Picture Frame Window Casing — Mitered Trim on All Four Sides
Four pieces, four miters, no ledge. Picture frame casing is the cleanest window trim there is, and the least forgiving, because every corner has to close and stay closed.
Picture frame window casing is the same casing on all four sides of the window, mitered at the corners, with no stool or apron. JMB Builders installs picture frame window trim across the Twin Cities metro: extension jambs where the window needs them, casing set to an even reveal, corners glued and pinned so the miters stay closed, filled and caulked. Priced per window, quoted from photos within one business day.
- Priced per window, jambs included when needed
- Corners glued and pinned so miters stay tight
- Quote from photos in 1 business day
- Licensed MN contractor BC809005
Picture frame casing treats a window like a door: the same casing runs up both sides and across the top, and a fourth piece runs across the bottom instead of a stool and apron. The corners are mitered, the reveal to the jamb is the same all the way around, and the window reads as a simple rectangle on the wall. It is the trim most newer homes have on their doors, so putting it on the windows makes the whole room agree.
The catch is the miters. A window casing miter is a joint between two pieces of wood that will each move a little with every Minnesota season, and a miter that was just nailed opens up at the outside corner by the first winter. A miter that was glued, pinned across the joint and set on a jamb that is flush with the wall stays closed. The second catch is the opening: a picture frame shows any out-of-square immediately, so the jambs have to be true before the casing goes on.
JMB Builders installs picture frame window casing across the Twin Cities metro: on drywall-return windows that need jambs and casing, on replacement windows left bare, on new construction, and on old windows where the stool-and-apron trim is coming off for a cleaner look. Priced per window, matched to the casing on your doors.
What you supply
- A straight-on photo of the window and one of a door casing in the same room, so the profiles match
- What is there now: drywall returns, bare jambs, or old trim coming off
- Paint-grade or stain-grade, and the species if it has to match existing woodwork
- Paint or stain — painting is quoted as a separate line, or leave it primed and caulked and paint it yourself
What JMB supplies
- Extension jambs ripped to the wall depth where the window frame sits back from the drywall
- Casing in the profile that matches your doors, or a standard flat or colonial profile
- Miters cut on site to the actual corner, glued, and pinned across the joint
- Shims, fasteners, filler and paintable caulk
- Removal and haul-away of old stool, apron and casing when trim is being replaced
- Painting or staining of the new trim when you want it done, quoted as its own line
- Photos of the finished window in your job folder
How it is priced: per window
Quoted in writing from your photos within one business day. What moves the number:
- Whether the window needs extension jambs first or already has jambs flush with the wall
- Casing width and profile: flat stock is quick, a wide profiled casing takes more fitting at the miters
- Paint-grade vs. stain-grade hardwood matched to existing trim
- Openings out of square, which take shimming the jambs true before the frame goes on
- Removing old stool-and-apron trim and patching the wall where the horns were
- Windows close to a wall, cabinet or counter where one side of the casing has to be ripped narrower
- Number of windows in the same visit
Put a tape measure across the depth from the window frame to the wall in one photo. That tells us whether jambs are needed and sets the price.
How long it takes
About an hour per window once jambs are in, or two with jambs. A main floor in a day, primed and caulked.
How your project works
- 1
Send photos, get a written quote
Send three photos of the space and a sentence about what you want. You get a clear, itemized quote within one business day. We only come out to measure first when the job needs a tape measure — no pressure, no games.
- 2
Pick materials, or bring your own
We help you choose profiles and materials that fit the house and the budget, or match your existing millwork exactly — or you buy the door or trim yourself and we install it. Everything is confirmed before the crew is scheduled.
- 3
Clean, precise installation
The crew shows up on time, protects floors and furniture, and installs with tight joints and consistent reveals. Photos of the finished work go in your job folder.
- 4
Walkthrough and invoice
We walk the finished work with you. If anything is not right, we fix it before we call the job done. Then one invoice, paid by check or direct deposit — no card fees, no payment links.
Situations and options
Picture frame on drywall-return windows
The most common request in newer homes. The drywall wraps into the opening, so we add a wood jamb on all four sides flush with the wall, then case it. The bottom jamb replaces the soft drywall sill that chips, and the casing hides the edge.
Matching the door casing
We take the profile and reveal off a door in the same room and run the windows the same way. Most newer Twin Cities homes use a flat or colonial casing on the doors, and both stores and lumberyards stock the common ones. Odd profiles get matched from a sample.
Flat stock picture frame
Square-edged 1x boards, mitered. The cleanest modern look and the easiest miter to keep closed because the pieces are flat. Works in paint-grade poplar or MDF, or in oak, maple or walnut for stain.
Replacing stool and apron with a picture frame
Old trim comes off, the wall is patched where the stool horns ran onto it, the sill gets a jamb piece to match the sides, and the new frame goes on. Good for a room that is going modern, or for a window over a counter where the stool was in the way.
Picture Frame Window Casing — Mitered Trim on All Four Sides: questions, answered
What is picture frame window casing?
It is window trim that runs the same casing on all four sides of the window with mitered corners, like a picture frame, instead of casing on three sides sitting on a stool with an apron below. There is no ledge. The window jamb is flush with the wall on all four sides, the casing sits back from the jamb edge by an even reveal, and the four corners are cut at forty-five degrees. It is the same way most interior doors are cased.
Picture frame or stool and apron: which should I choose?
Picture frame if you want the windows to match the doors, the house is newer or the look is modern, or the window sits over a counter or tub where a ledge would be in the way. Stool and apron if you want a sill to set things on, the house is older and the other windows have one, or the window sits low enough that a ledge is useful. Both are priced per window; the stool-and-apron version takes a little longer because the stool is notched to the wall.
Why do the mitered corners on window trim open up?
Wood moves with humidity, and a Minnesota house swings from damp in July to bone dry in January. Each piece of casing shrinks a little across its width in winter, and at a miter that shows up as a gap at the outside corner. Miters that were only nailed open every year. Miters that were glued and pinned across the joint move together and stay closed. Setting the casing on a jamb that is truly flush with the wall matters too, because a jamb that is proud or shy twists the miter.
Can you put picture frame casing on a window with drywall returns?
Yes. A drywall return has no wood for the casing to land on, so we first add a jamb on all four sides, ripped to the depth from the window frame to the wall and set flush with the drywall. Then the casing goes on with an even reveal to the new jamb. The bottom piece of jamb replaces the drywall sill, which is the part of a return that always chips first.
Can you match the picture frame trim already in my house?
Yes. Send a close-up of a door or window casing with a tape measure across it and we identify the profile and width. Most of the flat and colonial casings in Twin Cities homes are still stocked at the lumberyards and big-box stores. If yours is discontinued, we can get close with a stock profile or have it run from a sample for a whole-house job. We also match the reveal so the new windows read the same as the doors.
Does picture frame casing work with a window sill I already have?
If the window has a stool now, the stool comes off for a true picture frame, because the horns stick out past where the side casing runs. We patch the wall where the horns were, add a bottom jamb to match the sides, and run the frame. If you like the stool and just want mitered casing on the top corners, that is a stool-and-apron trim with mitered head corners, and we do that too.
Get a written quote for this job
Three photos and a sentence is enough. You hear back within one business day. Or text the photos to 763-204-2099.
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Read morePage reviewed September 24, 2026 · JMB Builders LLC, MN license BC809005 · All window trim pages
Where we work
Window trim near you
Based in Zimmerman, scheduling across the Twin Cities metro. Closest first: