In Part 1 of this article, we reviewed the details of casing joinery and how to measure for new casing around a door frame. We also reviewed the necessary cut list, so that you can cut your casing right the first time. In Part 2, we moved on to the details of baseboard. We covered the best methods for installing casing and the use of hand-driven nails in Part 3. We’ll finish Chapter 2 by exploring methods for pre-assembly.
Chapter 2: Part 4
A serial publication of excerpts from Trim Made Simple by Gary Katz
Training techniques for apprentice carpenters and serious DIYers
New adhesives, spring clamps, and fastening systems have made it easier than ever to pre-assemble casing. For casing wider than 3 in., pre-assembly and miter reinforcement—with biscuits, splines, or pocket screws—is the best way to ensure long-lasting miters. To improve craftsmanship—and make the job easier and more enjoyable, use some of the same techniques to guarantee tight-fitting miters around your doors.
|1. Clamp the head to each jig. Use A-clamps to secure an assembly jig to each end of the head casing. Make sure the casing is tight against the stops.|
|2. Glue the miters. Spread a thin layer of carpenter’s glue on each miter.|
|3. Clamp the legs to the jigs. Rest the head casing and assembly jigs on the edge of a sawhorse or on your miter saw stand. Tilt the head casing and each leg into position, squeezing the miters tightly closed. Use A-clamps to secure the legs.|
4. Spring clamp the miters. Glue joints won’t be strong unless they dry under pressure, and putting glue under pressure helps it ‘set’ faster. Use the wrench to spread each spring clamp as wide as possible. Position the clamps on top of each miter (see below).
|5. Carry the frame to the wall. Strong A-clamps make it possible to move the casing off your work area and store it temporarily against a wall while the glue ‘sets’. Wait ten or fifteen minutes before installing the frame.|
Making pre-assembly jigs
On some jobs, I don’t have room—or enough time, to set up a full-size worktable. These simple homemade jigs make it easy to pre-assemble casing without a worktable, using only a miter saw stand or a sawhorse. You should have at least four of these jigs, so several sets of casing can be assembled at one time.
1. Square of 1/2-in. or 3/8-in. plywood. Cut the plywood to about 8 in. square.
2. 1/4-in. strips on two corners. If you don’t have a table saw, a length of 1/2 in. doorstop will provide all the strips you need. Glue the strips, clamp them to the jig, and then tack them in place with brads or pins.
3. Non-slip material. Cut pieces from a router mat (www.rockler.com: $8.79) and fasten them on the back of each jig. Use fast acting glue, like 2P-10 (we’ll cover this in a future article) or contact cement to secure the non-slip material to the jig.
Stay tuned for the next chapter from Trim Made Simple: Casing Windows!
Can you give me any ideas on how to install doors without using any door trim on the sheet rock walls? Using only 3/4″ door frame seems to be the way that some new modern homes prefer to have their doors hung–where can I get specs on how they do this?
For ‘trimless’ or milcore or bullnose drywall, the door jambs need to be kerfed so that corner bead-type metal can be inserted into the jamb. We like to use 5/4 jamb stock for no-mold jambs so that there’s more wood behind the kerf. That means a wider rough opening.
Put some waxed paper under your molding or you will glue it to the jig.
You could also just wax the jig itself with some paste wax.
I mark my door frame as per the article, but then I hold each “leg” up to the jamb and transfer the marks to the casing. Same for the head piece.
I then cut on the marks, then I use a P 2-10 variant to assemble the casings. I give it about three minutes and then carefully carry the whole thing to the door frame and nail it home.
I wish I could just measure one and do all the rest of the casings to that measurement! but I’ve found that in many older homes the elevation difference between the left and right legs makes the assembly line method un-usable. More significantly the differences between different doorways is the culprit, sometimes due to differing floor coverings. Mostly it’s just either the house is “racked” or the original installer was…. quick?
I am surprised that you use a 15 gauge in places, I generally get by with an 18 gauge. Why so heavy?
I did a job last week, stain grade 2 1/4″ flat fir for casings, I used headless 2″ 21 gauge pins and glue. First time I’ve glued casing! but I didn’t think the 21 gauge pins were strong enough over the long haul, and I didn’t want the “nail holes” to show.
I love these aritcles! they make you think :D
On remodels or new homes where we’re installing the casing on top of finished floors (this article demonstrates installing casing on top of rough floor sheathing) and older homes, where things have settled, I still measure and cut the miters before scattering the molding to the openings. But I cut all the pieces a little long and carry a cordless saw with me. I install the head casing first, then turn the legs upside down and mark a pencil line on the butt end, flush with the top of the head casing, then using my cordless saw to trim the butt end. The casing always fits nice and snug to the floor–no measuring. I’ve learned that I can move a lot faster when I don’t pull out a tape measure.
Yes, a 16ga nail is sufficient for most casing, but a 15ga is necessary for thicker moldings. I try to keep things simple and use a minimal number of guns. I don’t own a 16ga gun: 15ga, 18ga, and 23ga. I’ve never attempted to fasten casing to the wall with 23ga pins, only to the jamb, and even then, they don’t have the holding power to keep the casing tight to the jamb, which is probably why you’re gluing the casing to the jamb, too, which is something else I’ve never done.
edit: by glueing I meant that I used the p 2-10 on the miters, and a moulding glue to glue the casing to the jamb/wall.
I love 2P 10, it’s a great cyanoacrylate glue, but like most glues of that type, it lays on the surface and doesn’t penetrate the pores of the end grain. Several times I’ve has miters crack open and break on the glue. I use Titebond II for most interior woodwork because it won’t do that if it’s applied correctly (with clamps and good pressure). If a joint breaks, wood breaks because the glue penetrates the wood fibers. Also, 2P 10 is much more expensive and you can’t use it to seal all the endgrain of a miter like you can yellow glue. I save my 2P 10 for self-returns, non-structural glue-joints, dutchmen, repairs, etc. It’s great for all those situations.
I am a volunteer with Habitat For Humanity and find so many of Gary’s articles helpful in learning construction techniques. I believe these would be beneficial to the other volunteers as well. Is there a complete collection of Gary’s instructions that could be obtained for our local Habitat Office so that all volunteers could read the articles as we move through our builds? Thank you and keep up the great work.
These articles are excerpts from one of Gary’s books. I believe it’s called “Trim Made Simple.”
I can also heartily recommend both his doorhanger’s book and his finish carpentry book (written more for professional carpenters.)
Thanks for another great series, Gary. Will you do an article on jack mitered casing any time in the near future?
I’m hoping SOMEONE ELSE will write that article!
Thanks for all the articles. No matter how simple or complex they are, there is always something to learn and improve. One thing I have never heard many people doing is spreading a super thin coat of glue on each end grain surface prior to putting the glue on and clamping it which increases joint strength by a whopping 70%. I learned it from Marc Adams in Indiana and him from Titebond.
I put a very small amount (just enough to coat the whole piece) of glue on each end grain and rub it in until it it is virtually gone. Let that super thin coat dry to the touch then put another thin coat on each surface and clamp it like normally.
I have pre-assembled 3/4″ pine inside corner trim for newel post trim skirts just using a rub joint method with the above pre-glueing and without clamps. I could hardly break the joints the next morning. I use the pre-glue method on all end grain joints and mostly use a rub joint and they are incredibly strong. The pre-glue covers the “holes” in the end grain and keeps the bonding coat from being sucked up by capillary action. Therefore the glue has 2 flat surfaces to hold to instead of porous end grain. This method has its applications of course but it sure has helped me since I learned it.
I’ve been pre-gluing most miters for several years–almost out of ‘reaction’ to the speed with which the wood (and the mdf) we use these days sucks up with the glue. And it works. Steve Phipps was a big proponent of pre-gluing and there’s no doubt in my mind but that it works and helps produce stronger joints.
Great article as always! I like to make secure the two wobbly side casing legs together (staple) from the back with thin pieces (1/4″ thick) of 3/4″ stock that I saved from ripped down stock. This helps the spring clamps, and the A-clamps to remain still as the glue dries and prevents butterfingers from bumping the loose legs when they are moved around for temp storage.
Parts 1 through 4 really simplified the casing procedure for me . Thank you. Who manufactures the spring clamps for the mitered joints?
CollinsTool.com Same fellow that makes the Collins Coping Foot, and the Bunny Planes, and…
Have you ever used Hartford clamps before? In my experience, they are the best way to clamp casing miters together. They are on the pricey side, but the nice thing about them is they can even hold clamping pressure while the casing is installed.
Nevermind. I actually came across some articles in a recent search where you talked about the Hartford and the new to me Clam clamp.
Gary, your lessons are always valuable for us Carpenters and Remodelers. I appreciate exchanging of work methods and the expert insight of my fellow professional tradesmen. When I do mitered casings I precut a couple pairs of 45° pieces and glue them together with 2p10. I use them to mark the reveal with my utility knife. Using this method shows me ahead of time if the wall is too far out of plane and will leave an unsightly gap between the casing. When the wall is backed out of plane with the jambs I use another method to correct this. I cut the same setup of two scrap pieces at a 45° angle and a slight bevel (compound cut). I use a compound saw but, you do not need a compound saw to do this. Lay a thin shim or your pencil under the leading edge of the cut end and make the cut. Different thicknesses of the shim will give a variety of bevels without adjusting the compound bevel on the miter saw. I glue them together and check the fit to the wall. This allows the outer edge of the casing to lay flat against walls out of plane and no caulking to fill gaps. I use good judgment and do not install casing where the bevel makes the casing look obviously tipped. In that case I would rework the jamb or wall as needed. When gluing up I wipe trim glue on the edge towards the surface and 2p10 at the back edge of the miter. this seals the grain surface edge and gives instant gluing.