Scope, bid documents, proposals, insurance, submittals, coordination and close-out for the window trade.
For a general contractor, the window subcontractor is one of the trades that closes the building. Until the windows are in, the interior trades cannot start in earnest; if they leak, everyone comes back. This article is written for GCs and construction managers hiring a window subcontractor in NYC: what the scope should cover, what to ask for at bid, and how a good sub runs the work.
The cleanest scope gives one subcontractor the whole opening, from the rough opening inward:
Where the flashing or sealant belongs to another trade, the boundary should be drawn on a detail and signed by both. Most window leaks are scope gaps.
The more complete the bid package, the fewer exclusions come back in the proposals.
Level the bids before comparing totals. Check each proposal for:
Ask every bidder for a current certificate of insurance showing general liability, workers’ compensation and any umbrella coverage the project requires, with the owner and contractor named as required by the contract. Ask who will supervise on site and what safety training the crew holds; New York City sites require site safety training for workers on most larger projects. A subcontractor who cannot produce these quickly at bid will not produce submittals quickly either.
After award, the sub issues shop drawings, product data, finish samples and test reports. Fabrication cannot start until they are approved, so the GC’s role is to keep the design team’s review moving. Agree a turnaround time for each round of review at the kickoff meeting. A two-week delay in approvals becomes a two-week delay in windows, and usually more.
A short weekly coordination meeting during the facade phase is worth more than any clause in the subcontract.
Ask the sub how many installers the job will have and how many openings a day they expect to complete once the first floor is done. Then check it against the dates. Production always starts slowly: the first floor proves the details and gets tested. A realistic schedule shows that ramp.
We take window, storefront, curtain wall and interior glass scopes as a subcontractor to general contractors and construction managers across the city, and we carry insurance for that work. On 3915 Flatlands Avenue the scope was the complete glazing of a new office building; on 99 Claremont Avenue it was the windows on an occupied institutional building, working under the general contractor. We can also price supply-only for contractors with their own installers.
Require a mock-up in the subcontract: the first typical window installed complete with sill pan, flashing and sealant, reviewed by the architect and water tested before production continues. Then test a sample on each elevation as the work proceeds. Agree in advance who pays for the testing agency and who pays for retests after a failure. Subcontractors who are confident in their details welcome this; it protects them as much as the GC.
Some GCs buy the windows directly and hire a sub for labor only. It can lower the headline cost, but the GC then owns the dimensions, the delivery schedule and any shortage or damage, and a leak becomes an argument between two contracts. A supply-and-install subcontract costs a little more and gives one point of responsibility. If you do buy direct, have the installing sub review the shop drawings and attend the first delivery.
Window subcontracts carry a large material cost before any work is visible on site, because fabrication deposits are paid months ahead. A schedule of values that recognizes approved shop drawings, materials fabricated and stored, delivery and installation separately keeps the sub financed and the job moving. Agree how stored materials are documented and insured.
Supplies and installs the windows and related glazing: shop drawings, field measurement, delivery, installation, flashing and sealant at the frame, testing and close-out.
The proposed system and its test reports, glass make-ups, inclusions and exclusions, lead time, a certificate of insurance and references for similar buildings.
It depends on the subcontract. Giving the window subcontractor the sill pan, frame flashing and perimeter sealant puts one party in charge of the opening.
As early as the drawings allow, usually during foundations or early structure, because approvals and fabrication take months.
Yes. We take window, storefront, curtain wall and interior glass scopes under general contractors, and also supply materials only.
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About this page. Written by Alex GC Inc. d/b/a Alex Glass Construction and reviewed before publication by Aleksandr Chernovolenko, Managing Partner, with our design and estimating lead and a field foreman. Our foremen hold the NYC DOB Site Safety Training supervisor card and our crews the 40-hour worker card; we are certified to fabricate, install and service Alutech and Everest aluminum systems. Facts are drawn from our own projects, manufacturer test data and the applicable codes; where we are giving an opinion, we say so. Last reviewed September 2026. Credentials
Send the window schedule, elevations or a simple list of sizes and quantities. We will price it, with or without installation, and confirm the lead time.
