Patio Door With Transom Replacement — Door and Transom as One Unit
Your patio door has a window above it and the two are one opening. Replacing only the door leaves an old transom, an old joint and the leak that usually started there.
Reply within one business day. Or call / text 763-204-2099.
Patio door with transom replacement means the sliding or French door and the fixed glass above it come out and go back in as one flashed opening, either as a factory-mulled unit or as a new door with a matching transom set on top. JMB Builders measures the full opening, orders the pair to match, and installs it across the Twin Cities metro with one flashing line from sill to head. Priced per door, reply within one business day.
- Priced per door, door and transom included
- Factory-mulled unit or door plus matched transom
- One flashing line from the sill to the transom head
Great rooms and walkout living rooms built from the 1980s on often have a patio door with a transom: a fixed pane above the door that carries the glass up toward a vaulted ceiling. The door and the transom share one rough opening. They are either a single factory unit joined with a mull bar, or two separate units stacked with a joint between them. Either way, the weak point is that horizontal joint. It takes water running down the glass and, on a south or west wall, a lot of sun.
When the door needs replacing, the transom usually does too. The seals are the same age, the frame is the same material, and a new white door under a yellowed old transom looks like exactly what it is. More important, the flashing between them is only right if both units go in together: sill pan under the door, flashing tape up the jambs, across the mull, and up to the head of the transom in one shingled sequence.
We measure the whole opening, order the door and transom as a mulled unit when the manufacturer offers it in your size, or as two matched units when it does not, and set them as one opening. Options such as Andersen, Pella, Marvin and ProVia all make door-and-transom combinations in sliders and hinged French pairs.
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
- Slider or French pair for the door, and whether the transom stays clear, gets grilles or matches a grille pattern on the door
- Frame material and color: vinyl, fiberglass or clad wood, same for the door and the transom
- Photos showing the full height of the opening inside and out, including the joint between door and transom
- Paint or stain color for the new casing — finishing is quoted as its own line
What JMB supplies
- Measurement of the full rough opening, including the transom, before the order
- The door and transom as a factory-mulled unit or two matched units, with screen
- Removal and haul-away of the old door, transom, frame and trim
- Sill pan, flashing tape from sill to transom head, backer rod, low-expansion foam and sealant
- Framing or subfloor repair at the sill or the old mull joint, quoted from the photos
- Interior casing around the whole opening and exterior trim or brickmould
- Painting or staining of the new casing when you want it, quoted as a separate line
- Photos of the finished opening in your job folder
How it is priced: per door
Quoted in writing from your photos, with a reply within one business day. What moves the number:
- Slider vs French pair, and the width of the door
- Transom height and whether it is a stock or custom size
- Factory-mulled unit vs two units joined on site
- Frame material and color, and the glass package in both units
- Rot at the sill or water damage at the old mull joint once the units are out
- Working height: a transom in a vaulted room may need staging inside and out
- Painting or staining the new casing, quoted as a separate line
Send one photo from across the room showing the whole opening floor to top, one from outside, and a close-up of the joint between the door and the transom. Add a rough overall height.
How long it takes
One slider with transom in a sound opening: a full day on site, sometimes into a second morning for trim. Mulled units are built to order and arrive several weeks after the quote is approved.
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
Factory-mulled door and transom
The door and the transom leave the factory as one unit joined by a structural mull. One frame, one flashing job, one set of reveals. Available in most slider and French door lines up to the manufacturer's height limit; we check your opening against it.
Door plus separate matched transom
Two units from the same line, stacked on site with a flashed mull joint between them. Used when the opening is taller than a mulled unit can be, or when the transom shape is an arch or a trapezoid that is not offered mulled.
Transom-only replacement with a newer door
If the door was replaced recently and only the transom has failed, we match a new transom to the existing door's line and color and reflash the joint. Only worth it when the door is the same material and the color is still made.
Patio Door With Transom Replacement — Door and Transom as One Unit: questions, answered
Do I have to replace the transom when I replace the patio door?
Not always, but usually it is the right call. The transom is the same age as the door, the joint between them is the leak point, and a new door under an old transom does not match. If the transom is only a few years old and from a line still in production, we can match the door to it and reflash the joint. Send photos and we will tell you which case you are in.
Why does water come in between my patio door and the transom?
The horizontal joint between the two units takes every drop that runs down the transom glass. If it was sealed with caulk alone and no flashing behind it, the caulk eventually splits and water tracks into the head of the door frame and down the jambs. Replacing both units together lets us run flashing tape from the sill pan up the jambs and across the joint in one continuous shingled line.
Can the transom have grilles that match the door?
Yes. Order the transom in the same line as the door and the grille pattern, bar width and color carry across. A common choice is a clear door with a divided-lite transom, or matching grilles on both. If the room has a vaulted ceiling, a clear transom keeps the view and the light; grilles are a style choice, not a structural one.
Is a patio door with transom a custom order?
The door part is usually a stock size. The transom height is what makes it custom, because the total opening height varies house to house. Most manufacturers build mulled door-and-transom units to the quarter inch, so the order is custom but not exotic. Expect several weeks from approval to delivery, and we do not pull the old opening until the new unit is here.
Can you replace a French door with transom instead of a slider?
Yes. Hinged French pairs come with transoms the same way sliders do, mulled or stacked. The opening width and the swing room inside or out decide whether a French pair fits; the transom does not change that. We can also swap a slider-with-transom for a French-pair-with-transom in the same opening if the width works.
How tall can a mulled patio door and transom be?
Each manufacturer sets a maximum height for a factory-mulled unit, and most two-story great room openings fall within it. When the opening is taller, we order the door and transom separately and join them on site with a flashed mull. Either way the glass package, color and grilles match. We measure the full opening before ordering so the right version is quoted.
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 10, 2026 · JMB Builders LLC, MN license BC809005 · All doors pages
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