GlasFëns
Information
The technical library — building science, standards, and specification detail, written plainly. Every performance claim is labeled by how it was established.
Window & Door Types
How each window and door opens, in plain language: tilt & turn, casement, awning, lift & slide, and more.
Size Limits
Minimum and maximum sash sizes and weight capacity by opening method.
Material Choices
Fiberglass, aluminum, wood and vinyl compared, and why our polyurethane fiberglass insulates better than vinyl and wood.
Daylighting
Designing new buildings for natural daylight: window height and depth, glass by elevation, controls and daylight metrics.
Air Infiltration
How window air leakage is tested, what codes and Passive House require, and how to estimate its energy cost.
Ratings, Codes & Certifications
Which codes, ratings and certifications apply to windows, and how they fit together.
NFRC & ENERGY STAR
What the NFRC label measures, how products are rated, and the ENERGY STAR criteria.
LEED
How windows contribute to LEED v4.1 and LEED v5.
Passive House & Phius
The two Passive House standards, how they differ, and what each asks of a window.
Which Rating Applies?
NFRC, Phius, PHI and CSA compared for houses, multifamily and commercial buildings in the U.S. and Canada.
Energy Codes, U.S. & Canada
How energy codes are adopted and enforced, where they are strict or absent, and where they are heading.
Codes by State, Province & City
What applies in key U.S. states and cities, Toronto, Montréal and Vancouver.
Structural & Weather Ratings
NAFS wind, water and air testing, and hurricane, coastal and tornado requirements.
U-Value & SHGC
What U-factor, R-value, SHGC and VT mean, and how the frame and the glass change them.
Thermal Performance
How heat moves through windows, how it is rated, how to read claims, and what frame, edge, glass and installation contribute.
Condensation Resistance
Why windows fog, how condensation resistance is rated in the U.S. and Canada, and how to choose windows that stay dry.
Air Barrier Interface
Connecting windows to air, vapor and water barriers on wood, steel, concrete and masonry, with tapes, membranes and sealants.
Glass and Glazing
Technical reference.
Installation
Our recommended installation: window position, direct set vs fins and clips, sealing and adjustment.
Terms & Conditions
GENERAL TERMS AND CONDITIONS (REV. 02192020)
Warranty
BUYER’S FAILURE TO PAY ALL SUMS DUE IN STRICT ACCORDANCE WITH GF TERMS AND CONDITIONS/QUOTE WILL VOID APPLICABLE WARRANT
Resources
Our technical guides, plus standards bodies, codes, approvals and Passive House programs.
Key to NFRC Codes
How to read NFRC product listings: every product, frame, glass, gas, spacer and grid code.
Affiliations
CLICK LINKS BELOW FOR FURTHER INFORMATION.
Glossary
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
Frame Width Comparisons
Interior frame-width sections compared at the same scale.