Pick the window contractor, not the window brand. Most window problems people live with, drafts, leaks, sashes that drag, frost on the trim, are installation problems. Verify the license on the Minnesota DLI site, ask for insurance, and get a quote you can compare line by line, including how the gap around each window gets insulated and sealed.
This applies to any Twin Cities homeowner hiring a full-service window company, and to anyone hiring labor-only to install windows they bought. The checks are the same, including for us.
How do you verify a window contractor's license in Minnesota?
Minnesota requires residential building contractors and remodelers to be licensed through the Department of Labor and Industry when they contract for work in more than one skill area, and a window job, with its tear-out, exterior finish and interior trim, almost always is. Ask for the license number and look it up on the DLI license lookup, where you can also see complaint and enforcement history. A license means the contractor carries required insurance, has passed the exams, and your project is backed by the state's Contractor Recovery Fund if things go badly. An unlicensed handyman window install forfeits those protections.
Why do insurance and workers' comp matter to you?
Ask for certificates of general liability insurance and workers' compensation. If an uninsured worker is hurt on your property, you can be exposed. A legitimate contractor hands over the certificates without hesitation. Hesitation is your answer.
What does a window quote you can compare look like?
A written quote worth comparing states, per opening:
- Window brand, series, frame material and glass package, with the NFRC U-factor and SHGC.
- Insert or full-frame scope, stated for each window.
- Interior and exterior trim, the insulation and sealing method, and how the opening is flashed.
- Rot repair pricing or a stated contingency rate.
- Haul-away, cleanup, timeline and payment schedule.
- The manufacturer's warranty and the contractor's own labor coverage, both in writing.
What should the quote say about insulation and sealing?
Two quotes for the same house can name the same window and deliver very different results, because the window is only half the job. Here is what to look for and what to ask, and the answers a real installer gives without thinking.
| Item | What a good quote says | What a weak quote says |
|---|---|---|
| Glass package | Low-E coating (and which surface), argon or krypton fill, double or triple pane, warm-edge spacer, NFRC U-factor listed | "Energy-efficient glass" with no numbers |
| Rating | U-factor 0.22 or lower meets ENERGY STAR Version 7.0 for Minnesota's Northern zone; 0.27–0.30 for a standard double-pane low-E argon unit; air leakage figure named | "ENERGY STAR" with no version or U-factor |
| Frame | Multi-chamber or foam-filled vinyl, fiberglass or wood-clad; compression weatherstrip on casements | Frame material not stated |
| Flashing | Sill pan under every unit, flashing tape shingle-lapped at sill, jambs and head, drip cap or head flashing on full-frame | "Caulked and sealed" |
| Frame gap | Low-expansion foam front to back, backer rod and sealant on the interior edge, exterior sealant with weeps left open | Not mentioned, or "insulated" with no method |
Which red flags should end the conversation?
The window industry has a high-pressure sales wing, and its moves are easy to spot: a today-only price that expires when the salesperson leaves your kitchen, an opening number that drops 40% after a call to the manager, a three-hour in-home presentation, and a large deposit demanded before anything is measured. None of that is how installers work.
Be wary of a quote well below the pack, too. The money usually comes out of installation labor, the part of the project you cannot see, and the foam and flashing are the first things dropped when a crew is paid by the window.
What questions reveal a real window installer?
Ask: who installs, employees or subcontractors, and who supervises? How do you insulate and seal the frame gap? Do you set a sill pan? What do you do when you find rot? Can I see recent local work? Confident, specific answers mean a company that installs for a living. Then send three photos of each window and see whether you hear back within one business day with every opening itemized.
What JMB Builders does
JMB Builders is a licensed Minnesota residential building contractor (BC809005) based in Zimmerman, working across the Twin Cities metro. One crew does the measuring, the install and the trim, we install every brand and sell none, and every question above gets a straight answer. Paid by check or direct deposit. Call 763-204-2099 (text) or send photos through the site.
- Full-service window and door replacement, measured and ordered by us — jmbbuildersmn.com/services/full-service
- Labor-only installs of windows and doors you bought at a store or online — jmbbuildersmn.com/services/labor-only
- Which window brand to buy when you are hiring the install separately — jmbbuildersmn.com/services/labor-only/which-window-brand-to-buy-for-labor-only-install
- Trim-out after the windows go in: jamb extensions, casing, stool and apron — jmbbuildersmn.com/services/window-trim
- Send three photos and we reply within one business day.
Frequently asked questions
How do I check if a window contractor is licensed in Minnesota?
Ask for the license number and look it up on the Minnesota Department of Labor and Industry license lookup. The record shows whether the license is active and any complaint or enforcement history. An installer working under a handyman name with no license number is not covered by the state's Contractor Recovery Fund.
Does a window installer need a license in Minnesota?
In nearly every case, yes. Minnesota requires a residential building contractor or remodeler license from DLI for anyone contracting to do work in more than one skill area, and a window replacement with tear-out, exterior finish and interior trim qualifies. The license is what puts required insurance and the Contractor Recovery Fund behind your project. Ask for the number before you sign anything.
How many window quotes should I get?
Three is plenty. Make each one itemize per opening and name the same things: brand and series, glass package with U-factor, insert or full-frame, flashing and frame-gap sealing method, trim inside and out, and haul-away. Then compare the specification, not the bottom line. A 2x spread on the same house is common.
Is a cheap window quote a red flag?
A quote well below the others usually takes the money out of installation labor, the part you cannot see. Check whether trim, disposal, rot repair, a sill pan and frame-gap foam and sealing are in the number. If they are not, they come back later as change orders or as drafts.
Should I let a window salesperson into my house?
Not for a three-hour presentation. A quote from photos or a short measure visit tells a good contractor what they need. Today-only prices, a call to the manager for a discount, and a large deposit before measuring are sales tactics, not how installers work.
Who actually installs the windows, the company or subcontractors?
Ask. Many window companies sell the job and hand it to subcontractors paid per window, which is where speed beats care and the foam and flashing get skipped. Find out who will be on your job, who supervises, and who you call when something is wrong afterward.
