.

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