Specifications & Testing Data
| Frame material | Wood interior, extruded aluminum-clad exterior |
|---|---|
| U-factor (NFRC) | 0.25 – 0.3 |
| Solar heat gain coefficient (NFRC) | 0.22 – 0.33 |
| Design pressure (DP) rating | Engineered per unit; large and mulled configurations carry certified ratings |
| AAMA performance class | AAMA 2605 exterior finish available (architectural grade) |
| ENERGY STAR zones | Northern, North-Central |
| Glass options | Dual-pane Low-E w/ argon, Triple-pane, Tempered, Laminated/sound control, Decorative & divided lite |
| Available styles | Casement, Double-Hung (Sterling), Awning, Glider, Picture, Radius & specialty shapes, Custom sizes |
The Customization House
Kolbe has built windows in Wausau, Wisconsin since 1946, and its identity in the premium market is specific: the manufacturer that says yes. Odd sizes, true radius heads, deep custom colors, divided-lite patterns matched to a 1912 original — the Ultra Series is the clad-wood line architects reach for when the catalog answer isn't the design answer.
Construction is classic premium clad-wood: solid wood interiors ready for stain or paint, extruded aluminum cladding outside (extruded, not rolled — noticeably thicker and stiffer), with architectural-grade finishes available for dark and custom colors.
The Numbers
NFRC-certified U-factors on common Ultra configurations run 0.25–0.30 with dual-pane Low-E and argon, with triple-pane options pushing into the mid-0.20s for cold-focused builds. SHGC tunes by glass package from 0.22 to 0.33 — enough range to treat a southwest view wall and a shaded north bedroom as the different problems they are. Large, mulled, and specialty units carry per-unit engineered design pressure ratings, which is what lets us specify them on exposed foothills elevations with a straight face.
Where Kolbe Wins in the Valley
Historic and character work. Boise's North End, East End, and Hyde Park districts want profiles and proportions that belong to the house. The Ultra's custom sizing and authentic divided lites are how we deliver that with modern glass inside — it's the line we quote when design review is part of the project.
The design that doesn't fit the catalog. Radius windows over an entry, a mulled bank sized to the sixteenth of an inch, interior wood species matched to existing trim. Kolbe's tolerance for "custom" is the widest we carry.
Dark, architectural exteriors. Extruded cladding in AAMA 2605-class finishes holds deep colors through decades of high-desert sun.
Where we point you elsewhere: standard whole-house replacements. If nothing about the project demands customization, the Andersen 400 Series or Marvin Elevate deliver premium performance for meaningfully less, and we'll show you those numbers in the same quote.
Dealer-Backed, Locally Installed
Kolbe's limited warranty (20-year insulated glass, 10-year on most components) is serviced through us — the authorized dealer that measured, ordered, and installed the units with our own employee carpenters. Custom work rewards installers who sweat the details; that's been our trade since 1980.
Bring us the drawings, or just the idea: (208) 376-2200 or the form on this page.
Frequently Asked Questions
Where does Kolbe fit against Marvin and Andersen?
Same premium clad-wood tier as Marvin Ultimate and Andersen's architectural lines, with a reputation built on customization — unusual sizes, radius and specialty shapes, deep divided-lite and finish options. When a design calls for something the big two's catalogs don't quite cover, Kolbe is usually where we find it. We're authorized dealers for all three, so the comparison is real, not rhetorical.
Is the Kolbe Ultra Series good for historic homes?
It's one of our go-to answers for them. The Ultra's wood interiors, authentic divided lites, custom sizing, and traditional profile options let us match century-old character in Boise's historic districts while hiding modern Low-E performance inside — the combination design review committees want to see.
What does the Kolbe Ultra Series cost?
Premium clad-wood pricing: most installed configurations run $1,500–$2,800+ per opening in the Treasure Valley depending on size, shape, glass, and finish. Radius work and custom shapes price individually. Firm numbers come from a free in-home measure with drawings if you have them.
How does the Ultra Series handle Idaho's climate long-term?
The construction is proven for it: a wood core insulating against winter cold, wrapped in extruded aluminum — thicker and stiffer than rolled cladding — finished to architectural coating standards. With NFRC U-factors from 0.25 to 0.30 and per-unit design pressure ratings, it's specified confidently from North End restorations to exposed foothills builds.
Sources & Testing Data
Last reviewed 2026-07-04 by Wood Windows Inc — (208) 376-2200