Sagging Garage Door Header Repair — Header Sistered or Replaced
The garage door rubs at the top in the middle, daylight shows at the corners of the top seal, and a level on the header trim reads a dip. The header is sagging and it will not get better on its own.
Sagging garage door header repair fixes the beam over an overhead door that has bowed until the door rubs and the top seal gaps at the ends. JMB Builders does it across the Twin Cities metro: we shore the opening, sister a new beam to the old header or replace it, reset the jack studs, jambs and trim, and add the missing drip cap. Priced per opening, quoted from photos within one business day.
- Priced per opening; single and double doors
- Header sistered or replaced with the wall shored
- Wide spans or a room above get an engineer's sizing
- Quote from photos in 1 business day
- Licensed MN contractor BC809005
The header over a garage door carries the wall above it, and on a lot of garages it also carries roof trusses or the floor of a room above. When it is undersized, when rot from a missing drip cap has eaten the bottom of it, or when someone cut into it for a loft, it bows. You see it first as a door problem: the door binds in the middle at the top, the top weather seal only touches at the ends, the opener strains. The door company adjusts the track and it comes back, because the opening is no longer square.
Sighting along the header trim from outside usually shows the dip. A string line from corner to corner confirms it. What matters after that is why. A solid header that sagged because it is too small for the span is a different repair from a header that is rotted through at the bottom from years of water running behind the trim. We check both from your photos and from a probe on site before we cut anything.
The repair is framing, not trim. We build temporary shoring under the load on both sides, pull the header trim and the top of the jambs, and either sister a new engineered beam to the existing header or take the header out and replace it. The jack studs under each end are checked and replaced if they are crushed or rotted. Then the jambs and trim go back, a drip cap goes over the head trim so the water problem is gone, and the door track and opener bracket are reattached to a header that is straight. On a wide double door, or any header with a room above it, the new beam gets sized by a licensed engineer.
What you supply
- A photo of the whole garage front and a close-up of the header trim, sighted from the side so the dip shows
- A photo from inside the garage of the header and the framing above it, with the door open
- The width of the door opening and whether there is living space over the garage
- Whether the wood above the door is soft when you push a screwdriver into it
- Your paint color if we are finishing the new trim; painting is quoted as a separate line, or paint it yourself
What JMB supplies
- Temporary shoring posts and a beam to carry the wall and roof load while the header is out
- Removal of the header trim, the top of the jambs and the rotted or bowed header
- A new LVL or built-up header, or a beam sistered to the existing one, sized to the span and the load above
- New jack studs and bearing blocks where the old ones are crushed, split or rotted
- Engineer's sizing letter for wide spans or a room above, brought in as its own line
- Jambs, stop molding and head trim reset in PVC or matched wood, with a drip cap over the head trim
- Door track brackets and the opener header bracket reattached to solid framing
- Photos of the framing before it is closed up in your job folder
- Painting of the new trim when you want it done, quoted as its own line
How it is priced: per opening
Quoted in writing from your photos within one business day. What moves the number:
- Single or double door width, which decides the beam and the shoring
- Sistering a beam to the existing header vs. removing and replacing it
- Rot in the header, jack studs or sheathing that has to be cut out and rebuilt
- A room or roof load above the door that needs an engineer to size the beam
- Siding type at the header, since stucco and brick take more work to open and close than lap siding
- Whether the door track and opener bracket can be reused or need new blocking
- New PVC trim and drip cap vs. reusing the existing trim
Send the inside photo with the door open. Seeing what sits on the header from inside tells us whether it is a sister job, a replacement, or one that needs an engineer, and the quote is firm from there.
How long it takes
Sistering a header on a single door: one day. Replacing the header on a double door: two days, shored overnight. Add lead time for an engineer's letter. Painting is quoted as its own line.
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
Sister a new beam to the header
The existing header is sound but too small for the span. We shore the wall, jack the old header back to straight, and bolt a new engineered beam to its face so the two carry the load together. Less demolition, and the siding above mostly stays.
Replace a rotted header
Water has run behind the head trim for years and the bottom of the header is soft. Shoring goes in, the header comes out with any rotted sheathing, a new beam and jack studs go in, and a drip cap over the new trim stops the water for good.
Wide door or room above
A double door with a bedroom over it, or a span that was never right. A licensed engineer sizes the beam and the bearing, then we build to the letter. The engineer's fee is a line on the quote.
Jamb and trim reset after the fix
Once the header is straight, the jambs, stop molding and head trim go back plumb and square so the door seals. We use PVC where the old trim rotted and match the profile on the rest of the garage.
Sagging Garage Door Header Repair — Header Sistered or Replaced: questions, answered
How do I know if my garage door header is sagging?
Stand to one side of the garage and sight along the trim above the door; a dip in the middle is a sagging header. Inside, open the door and look at the header with a string pulled tight from end to end. The door itself tells you too: it rubs at the top in the middle, the top seal only touches at the corners, and the opener labors. A door company can adjust around a small sag for a while, but it comes back.
Can a sagging garage door header be fixed without replacing it?
Often, yes. If the header is solid wood that is simply undersized, we shore the wall, jack the header back to straight, and sister a new engineered beam to it so the two carry the load together. That keeps most of the siding and sheathing in place. A header that is rotted or split has to come out and be replaced.
Why did the garage door header rot?
Almost always because there was no drip cap over the head trim. Rain runs down the siding, behind the trim, and sits on the bottom of the header, which is end grain at the joints and never dries. We fix that as part of the repair: new trim goes on with a metal drip cap above it and flashing tape behind it, so the new header stays dry.
Do I need an engineer for a garage door header?
For a double door, or any header that carries a room or a roof load above it, yes. A licensed engineer sizes the new beam and the bearing under it, and we build to the letter. We bring the engineer in and the fee is its own line on the quote. A single door header carrying only the wall above it is usually a standard beam and does not need one.
Will the garage door work right after the header is fixed?
The track brackets and the opener header bracket go back on solid framing, and with the opening square again the door should run without binding. If the door was adjusted to compensate for the sag, the springs or the opener travel may need to be reset, and that is the garage door company's work; we tell you if we see it.
Does the garage door have to come out?
Usually not. The door stays on its track in the down position while we work above it, and the shoring goes on either side. On a header replacement the track brackets come off for a day and go back on. If the door itself is damaged or the opener is failing, we say so, but the header repair does not require a new door.
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 27, 2026 · JMB Builders LLC, MN license BC809005 · All exterior trim pages
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