Windows specification checklist
A practical checklist for specifying windows: frame material, glazing, ratings, installation, hardware, documents and lead time, without guessing at performance.
A window specification is a list of decisions: what type of window, what performance, how it is installed, and what proof you need. Writing it down before asking for quotes avoids unlike comparisons and surprise substitutions. Use this page as a checklist for conversation with the designer and suppliers, and replace the placeholders with your project requirements.
Type, size and operation
- Operation: fixed, casement, awning, double hung, sliding, tilt-turn, or other.
- Overall size, rough opening size and tolerance, and the sill and head details.
- Egress requirements for sleeping rooms, set by local code (confirm locally).
- Number of units by type, with a window schedule keyed to the drawings.
- Screens, grilles, between-glass bars, and exterior or interior color.
Order from a schedule with measured rough openings, not from plan dimensions. Confirm by site measurement before manufacturing begins.
Frame and glazing
| Choice | What to compare |
|---|---|
| Frame material (vinyl, aluminum, wood, clad wood, fiberglass, steel) | Thermal break, durability, maintenance, finish, sightlines |
| Glazing (single, double, triple) | Gas fill, coating, spacer type, thickness |
| Safety glazing | Where tempered or laminated glass is required by code |
| Spacer and seal | Edge seal warranty, condensation risk at edges |
| Coatings and tints | Visible transmittance, solar control, appearance |
Ask for the whole-window values, not center-of-glass values only. Center-of-glass figures look better than whole-window figures and are not what energy rules use.
Ratings and standards to specify
North American windows are commonly rated for thermal performance through NFRC, and ENERGY STAR sets program criteria that vary by climate zone. For structure and weather, performance is often described through the North American Fenestration Standard (NAFS), which covers design pressure, water penetration and air leakage classes. Request the rating label or certification listing number and verify it on the program site. Do not accept a verbal claim.
If you are outside North America, replace these with the local standards and ask the supplier which they hold. Coastal and high-wind areas often need additional impact or pressure requirements that the designer sets.
Hardware, finishes and security
Hardware affects daily use and maintenance: locks, hinges, balances, operators. Ask what is a standard part and what is proprietary, because replacement parts for obscure hardware can be hard to obtain. For finishes, ask about warranty on color, chalking or fading, and cleaning guidance. For security, check lock points and glazing method.
Installation and flashing
Specify the installation method: nailing fin, installation clips or masonry opening. Require a sill pan or sloped sill flashing, head flashing, sealed perimeter, and low-expansion foam or backer and sealant, per the manufacturer instructions. The flashing guide and sealants checklist support this.
Check that the window maker and the wall barrier maker approve the same tape and sealant at the interface.
Documents, lead time and delivery
- Shop drawings with sections and fastening information.
- Test and rating reports or certificate numbers.
- Warranty terms for frame, glass, hardware and seals.
- Delivery schedule with a confirmed production slot.
- Protection plan: labels, film, packaging, storage.
- Sample or mockup window for the first unit installed.
Lead times vary by manufacturer and finish, so ask for the date in writing and what could change it. Inspect on delivery for glass damage, bent frames, and correct sizes before signing. This page is general education; performance targets and code compliance belong to the designer and the local authority.
Questions to ask a window supplier
- Which rating labels and listing numbers apply to each window type in this order?
- What is the production lead time, and what pauses it?
- Are glass, spacers and seals covered by warranty, and for how long?
- What are the tolerances on size and squareness?
- Do you provide installation instructions that match our wall and flashing detail?
- Can you supply a sample corner section and a hardware sample?
Compare answers side by side in a simple grid so differences are visible. A weighted matrix works well when the team has to agree on a supplier.
Questions people ask
What should a window specification include?
Type and operation, frame material, glazing makeup, performance ratings required, size and tolerances, hardware, finish, installation and flashing method, documents, and lead time.
What do U-factor and SHGC mean?
U-factor measures heat transfer through the window; SHGC (solar heat gain coefficient) measures solar heat admitted. NFRC runs the rating system used in North America.
Do I need tested structural ratings?
Often yes. Design pressure and water resistance ratings come from tests under the product standards the local code cites. Confirm requirements with the local authority.
Why does installation matter so much?
Even a good window leaks or loses performance if flashing, sealant and air sealing are wrong. Follow the maker and the project details.
Sources and further reading
Have a project outline or drawings?
Organize your scope, then contact Digital Oro through its official channel. Availability, engineering, pricing and delivery terms need project-specific confirmation.
Explore Digital Oro →Digital Oro International advertises on The Company Chronicle. This guide was written by our editorial team from public sources and general professional practice; it does not describe a guarantee, quote or offer from Digital Oro International. Confirm current terms, prices and availability with the operator before you decide.