Andersen 100 Series: Specs, Testing Data & Idaho Fit

Specifications & Testing Data

What the 100 Series Actually Is

Let's get the headline out of the way: the Andersen 100 Series is the window Wood Windows Inc sells more of than anything else — more than any Marvin, Milgard, or even Andersen's own 400 Series. After 46 years of putting windows into Treasure Valley homes, that is not a small statement, and it comes down to the material.

The 100 Series is built entirely from Fibrex, Andersen's proprietary composite. By weight it is about 40% wood fiber — mostly reclaimed sawdust from Andersen's own wood-window plants — locked inside 60% thermoplastic polymer. Every wood cell is filled and encased, so the material takes the strength and thermal stability of wood without the rot, and the low maintenance of vinyl without the softness. Andersen's published claim is twice the strength of vinyl; the practical result is a frame that stays rigid under a sash, holds a weathertight seal, and does not creep in heat.

In Andersen's lineup the 100 Series sits at the entry point, below the 200 Series and 400 Series (both wood core with vinyl cladding) and well below the A-Series and E-Series architectural lines. Do not read "entry" as "builder grade." Read it as the line Andersen designed to beat vinyl at vinyl's own game.

The Numbers That Matter

Andersen publishes NFRC total-unit ratings by product type and glass package, and the 100 Series data (2024-25 guide, revised October 2025) is worth reading closely:

Values are U-factor / SHGC, no grilles. Full-divided-light grilles add roughly 0.01–0.02 to U-factor.

Two takeaways. First, HeatLock — a room-side coating that reflects heat back into the house — is the single biggest lever on this line, worth 0.04 of U-factor for a small upcharge. We order it on nearly every 100 Series job in Idaho. Second, ENERGY STAR Version 7.0 moved the Northern-zone U-factor line down to 0.22, so standard dual-pane 100 Series units certify in the North-Central zone but not Northern. Andersen has since added an "Enhanced" Low-E package to the casement and picture tables that tests as low as 0.15–0.19; availability and lead time in our market vary, so ask us before you count on it.

Structurally, the single-hung is Hallmark certified to Class LC-PG30 (DP +30/-30) at a tested size of 143.5 by 71.5 inches — a very wide test unit, which means typical residential sizes have headroom. Air infiltration meets the 0.2 CFM/sq ft code ceiling. Exterior colors run to five, including Black and Dark Bronze; interiors come in four.

One gap worth naming: the double-hung described below is not yet in Andersen's published 100 Series performance guide (its data is dated August 2023, before the double-hung existed). It uses the same Fibrex frame and the same glass packages as the single-hung, so we expect the numbers to land close to that row, but we will not print a figure Andersen has not certified. Every unit ships with its own NFRC label, and that label is what goes in your quote.

The Double-Hung: New to the Line, Now Orderable in Idaho

For most of its life the 100 Series had one vertical-sliding window, the single-hung, where only the bottom sash moves. If a homeowner wanted a true double-hung under the 400 Series price, we had to move them to the wood-interior 200 Series. Andersen closed that gap in 2025 with a 100 Series double-hung, first in a couple dozen eastern and midwestern states and, as of 2026, orderable through us for Treasure Valley jobs.

What you get is the standard double-hung promise built in Fibrex: two operating sashes for top-and-bottom ventilation, both of which tilt in so you wash the exterior glass from inside the room. That is the feature people upgrading from 1990s sliders and single-hungs ask for most, and it matters on second-story bedrooms where nobody wants to be on a ladder. Sightlines and frame depth match the rest of the 100 Series, so a double-hung in the front bedroom and a single-hung in the garage look like one family from the street.

Source: Andersen 100 Series Double-Hung Specification Guide, revised October 2025, and the January 2025 product info sheet, both linked below.

Two practical notes from the spec guide. First, the cottage and reverse-cottage sash ratios are a real design tool: a 2:3 cottage sash puts the meeting rail above eye level in a living room, which is how older Boise bungalows were built, and it is not an option the single-hung offers. Second, tempered glass can limit sash travel on this unit, so on stair landings and tub surrounds where code calls for tempering, we check the clear opening against egress before we order.

Where it fits: replacement work on traditional-style homes where the owner wants the double-hung look and the tilt-in cleaning but is not staining interiors. Where it does not: if you want a stained pine interior on your double-hung, that is still the 200 or 400 Series conversation, and the casement vs. double-hung trade-offs on sealing and wind exposure apply here exactly as they do to any double-hung.

Where It Fits in Idaho — and Where It Doesn't

The 100 Series is the default window in new Treasure Valley subdivisions for good reason: a black or dark bronze exterior with a white interior is the look production builders and their buyers want, and vinyl cannot deliver dark exteriors without warranty headaches. On replacement work it shines in the 1990s–2010s housing stock across the valley, where original vinyl or aluminum sliders are failing and the homeowner wants a visible upgrade without a custom-window budget. HOAs that prohibit "vinyl windows" on street-facing elevations generally accept Fibrex, which has settled more than one architectural-review argument for us.

Where we steer people elsewhere: if you want stained wood interiors, this is not your window — go to the 400 Series. Historic North End and East End homes under design review usually need the deeper profiles of clad-wood. Very large fixed glass and unusual shapes push past the 100 Series size chart into the A-Series or E-Series. And on a strict budget for a rental or a flip, a Milgard vinyl unit hits code with less money out the door, and we will quote it alongside the 100 Series without a sales pitch.

Warranty and Service, Locally

Andersen backs the 100 Series with its Owner-to-Owner limited warranty — 20 years on glass, 10 years on non-glass components, 10 years on the Fibrex exterior finish — and it transfers to the next owner for whatever is left of each term. Fibrex itself carries Andersen's written promise that it will not flake, blister, peel, or corrode, and that is borne out by the oldest Fibrex units we service, which look the way they did on delivery day. Because we are an authorized Andersen dealer, Andersen also covers the labor on warranty repairs for the first two years after you buy from us, something a big-box purchase does not come with. We lay out exactly what is and is not covered in our line-by-line reading of the 100 Series warranty.

Warranty service on any Andersen product we sell is handled by Wood Windows employees working out of our Garden City shop, not a third-party service network. If a balance or a lock ever fails, the crew that installed your windows is the crew that comes back.

Want a line-by-line quote with the exact NFRC label values for your openings, or a side-by-side against the 400 Series or Milgard? Use the form on this page or call (208) 376-2200.

Last reviewed 2026-09-18 by Wood Windows Inc — (208) 376-2200