Picture Window With Casement Flankers — Sizing, Hinges and Sightlines
You want the big front window to open on the sides, or the one you have already does and you want the new one laid out better: wider view, better breeze, matching frame lines.
Reply within one business day. Or call / text 763-204-2099.
A picture window with casement flankers is a fixed center unit with a crank-out casement on each side, joined into one mulled assembly. JMB Builders works out the flanker width, which way each casement swings and how the frame lines up before ordering, then replaces the whole assembly in one piece across the Twin Cities metro. Priced per opening; photo reply within one business day, or a free in-home estimate.
- Priced per opening, each unit listed
- Flanker width and hinge side set before ordering
- Replaced as one mulled assembly
This layout is on thousands of Twin Cities houses: the front window, a wide fixed pane in the middle, and a narrow casement at each end that cranks out. The center gives the view. The flankers give air. Ordering one is not hard, but a few choices made at the measure decide whether the new unit looks right from the curb and works in the room.
First, the split. Flankers can be narrow so the center glass is as wide as possible, or wider so they move more air. Second, the swing. Each casement can be hinged on its outside edge, so the open sashes frame the picture window and scoop a breeze toward the middle, or the other way. Third, the sightlines. The fixed unit's frame is thinner than a casement's, so on some lines the glass in the center sits at a different height than the flankers. Many lines offer a matching frame so the glass lines up across all three.
Whatever the layout, the three units go in as one mulled assembly under one header, flashed across the full width. The old unit comes out in one piece. Egress rarely matters on a front living room window; if this window is in a bedroom, one flanker is sized for it.
Get a written quote for this job
Three photos and a sentence is enough: a reply within one business day, or ask for a free in-home estimate. Or text the photos to 763-204-2099.
What you supply
- The split you want: narrow flankers for view, or wider ones for air
- Which way each casement opens, or ask us to pick for the breeze
- Frame color, grille pattern (or none) and interior finish
- Furniture moved back from the window wall, or we move it
What JMB supplies
- One in-person measure of the full opening and a sketch of the split before ordering
- Center unit and both casements on one order, mulled with reinforcement where the width calls for it
- Old assembly removed in one piece, floor and furniture covered
- Sill pan, flashing and sealant across the full width; header checked for sag
- Interior stool run across all three units, casing and apron, or jamb extensions
- Exterior capping or trim, haul-away and photos in your job folder
- Painting quoted as a separate line — or leave it primed and caulked and paint it yourself
How it is priced: per opening
Quoted in writing from your photos, with a reply within one business day. What moves the number:
- Overall width and height, and the size of each flanker
- Matching sightline frames vs. standard fixed and casement frames
- Insert into the old frame vs. full-frame removal
- Changing from a single picture window to a three-unit layout in the same opening
- Tempered glass where a low sill or nearby door calls for it
- Rot in the sill or a sagging header found at the measure
Send a photo of the whole window from the street and from inside, and a tape measurement across the inside trim if you can.
How long it takes
One picture-and-flanker assembly: one day, closed up before dark. Lead time depends on the brand and is written on the quote.
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 reply within one business day. Prefer a look in person? A free in-home estimate is always an option.
- 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
Narrow flankers, wide view
Casements just wide enough to vent, with the most glass in the center. Suits a window facing a lake, a park or a long view.
Equal thirds
Three units the same width, the center one fixed. Reads as one balanced window from the street and moves the most air.
Flankers hinged on the outside
Each casement hinges at its outer edge, so the open sashes stand like wings beside the center glass and catch a side breeze.
Awnings under the picture instead
Where a walkway or shrubs sit right outside, awnings below the fixed glass vent without a sash swinging out to the side.
Picture Window With Casement Flankers — Sizing, Hinges and Sightlines: questions, answered
How wide should the casement flankers be on a picture window?
Wide enough to move air, narrow enough to keep the view. On a typical front window the flankers run roughly a quarter of the width each, or the three units are equal for a balanced look. We sketch both at the measure so you can see where the frame lines fall against your view.
Which way should casement flankers open?
Most people hinge each one on its outside edge, so both sashes open away from the center glass and frame it. A casement catches wind best when it opens toward the breeze, so on a windy side it can make sense to hinge both the same way. We note the hinge side for each unit on the order.
Will the glass line up between the picture window and the casements?
Not always. A fixed unit has a thinner frame than a casement, so on some lines the glass in the center sits larger and at a different height. Many window lines offer a fixed unit built with a casement-style frame so all three glass edges line up. We tell you which you are getting before you order.
Can I replace just one of the casements beside my picture window?
It is possible on some units but rarely worth it. The joint between the old and new frames is where leaks start, and the colors will not match. The assembly is usually replaced as one, priced with each unit listed.
Can a single picture window be changed to one with opening sides?
Yes, in the same opening. The new assembly is a narrower fixed center with a casement on each side, sized to the rough opening. You lose a little glass to the extra frames and gain air on both ends.
Do the screens go inside or outside on casement flankers?
Inside. A casement cranks outward, so its screen sits on the room side of the sash. The fixed center has no screen. That leaves the outside of the whole window clean, with no screen frames on the curb side.
Recent JMB work, from our job log
59 installs recorded across 30 Twin Cities communities since Dec 2025. Window and door installs for homeowners and the builders we work with. Counts come straight from our job log; no customer names.
Related jobs we do
Picture Window Replacement — Large Fixed Glass Set and Trimmed
A fogged living room window, a picture window that frosts at the bottom, or an old unit you want to open up with casements. We replace it and finish the trim.
Read moreReplace a Triple Window Unit — Mulled Twins and Triples as One
You have two or three windows joined into one wide unit — triple casements, twin double-hungs or a picture window with casements — and the whole thing is failing.
Read moreLiving Room Window Replacement — Picture Unit, Flankers, View Glass
The front window is the one everybody sees from the street and the one you look through every evening: fogged, drafty, or just the wrong glass for a west-facing room.
Read moreCasement Window Replacement — Crank-Out Windows Measured and Installed
The crank strips, the sash will not pull tight, frost builds on the glass edge. When the casement itself is done, we replace it and finish the trim.
Read moreCasement or Awning Windows for Ventilation? Picking the Crank-Out
The house has no central air, or you just like a breeze, and the old windows barely open. Both crank-out styles seal tight in winter; they move air very differently in summer.
Read more1.5 Story Dormer Window Replacement — Upstairs Knee Wall Bedrooms
The upstairs windows in the dormers are drafty and hard to reach, and the bedrooms up there are the coldest rooms in the house.
Read morePage reviewed October 9, 2026 · JMB Builders LLC, MN license BC809005 · All windows pages
Where we work
Window Replacement & Installation near you
Based in Zimmerman, scheduling across the Twin Cities metro. Closest first: