Making Window Trim – My Old House Home Improvement

In order to make the new washroom fully functional, I’ll have to get the ceramic tile installed around the new bathtub. Since the tile will extend up and around the new window that’s above it, the trim needs to be finished before I can start that work.

I’m going with a relatively simple design, but one that I think is appropriate for the age of this house. All of the parts will be made in my shop from plywood, MDF and solid wood to create trim that is good looking and economical. This is one area where doing it yourself can save a lot on money, and you can make it exactly as you want it to be.

Here’s the overall design:

The side casings are in two parts, the flat casing itself and a back band. The casing is made from MDF and features a simple step down near the jamb. The back band is solid wood and lips over the casing to add depth and durability to the edge of the MDF:

The stool is just bullnosed and is solid wood. The apron underneath is a cove molding. Traditionally the apron is made from a piece of casing, but I think that detail looks too “heavy” and I like the cleaner look of the cove better.

The head casing is made up of three pieces:

The cap and head casing are MDF, while the bead molding is made from solid wood.

I made three videos of the process showing how each part is made and installed, starting with the jambs:

Then the side casings:

The head casing and installation:

The jambs for each window are made from 3/4″ paint grade plywood. Using plywood will eliminate any possibility of seasonal expansion and contraction that is a problem with wider pieces of solid wood. It’s also less expensive, stays flat and is very durable.

The windows themselves are vinyl and have a slot to receive a trim piece for a jamb extension. Rather than buy that trim piece to use, I’ve cut a rabbet in the edge of the jamb to create a tongue that fits into the slot. This locks the jamb into the window and has a much cleaner look:

The jamb includes the sill and is preassembled as a four sided box before installing it into the window opening. Some of the tongue on both ends of the side jambs needs to be removed to clear the welded corners on the window:

The assembled jamb is brought in and installed in the window opening. A bead of caulk around the edge where it meets the window helps to seal any gaps and “glue” it in place:

Wooden shims are placed around the jamb and nails are driven through to the framing. The shims are then cut off flush with the face of the wall.

Next, the side casings. I’m using 1/2″ MDF with a simple step down cut into one side with the table saw. The back band is solid wood with a rabbet that fits over the casing:

These are cut to length and installed by nailing them into the edge of the jamb and through to the wall framing. The casing is set back from the edge of the jamb by 3/16″ to create a reveal. This leaves a portion of the plywood edge exposed, but this will be remedied with a bead of caulking.

The stool is 1″ thick and half round on the front. After it has been cut to length, the ends will also be rounded on the disk sander:

The stool is attached to the jamb with biscuits and glue, and extends past the side casings by about 1/2″ on each end.

The three piece head casing comes next, starting with the bead molding:

The casing and cap come next, glued and nailed in place.

Before painting, all of the nail holes are filled with a mixture of sanding dust and drywall joint compound:

The filled holes are left to dry overnight and sanded smooth. As mentioned earlier, the reveal is caulked with latex sealant and this covers the exposed edge of the plywood. Any other gaps are caulked as well and it’s ready for priming and painting.

Although I can’t install it until after the tiles are done, I still made the cove molding for the apron using the table saw and a simple jig:

The rest of the windows in the house will be trimmed in the same way, but that will happen much later. The interior doors will have a similar detail, but not identical.

As you can see, a very attractive overall look can be achieved using simple methods and inexpensive materials. The finish here is paint, but the same design would work with a natural or stained finish, just substitute solid wood for the plywood and MDF parts.

In the next chapter, the ceramic tile will be set and grouted around the tub in the new bathroom.