The questions that matter most when vetting a commercial window installer are about documentation, certification and scope boundaries, not about price per opening. A glazing contractor who can produce submittals, name the standards they install to, and tell you exactly where their scope ends is a different proposition from one who quotes a number and figures out the rest later.
These are the nine we would want asked of us, in the order they tend to matter on a commercial job.
1. Which installation standards do you work to?
Ask for standards by name, because the industry has them. The Fenestration and Glazing Industry Alliance publishes the AAMA and IGMA standards and runs the InstallationMasters installer certification program, currently at version 3.0.
Specific documents come up constantly on commercial work. FMA/AAMA 400 is the standard practice for installing exterior doors in surface barrier masonry construction for extreme wind and water exposure. AAMA/WDMA 100 is a standard practice for window installation. FGIA also publishes test methods for evaluating the performance of newly installed storefronts, curtain walls and sloped glazing systems, which means post-installation performance can be tested rather than argued about.
An installer who cannot name a single standard is telling you something.
2. Are your installers certified, and by whom?
Certification should attach to the crew doing your work, not to the company letterhead. Ask whether the people on site hold current certification and whether any of it is manufacturer specific.
Manufacturer certification matters more on commercial systems than most people expect, because warranty coverage on architectural glazing frequently depends on the system being installed by someone the manufacturer recognizes.
3. Can you produce submittals and shop drawings?
On any project with an architect or a general contractor, submittals are not optional, and a glazing sub who cannot generate them will slow the whole job. Ask to see a submittal package from a comparable project.
This is a reasonable proxy for whether a contractor has actually run commercial work. Residential window companies moving into commercial often cannot produce one.
4. Which systems do you actually install?
Storefront, curtain wall and punched openings are different systems with different detailing, and a contractor who installs one is not automatically competent at the others. Ask specifically.
We work with Tubelite, US Aluminum and Oldcastle BuildingEnvelope on the commercial side, and with Pella, Marvin, Andersen, Western Window Systems and Panda on architectural and residential work. Knowing which manufacturers a contractor has a real relationship with tells you what they can get, how fast, and whose technical support they can call when a detail is unusual.
5. Who is responsible for the waterproofing detail?
This is the question that prevents the most expensive argument on the project. Water intrusion at a window almost always originates at the interface between the window and the wall assembly, and that interface is frequently where one trade's scope ends and another's begins.
Get it in writing. Ask who flashes the opening, who ties the window into the air and water barrier, and who is on the hook if it leaks in year two.
6. Do you hold the permits, and do you know the local process?
In Austin, commercial window and door replacements fall under an Exterior Updates permit, which the City describes as covering updates that do not increase a building's size or raise its height by more than six feet. A contractor who works here regularly will know that without looking it up.
Ask who pulls the permit and who schedules inspections. On occupied commercial buildings, the inspection schedule frequently drives the work schedule.
7. Are your equipment operators certified for the lift you will need?
Upper-floor glazing means lifts, and lifts mean certified operators. Ask what equipment the job requires and who on the crew is certified to run it.
This is also a sequencing question. Equipment on site changes site access, parking and sometimes tenant operations, and a contractor who has thought about it will raise those before you do.
8. How will you work around an occupied building?
Commercial replacement rarely happens in an empty building, so ask directly how they phase work, secure openings overnight, and contain dust and debris. An opening that cannot be closed at the end of the day is a security and weather exposure.
9. What does your warranty actually cover, and who honors it?
Separate the product warranty from the labor warranty, because they come from different parties and frequently have different terms. Ask how long the installation is warranted, what voids it, and whether the manufacturer's coverage depends on certified installation.
Bringing it together
The pattern across all nine is the same: a commercial glazing contractor worth hiring can answer procedural questions without hedging, and one who cannot will cost you in change orders, inspection delays and eventually in water.
Tier One Custom Windows handles both residential and commercial work from Austin, with 30-plus years of combined team experience, and we also carry the trades around the opening, including reframing, masonry and finish work, which removes one of the scope-boundary arguments entirely. If you are vetting glazing subs for a Central Texas project, we are happy to be asked all nine. Call (512) 615-8629, or see how we work with general contractors and trade partners.