Therma-Tru Door Installation, Labor Only — Fiberglass Entry Doors
You picked the Therma-Tru because it will not dent or rust like the steel door it is replacing. It still has to go in plumb, on a pan, with the sill adjusted right, or the fiberglass does not matter.
Who installs Therma-Tru doors a homeowner already bought? JMB Builders does, labor only, across the Twin Cities metro. We are an independent installer, not a Therma-Tru dealer. Smooth-Star or Fiber-Classic from a lumberyard, Benchmark from Lowe's: we pull the old door, set the new prehung on a sill pan, shim every hinge, drive long screws into the framing, seal it, hang your lock and case it. Priced per door, quoted from photos in one business day.
- Priced per door, labor only
- Smooth-Star, Fiber-Classic, Benchmark units
- Independent installer, not a Therma-Tru dealer
- Licensed MN contractor BC809005
Therma-Tru fiberglass doors come to us three ways: a Smooth-Star or Fiber-Classic unit ordered through a lumberyard millwork desk, a Benchmark unit off the rack at Lowe's, or a special order with sidelites and a transom that showed up on a pallet. In every case the homeowner owns the door and needs a carpenter. We are an independent installer, not a Therma-Tru dealer; the product, its specs and its paperwork belong to the maker and the seller. The install is ours.
A fiberglass door is lighter than a wood door and stiffer than a steel one, and the frame is what makes or breaks it. Most units ship with a composite or rot-resistant jamb bottom and an adjustable sill. We set the unit in a sill pan, plumb the hinge jamb first, shim behind every hinge, and run long screws through the hinges into the stud so the door does not sag under a glass lite. Then the sill gets adjusted up to the sweep, the weatherstrip is checked with a dollar bill all the way around, and the outside is sealed.
The one thing to know before the door arrives: most Therma-Tru fiberglass doors come unfinished or primed, not painted. The skin has to be stained with a gel stain kit or painted before it sits through a Minnesota summer. We quote that as its own line, or you can finish it yourself once it is hung.
What you supply
- The Therma-Tru prehung unit: correct handing, jamb width for your wall, and rough-opening size
- Lockset and deadbolt (the unit ships bored for them but they are sold separately); handle set if it is a multipoint lock
- Brickmould or exterior trim if you want a profile other than what came on the unit
- Your stain or paint color for the door skin and new casing if we are finishing it; that is quoted as its own line
What JMB supplies
- A check of your lumberyard or Lowe's order against the opening before it ships, no charge
- Removal and haul-away of the old door, jamb, casing and threshold
- Sill pan, flashing tape, shims, long hinge screws, low-expansion foam and exterior sealant
- Subfloor or framing repair at the sill when we find rot, quoted first
- Interior casing in a standard profile or matched to the house; exterior trim fitted and sealed
- Lockset, deadbolt and strike installed and the sill adjusted to the sweep
- Photos of the finished door in your job folder
- Staining or painting the fiberglass skin and trim as its own line, or finish it yourself
How it is priced: per door
Quoted in writing from your photos within one business day. What moves the number:
- Single door vs. a unit with one or two sidelites or a transom, which is wider, heavier and slower to set square
- Rot at the sill or the bottom of the old jambs, common on entry doors over a stoop
- Whether the rough opening matches the new unit or has to be reframed
- Exterior trim: reusing the brickmould on the unit vs. new trim to match the house
- Finishing the door skin and casing, quoted as its own line
- A second door, such as a garage service door, in the same trip
Send a photo of the old door from outside and inside, one of the sill and the bottom of the jambs, and the Therma-Tru order sheet or the sticker on the unit.
How long it takes
A single Therma-Tru prehung: about half a day. A door with sidelites or a transom: most of a day. Finishing the skin adds a day for stain to cure before the door is closed up.
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
Smooth-Star and Fiber-Classic from a lumberyard
Paintable smooth skins and stainable wood-grain skins ordered through a millwork desk, usually with a composite jamb and adjustable sill. We check the order before it is final so the handing, jamb width and rough opening arrive right.
Benchmark by Therma-Tru from Lowe's
The stock fiberglass units on the rack, in common sizes and a few glass options. Same install as the lumberyard doors: pan, plumb hinge jamb, long screws, foam, seal, case. Bring the lock home with the door so the bore matches.
Doors with sidelites and transoms
A mulled unit is one big frame that has to go in as a piece. We bring two people, check the rough opening before delivery, and set it so the sidelite glass is plumb and the door swings without touching the mull.
Fiberglass over an old steel door
The common swap: a dented, rusting steel door out and a Therma-Tru in the same opening. We check for rot behind the old threshold, fix it, then set the new unit and reuse or replace the exterior trim.
Therma-Tru Door Installation, Labor Only — Fiberglass Entry Doors: questions, answered
Who installs Therma-Tru doors in the Twin Cities?
JMB Builders installs Therma-Tru fiberglass entry doors homeowners have already bought, labor only, across the Twin Cities metro. We are an independent licensed Minnesota contractor, not a Therma-Tru dealer. You buy the unit through a lumberyard or Lowe's; we check the order against your opening, remove the old door, set the new one on a sill pan, seal it, install your lock hardware and case it. Priced per door, quoted from photos within one business day.
Does a Therma-Tru fiberglass door come finished, or do I need to paint or stain it?
Most come primed or unfinished. Smooth skins are meant to be painted; wood-grain skins are meant to take a gel stain and a clear topcoat. Some special orders can be factory finished, and the order sheet will say. If yours is unfinished, it needs a coat before it sits through a summer of sun, and we quote finishing as its own line, or you do it after we hang it. Either way, we install it first so the finish is not scuffed on the way in.
Can you install a Therma-Tru door with sidelites and a transom?
Yes. A door with sidelites usually arrives as one mulled frame, sometimes with the transom as a separate piece that stacks on top. It is heavy and wide and has to be set plumb across the whole assembly, so we bring two people and check the rough opening before the unit is ordered. The exterior trim around a wide unit is usually new, since the old single-door brickmould will not fit.
What is different about installing a fiberglass door versus a steel one?
The steps are the same, but fiberglass does not flex, so the frame has to be plumb and the hinges shimmed tight or the door will not seat evenly on the weatherstrip. Fiberglass skins also cannot be trimmed if the door is the wrong size; a prehung fiberglass unit has to fit the rough opening as ordered. And unlike a prefinished steel door, the fiberglass skin usually needs stain or paint after install.
Are you a Therma-Tru dealer?
No. We are an independent installer and a licensed Minnesota residential building contractor, BC809005. We do not sell Therma-Tru doors, and we make no claims about the product beyond what the manufacturer prints. The door, its specs and its warranty paperwork come from Therma-Tru and the store that sold it. The install, the flashing and the trim are our work.
What do I need to order with the Therma-Tru door?
A lockset and deadbolt in the finish you want; the unit is bored for them but does not include them. If the door has a multipoint lock, the handle set is specific to it. Check the order for the jamb width that matches your wall, the handing, and whether brickmould is included on the outside. Interior casing is never included; we bring it. Send us the order sheet before you sign it and we check all of that.
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.
Related jobs we do
Feather River Door Installation — Home Depot Fiberglass Entry Doors
The Feather River door with the glass you picked out is on a pallet in the garage, wrapped in cardboard. We unwrap it, check it, and hang it so the glass sits plumb and the door closes with one finger.
Read moreReliaBilt Door Installation — Lowe's Entry, Interior and Storm Doors
ReliaBilt is the door on the Lowe's rack in the size you need, today, at a price that makes the install the bigger question. We hang it right so the low price stays a good deal.
Read moreMastercraft Door Installation, Labor Only — Menards Prehung Doors
The Mastercraft door came home on the rebate weekend and has been leaning in the garage since. We set it in a morning, with the pan and foam Menards did not sell you.
Read moreLabor-Only Door Installation — We Install the Door You Bought
You buy the door, we install it right — entry doors, house-to-garage doors, and interior doors hung plumb, sealed tight, and trimmed out by a licensed Minnesota contractor.
Read moreRotted Door Trim Replacement — Casing, Brickmould & Flashing
The paint is bubbling at the bottom of the door casing and a screwdriver sinks right in. We replace the rotted trim and fix the water path that caused it, so it stays fixed.
Read moreAndersen 100 and 400 Series Window Installation, Labor Only
The Andersen order is at the store or stacked on your driveway and the store's install program is weeks out. We set each window the way the printed guide says, on a sill pan, and trim it out inside.
Read morePage reviewed September 24, 2026 · JMB Builders LLC, MN license BC809005 · All install what you bought pages
Where we work
Install what you bought near you
Based in Zimmerman, scheduling across the Twin Cities metro. Closest first: