Specifications & Testing Data
| Frame material | Glastra — a fiberglass/polymer hybrid, full-frame or with wood interior option |
|---|---|
| U-factor (NFRC) | 0.26 – 0.3 |
| Solar heat gain coefficient (NFRC) | 0.23 – 0.33 |
| Design pressure (DP) rating | Commonly DP 40-class on standard sizes; verify per configuration |
| AAMA performance class | Certified to AAMA/NAMI standards; class varies by unit |
| ENERGY STAR zones | Northern, North-Central |
| Glass options | Dual-pane Low-E w/ argon, Tempered, Obscure, Divided lite options |
| Available styles | Casement, Awning, Double-Hung, Glider, Picture, Specialty shapes |
Kolbe's Answer to the Fiberglass Question
The Forgent Series is Kolbe's modern-materials line, built around Glastra — a fiberglass/polymer hybrid the company engineered for strength, UV stability, and cleaner profile lines than raw pultruded fiberglass typically allows. Positioned below the clad-wood Ultra Series, it competes squarely in the premium-fiberglass tier where we also quote Marvin Essential and Milgard Ultra.
The Numbers
Common Forgent configurations test at NFRC U-factors of 0.26–0.30 with dual-pane Low-E and argon — on target for zone 5B — with SHGC options from 0.23 to 0.33 for elevation-by-elevation solar tuning. Standard sizes commonly carry DP 40-class design pressure ratings, comfortable for open Treasure Valley exposure. Like every fiberglass-family frame, Glastra's low thermal expansion is the quiet advantage: the frame moves with its glass through Idaho's daily temperature swings instead of working the seal.
How It Slots Into a Quote
Three situations bring the Forgent out of our book. First, the all-Kolbe project — a custom home or remodel using Ultra Series where it shows, Forgent where practicality rules, one manufacturer, one aesthetic family. Second, the fiberglass shopper comparing brands — Forgent vs. Marvin Essential vs. Milgard Ultra is a genuinely close race we're happy to run honestly, since we carry all three. Third, dark-frame durability buyers — Glastra carries black and bronze safely on exposures where we'd counsel against vinyl.
Where it's not the answer: strict-budget whole-house jobs (quality vinyl wins the math) and historic-district profile matching (that's the Ultra Series' job, one shelf up).
Same Wausau Quality, Simpler Package
What carries over from Kolbe's premium heritage: dealer-network distribution, real options depth for the tier, and manufacturing quality control we've come to trust in years of installs. What's simplified: the endless custom range — Forgent sticks closer to standard sizes and popular configurations, which is exactly how it hits its price point.
Kolbe's limited warranty applies (20-year insulated glass; component terms by line), serviced locally by the Wood Windows employee crews who installed it — never subcontractors, since 1980.
Run the three-way fiberglass comparison for your home in one free measure: (208) 376-2200 or the form on this page.
Frequently Asked Questions
What exactly is Glastra?
Kolbe's hybrid frame material — fiberglass blended with a UV-stable polymer. The aim is fiberglass's strength and thermal stability with better moldability, so profiles come out cleaner than pure pultrusions. In the field it behaves like the other premium fiberglass frames we install: stiff, stable, and safe in dark colors.
Who is the Forgent for?
The buyer who wants Kolbe design quality without clad-wood pricing — the same customer we'd otherwise show a Marvin Essential or Milgard Ultra. It's also the budget-conscious path to keeping one manufacturer across a project that mixes Ultra Series showpieces with practical windows elsewhere.
How does Forgent price against other fiberglass windows?
Competitively within the premium-fiberglass tier: typically $950–$1,500 installed per window in the Treasure Valley, overlapping Marvin Essential and running above Milgard Ultra. We quote them side by side often — small differences in sightlines, hardware feel, and options usually decide it.
Does the Forgent come with a wood interior like the Elevate?
Select Forgent units offer a wood-interior option over the Glastra frame, giving a warmer room-side look without stepping up to the full Ultra Series. Availability depends on style and size — we confirm options at the measure.
Sources & Testing Data
Last reviewed 2026-07-04 by Wood Windows Inc — (208) 376-2200