Garage Service Door Replacement — Steel Man Door on the Garage
The garage side door is rusted through at the bottom, the jamb is soft, and it has not locked properly in years. A steel prehung unit, set right on a sill pan, and it is done for another few decades.
JMB Builders does garage service door replacement across the Twin Cities metro: the walk-through door on the side or back of the garage, not the overhead door. We pull the old door and jamb, repair the rot at the sill that is almost always there, set a steel prehung unit in a sill pan with flashing, trim it with brickmould, and install the lockset and deadbolt. Priced per door, quoted from photos within one business day.
- Priced per door; you buy it or we supply it
- Sill rot repair, sill pan and flashing included
- Quote from photos in 1 business day
- Licensed MN contractor BC809005
The garage service door is the most neglected door on the property. It sits at grade or a step above it, snow piles against it, the sprinkler hits it, and it was often a cheap wood door to begin with. By the time someone calls, the bottom rail is rusted or rotted, the jamb legs are soft, the threshold is gone and the deadbolt no longer lines up. It is also the door burglars try first, because it is out of sight.
The replacement is a steel prehung exterior unit, the same kind of door that goes on a house. The old door, jamb and brickmould come out, the rough opening is checked and the rotted sill plate or subfloor at the bottom is cut out and replaced, then the new unit goes in on a sill pan with flashing tape up the sides, shimmed at the hinges and strike, foamed, and trimmed with brickmould outside and casing inside if the garage is finished. A lockset and deadbolt go on, keyed to the house if you want.
JMB Builders replaces garage service doors on attached and detached garages across the Twin Cities metro. This page is the exterior walk-through door on the garage. The door between the garage and the house is a rated door with its own rules and its own page.
What you supply
- A photo of the door from outside a few feet back, one close-up of the bottom of the door and jamb, and one from inside
- The door if you buy it: a steel prehung exterior unit in the right hand and jamb width; send the label before ordering and we check it
- Lockset and deadbolt, or tell us to supply them keyed to your house key if the brand matches
- Paint for the door and trim, or add painting as a line on the quote
What JMB supplies
- The steel prehung unit when you want us to supply it, in a standard size and hand for the opening
- Removal and haul-away of the old door, jamb, brickmould and threshold
- Rot repair at the sill plate, subfloor or jack studs, quoted from the photos
- Sill pan, flashing tape, shims, low-expansion foam and exterior sealant
- Brickmould or PVC exterior trim, and interior casing where the garage is finished
- Lockset, deadbolt and strike plates installed, with long screws into the framing
- Sweep and threshold adjusted so the door seals against the wind and snow
- Photos of the finished door in your job folder
How it is priced: per door
Quoted in writing from your photos within one business day. What moves the number:
- You supply the door vs. we supply it
- Rot at the sill: none, a small subfloor patch, or a rotted sill plate and jack studs to replace
- Whether the new door is the same size as the old one or the opening has to be resized
- Siding at the door: vinyl or steel siding that needs J-channel worked around vs. wood that takes brickmould directly
- Exterior trim: standard brickmould vs. PVC trim to match the house
- Hardware: reuse yours, a basic lockset and deadbolt, or a keyed-alike set to match the house
- Detached garage without power for tools, or a long walk from the truck
Send the three photos and, if you have bought the door, a photo of the label. The quote covers the door install, the trim and the rot repair we can see, with no allowances.
How long it takes
One garage service door, same size as the old one: about half a day. Add a couple of hours when the sill plate or subfloor has to be rebuilt.
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
Steel prehung, same size
The standard job. A six-panel or flush steel exterior unit, primed, in the same size as the old door. Out with the old, rot repair, sill pan, set, foam, trim, hardware. Done in a morning.
Door with a window
A half-lite or nine-lite steel door lets light into a garage with no windows. Same install; the glass is factory-set in the door. Choose a door with an obscure glass if the garage faces the street and you would rather not show what is inside.
Fiberglass instead of steel
Fiberglass does not rust at the bottom rail the way steel eventually does where snow sits against it. It costs more and is worth it on a door that gets buried every winter. Installed the same way.
Resize the opening
Old garages sometimes have a narrow or short service door. We can reframe the opening to take a standard door so you are not stuck with a special order, which usually means a new header and a day instead of a half day.
Garage Service Door Replacement — Steel Man Door on the Garage: questions, answered
What kind of door should I buy for a garage side door?
A steel prehung exterior door in a standard size, primed, with the jamb width that matches the garage wall. It is the same type of door that goes on a house entry and it comes with the threshold and weatherstrip attached. Get the hand right: stand outside, and if the hinges will be on your right when the door swings in, that is a right-hand inswing. Send a photo of the old door before you buy and we confirm the size and hand for free.
Why is the bottom of my garage service door rotted?
The door sits at grade, snow piles against it all winter, and the melt runs under the threshold into the sill plate. Most garage service doors were installed without a sill pan or flashing, and many were wood doors to begin with. Once the sill plate is wet, the jamb bottoms and the door rail follow. When we replace the door, we cut out the rotted sill and put the new door on a sill pan so it drains.
Can you replace the garage service door on a detached garage?
Yes. Detached garages are the usual case, and they tend to have the worst rot because nobody looks at that door. We bring power for the tools if the garage has none. The work is the same: old door out, sill repaired, new steel unit set on a sill pan, trimmed and locked.
Can the new garage door lock be keyed to my house key?
Usually, if the lock brand is the same as the house locks or you buy a set from that brand. We install the lockset and deadbolt you supply, or bring a keyed-alike set and match it to your house key at the counter. Either way the deadbolt strike gets long screws into the framing, since the service door is the one people try to kick.
Is the garage service door the same as the door from the garage into the house?
No. The service door is the exterior walk-through door on the outside wall of the garage and is a standard exterior door. The door between the garage and the house has to be a rated, self-closing unit and has its own page. If both need replacing, we do them in the same visit.
How long does it take to replace a garage side door?
About half a day when the new door is the same size as the old one. Pulling the old unit, cutting out a rotted sill plate and rebuilding it adds a couple of hours. Resizing the opening for a standard door is a full day. The door goes in primed; painting is quoted as a separate line, or paint it yourself.
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 doors pages
Where we work
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Based in Zimmerman, scheduling across the Twin Cities metro. Closest first: