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Contact us today to get started with a free quote!
Contact us today to get started with a free quote!
Fiberglass sits between vinyl and wood. It's stronger and more stable than vinyl, holds dark colors without fading, and never needs the care wood does. The fiberglass windows we install are from Marvin's Essential collection, built from Marvin's Ultrex fiberglass inside and out. Zags Exteriors is an authorized Marvin dealer, so we order, install, and stand behind them directly.
We install fiberglass windows for homeowners throughout Chicagoland, and for HOA, condo, and large residential projects in Central Illinois and St. Louis.
Most of what sets fiberglass apart comes down to how it handles heat, cold, and time.
It moves with the glass. Every window frame expands in summer and shrinks in winter. When the frame moves more than the glass, the seals get worked loose over the years, which is where drafts and foggy glass come from. Marvin's Ultrex fiberglass expands and contracts at nearly the same rate as glass, with 87% less expansion than vinyl by Marvin's testing, so the window stays tight through Chicago's temperature swings.
It's strong. Marvin rates Ultrex as eight times stronger than vinyl. That strength lets the frames be thinner, so you get more glass and a bigger view from the same opening, and it keeps sashes square and operating smoothly for years.
It holds dark colors. Black and bronze windows are popular, and dark finishes are hard on any material that softens in the sun. Ultrex is heat resistant, and its acrylic finish is three times thicker than typical painted finishes, so it resists fading, chalking, and peeling even in the darkest colors.
It's virtually maintenance free. No painting, no staining, no sealing. The finish is the same inside and out, so a rinse now and then is all it needs.
Fiberglass is usually the right call when one of these matters to you:
If none of those stand out, a good vinyl window will serve most homes well. See vinyl replacement windows. If you want real wood inside, Marvin’s Elevate collection pairs a wood interior with the same Ultrex fiberglass exterior. See wood windows.
| Vinyl | Fiberglass | Wood | |
|---|---|---|---|
| Interior | White or wood grain look | Painted finish, white or dark | Real wood, stained or painted |
| Exterior | Vinyl, many colors | Fiberglass, 6 colors | Aluminum clad, fiberglass, or wood |
| Maintenance | None | None | Interior wood needs care |
| Strength and stability | Good | Best | Very good |
| Dark colors | Available | Best for dark colors | Available |
| Best for | Most homes | Dark colors, big glass, long term durability | Historic homes, real wood inside |
We’ll price any of the three on your estimate so the choice comes down to real numbers on your house.
Marvin Essential comes in every common window style:
Outside, choose from six colors: Stone White, Cashmere, Pebble Gray, Bronze, Gunmetal, and Ebony. Inside, Stone White goes with any exterior, or you can match a Bronze, Gunmetal, or Ebony exterior on the inside too for a fully dark window. Grilles between the glass are available in popular patterns, and divided lites are available on select products.
Every Essential window has dual pane glass with a Low E coating and argon gas between the panes, with Low E options tuned for northern climates. Specialty glass is available for sound control, privacy, and safety.
Energy performance depends on the exact window, size, and glass you choose, so we don’t quote one number for every window. We’ll give you the whole window U-factor from the NFRC label for each window on your estimate, and if ENERGY STAR certification matters to you, we’ll confirm it for the exact configuration we’re quoting.
Every window project starts with a design consultation. Before we talk products, we look at the house as a whole: its age and architecture, the trim, the siding and roof colors, and the windows you're keeping. From there we'll recommend the styles that suit each opening, the exterior and interior colors that work with the rest of the house, and grille patterns that match its period.
Dark windows in particular change how a house reads from the street, so we'll help you decide where black or bronze looks sharp and where white or a softer neutral fits better. If an HOA or review board has standards for exterior changes, we'll design to those from the start. We bring samples so you're deciding in front of your house, not off a screen.
A good window installed badly leaks air and water like a bad one. Most of what makes a replacement window perform happens in the hour around the window, not in the window itself.
Insert or full frame, depending on what we find. We do both. Essential double hung and single hung windows come in insert versions that fit inside your existing frame, which keeps your interior and exterior trim in place and goes faster. It's the right call when the old frame is solid and square. A full frame install takes the window out down to the rough opening. That's what we recommend when the frame is rotted, the opening is out of square, or you want to change the size or style of the window. We'll tell you which one each window needs after we've seen it, and on a lot of houses it's a mix.
Measure, then order to fit. Every window is built to order, so we measure each opening ourselves rather than going off the old window's size.
Check what's under the old window. With the old window out, we look at the sill and framing for rot and water damage, and we'd rather fix it than cover it.
Insulate, flash, and seal. The gap between the new window and the opening gets insulated, and the exterior gets flashed and sealed so water sheds away from the window instead of into the wall.
Finish and cleanup. We finish the interior trim, haul away the old windows, and clean up before we leave.
Because we're an authorized Marvin dealer, your windows and doors carry Marvin's full limited warranty, and it transfers to the next owner if you sell. It covers the insulating glass seal for 20 years on most window sizes and the window's materials and workmanship for 10 years. Every Zags installation is also backed by our own five year labor warranty. We'll walk you through exactly what each one covers before any work starts.
In strength, stability, and how well they hold dark colors, yes. Marvin rates its Ultrex fiberglass as eight times stronger than vinyl, and it expands and contracts far less with temperature changes, which helps the seals last. A good vinyl window still performs well on most homes, so it comes down to what matters most on your house.
Yes. Marvin Essential comes in Ebony, Gunmetal, and Bronze outside, and you can match the inside to the same color for a fully dark window. Ultrex fiberglass and its finish are built to resist fading and chalking even in dark colors.
Almost none. There’s nothing to paint, stain, or seal. Rinse the frames and clean the glass now and then.
Fiberglass is one of the longest lasting window materials because it doesn’t warp, rot, or break down in sunlight. How long any window lasts also depends on how well it’s installed, which is why we flash and seal every opening.
Yes. Marvin’s Elevate collection pairs a real wood interior with an Ultrex fiberglass exterior. See our wood windows page.
Often, yes. Essential double hung and single hung windows come in insert versions that fit inside your existing frame, so the trim stays. If the old frame is rotted or out of square, a full frame replacement is the better choice.
Yes. Marvin Essential includes a sliding patio door in the same fiberglass and colors as the windows.
Yes. Zags Exteriors is an authorized Marvin dealer, so we order Marvin windows and doors directly, install them, and your project carries Marvin’s full warranty.
Marvin’s limited warranty transfers if you sell. It covers the glass seal for 20 years on most sizes and the window’s materials and workmanship for 10 years. Our installation is covered by a five year labor warranty.
Yes, we offer financing on window replacement projects.
