Add a Window to an Existing Wall — or Make a Window Bigger
A dark room, a kitchen wall with no view, or a window too small for the space. We cut a new opening or enlarge the old one and finish both sides.
JMB Builders can add a window to an existing wall, or make a window bigger, across the Twin Cities metro. We lay out the opening, cut the wall, frame it with a header sized for the span, set and flash the new window, patch the siding outside and the drywall inside, and trim it out. Permit pulled when needed. Priced per opening, quoted from photos, measured in person.
- Priced per opening, window supplied
- Header, siding and drywall patch included
- Permit pulled when the city requires one
- Licensed MN contractor BC809005
Adding a window or making one bigger is framing work first and window work second. The studs that come out were carrying something, so a header goes over the opening, sized for the span and the load above it. Then the new window is set in a sill pan and flashed into the wall, the siding is patched around it, and the inside is drywalled and trimmed.
Before we cut, we check what is in the wall: wires, plumbing, ducts, and whether the wall is load-bearing. Wiring in the way is moved by a licensed electrician. On a bearing wall with a wide opening, or anything unusual above, the header is sized by an engineer. Most cities require a permit for a new or wider opening in an exterior wall; we apply for it.
What you supply
- Where you want the window and roughly how big
- Your choice of window style, brand, color and glass
- Furniture moved and wall decor off the wall inside
- Your paint colors — Painting is quoted as a separate line — or leave it primed and caulked and paint it yourself.
What JMB supplies
- Layout and a check of the wall for wiring, plumbing, ducts and load
- Permit application where the city requires one
- The window, ordered to the new opening size
- Wall cut, framing, header, jack and king studs, and sill
- Sill pan, flashing tape tied into the housewrap, foam and sealant
- Siding patch outside and drywall patch inside, taped and ready for paint
- Interior casing or returns and exterior trim
- Photos of the finished opening in your job folder
How it is priced: per opening
Quoted in writing from your photos within one business day. What moves the number:
- New opening vs. enlarging an existing window
- Width of the opening and whether the wall is load-bearing
- What is in the wall: wiring, plumbing or ductwork to move
- Exterior cladding to cut and patch: lap siding, stucco or brick
- Window size, style, brand and glass
- Interior finish: drywall patch, returns or new casing, and paint
- Permit and engineering where required
Send a photo of the wall inside and outside and mark roughly where you want the window.
How long it takes
Most openings in a lap-sided wall: one to two days to frame, set the window and patch, plus a return visit to finish drywall. Permit lead time comes first where one is needed.
How your project works
- 1
Photos and a quote
Send photos of the wall inside and out with the spot marked. You get a written quote within one business day.
- 2
Site check and permit
We check the wall for load, wiring and plumbing, confirm the window size, and apply for the permit where required.
- 3
Cut, frame and set
Wall opened, header and framing in, window set in a sill pan, flashed into the wrap, and the opening closed the same day.
- 4
Patch and trim
Siding patched outside, drywall patched and finished inside, then casing or returns. Inspection where a permit was pulled.
Situations and options
Add a window to a blank wall
A new opening where there was none. We pick a spot between studs where we can, frame it with a header, and patch both sides.
Make an existing window bigger
Wider, taller, or lower to the floor. The old window and framing come out, a longer header goes in, and the siding and drywall are rebuilt around the new size.
Make a window smaller
The opening is framed in, a smaller window is set, and the siding and drywall are closed up. Common in bathrooms and kitchens getting new cabinets.
Add a Window to an Existing Wall — or Make a Window Bigger: questions, answered
Can you add a window to an existing wall?
Yes. The wall is opened, framed with a header, and the new window is set and flashed into it. The siding is patched outside and the drywall inside. We check for wiring, plumbing and load before we cut.
How do you make a window bigger?
The old window and the framing around it come out, the opening is cut to the new size, and a longer header goes in to carry the wall above. The new window is set and flashed, then the siding and drywall are rebuilt around it.
Do I need a permit to add a window?
Most Twin Cities cities require a building permit for a new or enlarged opening in an exterior wall. We apply for it where it is needed and schedule the inspection.
Can a window go in a load-bearing wall?
Yes. The header over the opening carries the load the removed studs carried. For wider openings or unusual loads above, the header is sized by an engineer.
What if there are wires in the wall where I want the window?
Wiring in the way is rerouted by a licensed electrician before the opening is cut. Outlets or switches under a new window may need to move. It is listed on the quote.
Will the siding patch show around a new window?
On lap vinyl or fiber cement, pieces can usually be matched or borrowed from a hidden wall. On old or faded siding the new pieces can look different until painted. We talk through it before we cut.
Can you make a window smaller for a kitchen remodel?
Yes. It is common when new cabinets or a counter backsplash run under a window that is too tall. The old window comes out, the opening is framed in at the bottom (or the side) to the new size, a new window goes in, and the siding outside and drywall inside are patched. The header stays, so no structural change is needed in most cases. JMB pulls the permit when the job needs one.
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 for the builders and dealers we sub for. Counts come straight from our job log; no customer names.
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 26, 2026 · JMB Builders LLC, MN license BC809005 · All windows pages
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Based in Zimmerman, scheduling across the Twin Cities metro. Closest first: