Match New Windows on Addition to Existing House — One Window Order
The addition gets new windows anyway. If the old ones are near the end, order the house with it, so nothing on the outside looks newer than the rest.
Reply within one business day. Or call / text 763-204-2099.
To match new windows on an addition to the existing house, order both as one package: nailing-fin windows for the addition's new walls and replacement windows for the old openings, same brand and series, same color, glass and grilles. JMB Builders measures both, installs the addition windows once the rough openings are framed, and replaces the house windows room by room across the Twin Cities metro. Priced per project; photo reply within one business day or a free in-home estimate.
- Priced per project, addition and house listed
- One order: color, glass and grilles match
- Addition sill and head heights lined up
Matching addition windows to twenty-year-old windows is hard. Frame colors fade, lines get discontinued, and the glass on the new side reads differently. If the existing windows are already on your list, the cleanest answer is to do the house and the addition on one order.
The two sides go in differently. Addition walls are new framing, so those windows are usually nailing-fin units set in the rough opening, flashed to the wrap and sided over. The house openings get replacement windows, insert or full frame, without tearing up the finished walls. Many lines come in both versions; we confirm the series you pick does before you choose it.
We also line things up you would notice later: head heights across the joint, sill heights in rooms that open into the addition, and grille patterns on the wall facing the street. Whoever frames the addition gets the rough opening sizes from the order, so the windows fit the walls and not the other way around.
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
- Addition plans or drawings showing window locations
- Who is framing the addition, and their schedule
- Brand, series, color, glass and grilles for both sides
- Paint colors — Painting is quoted as a separate line — or leave it primed and caulked and paint it yourself.
What JMB supplies
- One measure of the existing openings and a takeoff from the addition plans
- One order: addition windows and house replacements, same spec
- Rough opening sizes for the framer before walls go up
- Addition windows set, flashed to the wrap, ready for siding
- House windows replaced room by room, each closed the same day
- Interior trim matched on both sides of the joint
- Photos of both in your job folder
How it is priced: per project
Quoted in writing from your photos, with a reply within one business day. What moves the number:
- Number of addition windows and house windows
- Brand and series, and whether it comes in both nailing-fin and replacement versions
- Insert vs. full frame on the existing house
- Sizes and specialty shapes on the addition
- Exterior trim and siding work around the house openings
- Interior trim scope on both sides
Send the addition plans and a photo of each existing window, labeled by room.
How long it takes
Lead time depends on the brand and is written on the quote; order early so addition windows are on site when the framing is done. House windows install over several working days.
How your project works
- 1
Plans and photos
Addition plans plus a photo of each house window. We reply within one business day, or book a free in-home estimate.
- 2
Measure and takeoff
House openings measured in person; addition windows taken off the plans and checked against framing.
- 3
One order, rough openings out
Both sides ordered together. Rough opening sizes go to whoever frames the addition.
- 4
Addition, then house
Addition windows set as soon as the walls are wrapped. House windows replaced room by room on their own schedule.
- 5
Trim and walkthrough
Trim matched across the joint, every window operated with you, photos in your job folder.
Match New Windows on Addition to Existing House — One Window Order: questions, answered
How do you match addition windows to existing windows?
The surest way is to replace the existing windows at the same time, on the same order. If you keep the old ones, we try to match brand, series, color and grilles, but fading and discontinued lines can make an exact match impossible. We tell you how close it will be before you order.
Should I replace old windows when building an addition?
If they are near the end of their life, it is the best time: one order, one color, and the outside reads as one house. If they are in good shape, matching the addition to them is often fine.
Are addition windows the same as replacement windows?
Often not. Addition walls are new framing, so nailing-fin windows are usual. Existing openings get replacement windows that fit the old frame or opening. Many series come in both versions, which is how both sides match.
Who gives the framer the rough opening sizes?
They come from the window order. We send them to whoever frames the addition before the walls go up, so the windows fit the openings.
Can you install windows in an addition someone else is building?
Yes, as long as the schedule is coordinated with whoever is running the addition. We set and flash the windows once the walls are framed and wrapped, ready for siding.
Do I need a permit for addition windows?
The addition itself is permitted, and the windows are part of it. Replacement windows in the existing house often do not need a separate permit, but some cities require one. JMB pulls permits when needed.
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.
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Read morePage reviewed October 9, 2026 · JMB Builders LLC, MN license BC809005 · All whole-house projects pages
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