How To Trim Exterior Windows

Synopsis: Trimming exterior windows can be an ordeal, unless you larn the lessons that Seattle builder Mike Vacirca presents in this article. Vacirca's process for exterior windows begins by assembling the trim first, and then installing it as one piece. He starts by measuring every window to be sure he has correct dimensions. Vacirca then mills the windowsills, and is sure to continue the casing square during associates. Finally, he installs the unit of measurement, nailing in the casing simply screwing in the sill.

I can no longer phone call myself a trim carpenter because these days, I practise a little flake of everything. I was a trim carpenter for most of the by 15 years, though, and a boat builder before that, so I experience comfortable saying that I know a thing or two nigh trimming out a window, and about how water affects wood.

Every fourth dimension I dropped a piece of window trim from scaffolding 30 ft. in the air, I found myself remembering another career past, the days I spent working in a cabinet shop, where work is easy to command and atmospheric condition isn't a business organisation. Finally, I came to my senses when I was presented with 27 windows to trim for ane house. That chore helped me to develop a method for installing exterior trim that's easier on my trunk, that is safer and faster, and that also yields more than durable results. To make this procedure equally efficient as possible, I even prime, putty, and pigment the casings before installation.

Cutlists and stations add efficiency

When I worked in the chiffonier shop, I organized my projects with cutlists and made shop drawings that showed how everything was going to be built before a saw ever touched wood. The process I created for assembling window trim in the shop starts with that premise. As with the cabinet work, I organize the store into efficient workstations to build the trim. I want the workflow to move so that the pieces are cutting and the assembly happens in such a way that a few folks can work at the same time and not get in each other'south way. The procedure, however, begins on site.

When the windows go far, I grab a tape measure, get a notebook, and make a list of all the windows. I measure each to make up one's mind the finished top and width so that I can make a cutlist. I add ane⁄8 in. to each dimension to allow for caulk and to be sure the casing units volition install easily by merely slipping over the windows. Finally, I intermission everything into a formula. To continue rail of which window is which, I use the lettered labels attached to them at the manufacturing plant. Once the casing unit of measurement is congenital, I mark the respective letter on its back.

I install painted trim, then I build everything with primed stock. I cut all the pieces get-go, then assemble each unit with biscuits, glue, and screws to ensure that joints won't open over time. In one case all the units are built, and the smash and screw holes are filled, I prime number whatever exposed wood and requite everything a first coat of terminate paint.

Get the proportions right

The windows on the project featured here are a mixture of Marvin (www.marvin.com) double hung, casement, and fixed units. All of the windows have aluminium-clad exteriors and primed wood interiors, and they are installed with a nailing flange. The nailing flange is set 1 in. dorsum from the face of the unit, which in turn ends upward one in. proud of the unsided building.

Because i of the functions of the trim is to protect the window, I like to use at least five/four-in. stock. Likewise, if at that place is going to exist a reveal between the ii components in this assembly, I prefer that the trim be proud of the window. Leaving the window proud of the trim looks cheap.

Getting the trim width right can be a fleck trickier. Stock dimensions (3 1⁄two -in. and 5 1⁄two -in. boards) rarely create pleasing propor tions. The correct width typically depends on the size, the shape, and the fashion of the house and windows.

The windows on this house called for a Craftsman-style trim design, which I cre ated using various reveals. By bumping the head casing upward to i 1⁄2 in. thick and by hav ing it extend past the legs by 1⁄2 in. on each side, I was able to practice two things. First, the thicker head casing provided additional protection to the window. Second, the 1⁄4 -in. reveal between the head and legs added a subtle shadowline to create an interesting wait. Both the head and the leg stocks are factory-primed finger-jointed cedar. Information technology'southward sta ble and conditions resistant, and it takes paint well. I eased the edges for a softer look and a more durable terminate.

I milled the sill from durable Douglas fir. The sill's shape is all about function. The top is pitched to shed water, and the lesser is kerfed to prevent water from wicking up behind the trim.

I made the sill run past the casing by one⁄iv in. on each side also. I plugged the head and the sill reveals into my formula, so I was able to cut everything first and gather the pieces later.

I've used this process on four projects at present with 4 dissimilar window-trim styles, and the results have been uniformly crawly. The trim units go upward rapidly and painlessly, and the painter I piece of work with loves making simply one trip to fill up nail and spiral holes and to caulk, and ane trip for a final (second) glaze. I don't have to worry as much nearly the conditions, and my body is thankful for the boosted residue.

Mill the sill

Utilize a stable material like clear vertical- grain Douglas fir (shown here). Shape the stock, add a baste border, then prime with a high-quality exterior primer.

shape the wood with an angle when making trim for exterior windows — **Straight stock gets an angled rip.** Beginning with an advisable length of 21⁄2-in. by 13⁄4-in. stock. Rip a fifteen° bevel to create the sill'due south pitched face. Lower the blade and reset the fence. Then kerf the lesser of the sill to create a drip border.

planing the face of the wood smoothly — **Aeroplane the face smooth.** Use a power planer to remove saw marks and to dimension the sill's flat top to equal the depth of the window's cladding.

Go along the casing square during assembly

Biscuit the legs to the head, and glue and smash the sill to the legs. Use an exterior glue such as Titebond III (www.titebond.com). Dry-fit the pieces before assembly. I bar clamp is enough to hold things together equally the glue dries. Use a framing square to bank check the assembly throughout the process.

slot the legs and head of the wood for the trim — **i Slot the legs and the head.** When the head and legs are different thicknesses, annals the fence to the dorsum of the stock. Register off the face when joining heads and legs of the same thickness.

toenail the corners of the trim for exterior windows — **2 Toenail the corners.** Place a toenail in the inside edge of the leg using 21⁄2-in. galvanized finish nails. This adds strength to the joint while the glue dries so that information technology doesn't twist during the rest of the assembly.

nail the window sill to the legs — **3 Nail the sill to the legs.** Attach the sill to the legs with glue and 21⁄ii-in. galvanized end nails. Leave the unit of measurement clamped for an 60 minutes while the glue sets up. Prime the end grain, then fill nail holes with a solvent-based wood filler similar PL FI:X Solvent Woods Filler (www.stickwithpl.com). Consummate the casing with one or ii coats of end paint.

Nail the casing; screw the sill

The unit slips over the win dow, then is attached to the firm with stop nails and screws. The legs and head are caulked between the casing and the window; afterwards, the head casing is flashed into the housewrap.