How to Install Interior Window Trim | Ask This Old House

This Old House general contractor Tom Silva installs interior window trim using hand tools. (See below for a shopping list, tools, and steps.)

Shopping List for Installing Interior Window Trim:
- 1x4 primed pine, used to make window trim
- 120-grit sandpaper, for smoothing the window stool
- 2-inch (6d) and 2 1/2-inch (8d) finishing nails
- Carpenter's glue
- Damp cloth, used to wipe away excess glue and sanding dust
- Wood putty, for filling nail holes
- Interior-grade paint

Tools List for Installing Interior Window Trim:
- Layout square, used to mark square cutlines
- Handsaw, for cutting the wood trim
- Block plane, for rounding over and smoothing the window stool
- Hammer
- Scriber, used to mark the stool notches
- Nailset, for setting nailheads
- Putty knife, used to apply wood putty
- Sash brush, for painting the trim
 
[BOLD "Steps for Installing Interior Window Trim:
1. Mark the location of each side casing on the wall.[BR]
2. Measure and crosscut the window stool to length from 1x4 primed pine.[BR]
3. Rip the window stool to width using a handsaw.[BR]
4. Use a pencil scriber to mark a notch on each end of the stool.[BR]
5. Saw the notches from the stool so it fits snugly around the window stops.[BR]
6. Round over the sharp edges and ends of the window stool using the block plane and 120-grit sandpaper.[BR]
7. Fasten the stool to the window with 2[FRACTION 12]-inch finishing nails.[BR]
8. Tap the nailheads below the surface using a hammer and nailset.[BR]
9. Saw the side casings to length, then glue and nail them in place with 2-inch and 2[FRACTION 12]-inch finishing nails.[BR]
10. Nail up through the underside of the window stool and into the bottom end of the side casings.[BR]
11. Mark and crosscut the head casing to length.[BR]
12. Glue and nail the head casing across the top of the window.[BR]
13. Mark and cut the apron to length.[BR]
14. Apply glue along the top edge of the apron, then nail it to the wall directly below the window stool.[BR]
15. Wipe away any excess glue with a damp cloth.[BR]
16. Fill all nail holes with wood putty. Once the putty dries, sand the surface smooth.[BR]
17. Wipe away sanding dust with a damp cloth, then paint the trim.

About Ask This Old House TV:
Homeowners have a virtual truckload of questions for us on smaller projects, and we're ready to answer. Ask This Old House solves the steady stream of home improvement problems faced by our viewers—and we make house calls! Ask This Old House features some familiar faces from This Old House, including Kevin O'Connor, general contractor Tom Silva, plumbing and heating expert Richard Trethewey, and landscape contractor Roger Cook.

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How to Install Interior Window Trim | Ask This Old House

[Ariztid]

It's amazing how clear this footage is from the 1930s.

[keithrayeski]

What a treat to watch a master carpenter doing things the good ole fashion way....with manual hand tools!!! It's what sets them apart!!

[fixitwithzim]

That rip cut on the stool with a hand saw...Imagine trimming a whole house that way? Makes you appreciate power tools and the guys back in the day that made a living working with hand tools.

[isaacweymouth]

Tom's freehand straight line is most impressive, and is a technique that transcends trades that everyone should practice. He is locking his middle finger in place against his thumb, and using it as a stop to drag against the material. You also see him use this technique when drawing the wood glue down the boards, and could be used for, say, silicone in a bathroom, or cleaning caulk lines.

[elephantmonkey]

Wow, this looks so easy. I can't wait to try it, spend several days trying to replicate and then hire a contractor to correct my work.

[richardcesarano]

Awesome carpenter. I worked years back with a gentleman like Tommy. Old timer, only believed in hand tools. Gotta respect a true tradesman...

[akeene]

I promised to install a window, jam, and trim. I promised the homeowner this knowing I dont know the first thing when it comes to trim. I have watched this three times, and now i'm confident I can do this project tomorrow! wish me luck

[Psychlist]

"Tommy, I'm pretty impressed with all that."

*crickets* :)

[veronabriscoe]

Amazing to watch a skilled craftsman. My teacher was like this. I can tell from some comments, that there are some who are not so skilled and or haven’t been taught what to do, when you don't have your power tools or modern gadgets!!

[MrEazyE]

We're all impressed with Tommy, lady.

[kylepost]

No one:

Tommy: *freehands a straight line*

[williamskrainski]

Tommy's going to go out in the yard and forge the nails

[tlew]

I wish I had a mentor like Tommy. What a great dude.

[samuelgarza]

That's the way my father does it !i do a least 3 windows by time he installs 1!!! I'm very grateful for power tools!!! Pops does it old school...good video .

[realgreycreative]

One of the most impressive things I've ever seen Tommy do ... Very nice

[bruce-le-smith]

I like Tommy's chuckle about the math help, seemed genuine/personal

[tmq]

I love watching Tom Silva. This guy is the absolute pro at anything wood.

[MoPoppins]

I always love Tommy's lifehacks for measuring things. He makes it not only less-intimidating, but actually FUN to take on the challenge of accurately measuring things without worrying about the numbers. Tommy's got a great brain for seeing the interconnectedness of things, which is awesome since most American math education doesn't teach us about number relationships.

[noahgondo]

“I wanna get it stawted on my saw hawse”
East coast accents are truly the best. Very skilled guy, can tell he’s been doing that awhile.

[davidhinson]

The only man I know that can drive a trim nail with Paul Bunyan’s hammer!