Material Choices

FIBERGLASS

Fiberglass (pultruded fiberglass) is the highest performing frame material we offer and the heart of the GlasFëns line. It is made by pulling continuous glass fibers through a bath or injection of resin and curing them, in a heated die, into an incredibly strong, dimensionally stable composite. Because the frame is essentially the same material as the glass it holds, the two expand and contract together, so the whole window stays tight and true for decades. Fiberglass brings together the strength of aluminum, better insulating value than wood and the low maintenance of vinyl, without the drawbacks of any of them, which is why it is what we build our windows and doors around.

NOT ALL FIBERGLASS IS THE SAME

“Fiberglass” describes the glass fiber. What holds those fibers together, the resin, is what separates one fiberglass window from another. Most fiberglass windows are pultruded with polyester resin, because it is inexpensive and simple to run. Some use vinyl ester. Ours are pultruded with polyurethane resin from Huntsman Advanced Materials, part of Huntsman Corporation of The Woodlands, Texas.

Polyurethane is the premium resin for pultrusion. It costs more than polyester and takes more exacting equipment and process control on the pultrusion line, with metered two-part injection instead of an open resin bath. In return, it makes a better frame:

Sources: Huntsman RIMLINE® pultrusion data; Liberty Pultrusions; Design News; EN ISO 10077-2, Annex A. GlasFëns conductivity: independent laboratory test by Intertek.

THE BEST-INSULATING FRAME MATERIAL

Thermal conductivity, λ, measures how easily heat flows through a material: the lower the number, the better it insulates. Intertek, one of the world’s largest independent testing laboratories, measured our pultruded polyurethane fiberglass at 0.114 W/m·K. That is lower than rigid PVC, the material of vinyl windows, and lower than both softwood and hardwood.

All values except ours are design values from EN ISO 10077-2, Annex A, the international standard for calculating window frame heat loss.

Material conductivity is one input to how a frame performs; the profile design is the other. Our pultruded profiles are filled with polyurethane foam, so heat finds no open air path through the frame, and they need no steel reinforcement, which vinyl frames do. The Passive House Institute certified our GR85 frame at U_f 0.72 W/m²K while conservatively assuming a fiberglass conductivity of 0.27, more than twice the value Intertek measured, so the frame performs even better than its certificate states. See the performance data for every system.

ADVANTAGES OF FIBERGLASS:

● Made from the same silica base as glass, so the frame expands and contracts at nearly the same rate as the glass it holds, keeping seals and glazing tight with far fewer air and water leaks over the life of the window

● Extremely low thermal expansion and contraction, dimensionally stable through extreme heat, cold and rapid temperature swings, so it will not warp, twist or bow

● Insulates better than vinyl and wood: our polyurethane fiberglass measured λ 0.114 W/m·K, with no thermal break and no steel reinforcement needed

● Exceptionally strong and rigid, stronger than vinyl and wood and comparable to aluminum, allowing narrow sightlines and large spans for slim frames and maximum glass and daylight

● Will not rot, rust, corrode, swell, warp or peel, and is impervious to moisture and insects, ideal for coastal and humid climates

● Virtually maintenance free, yet it can be painted any color, and touched up on site if it is ever scratched, unlike vinyl

● Long service life measured in decades, and UV stable, so it will not fade, chalk or become brittle like vinyl

● Color stable factory finishes in a wide range of colors, with dual color (different inside and outside) available

● Non conductive, so it will not transmit heat, cold or electricity the way metal frames do

● Good fire performance: glass fiber does not burn, and the cured thermoset resin does not melt or drip the way vinyl does

● Inert once cured, with no VOCs in service, no chlorine and no plasticizers, and lower embodied carbon than aluminum over a long service life

● Excellent acoustic performance for quieter interiors

● Strong enough to carry triple glazing, vacuum glass and impact glass while keeping frames slim

DISADVANTAGES OF FIBERGLASS:

● Fiberglass is a premium material, typically priced above vinyl, though very competitive with high end wood and aluminum for the performance it delivers. Polyurethane fiberglass costs more again than the polyester most fiberglass windows use

● Fewer manufacturers produce true pultruded fiberglass systems, so availability and custom shapes can be more limited than aluminum

THERMALLY BROKEN ALUMINUM

A frame window with a barrier in between the inside and outside window frames that will prevent the conductive thermal energy loss. These systems come in many different designs for both contemporary and traditional homes. Many people use aluminum because you can get a steel look without the high cost associated with steel. The durability and low maintenance of Aluminum once painted or Anodized is one of the significant reasons for it use. Another, Aluminum is a Green Building component that can easily be recycled. Most of our manufacturers have 40 % or more recycled aluminum in the extruded profiles.

ADVANTAGES OF ALUMINUM:

● Aluminium is currently the most cost-effective option on the market

● Aluminium doors and windows are customisable – particularly for unusual openings

● Aluminium comes in an endless variety of custom colors

● Aluminium windows and doors are easy to install

● Aluminium is virtually maintenance free

● Aluminium windows and doors have a modern, streamlined design

● Aluminium will not rot or perish

DISADVANTAGES OF ALUMINUM:

● Aluminium insulation properties are dependent on glazing selected

WOOD WINDOWS

Wood windows with no cladding on the exterior are very popular for historic homes and neighborhoods where historical replication is king. These type of windows can obviously be painted or Stained any color because you’re applying it directly to a wood surface. The biggest drawback is that over time, Mother Nature plays havoc with the exterior and you will have to maintain them. Depending on where you live, what type of weather you incur, and the strictness of your local building or home association codes, you may have to re-oil or paint the exterior as often as every 2-3 years to protect the wood from aging and maintain the look required.

ADVANTAGES OF WOOD:

● Wood is aesthetically pleasing

● Wood has good natural insulation properties

● Wooden doors and windows are energy efficient

● Wooden doors and windows come in a variety of finishes

DISADVANTAGES OF WOOD:

● Wooden doors and windows require regular maintenance

● Wood is more expensive than aluminium after glazing and painting or varnishing

ALUMINUM CLADDING

An aluminum clad exterior has many assets. It’s virtually maintenance-free, it can be painted any color you want, and it offers extremely sturdy protection to the exterior of your window. But it’s important what type of aluminum cladding you’re getting. Extruded aluminum in rain screen form is much thicker, more solid and usually a bit more expensive than roll-form aluminum, which is thinner, flimsier. If you’re looking at cross-sections, the difference between extruded aluminum and roll-form is easy to see. The disparity in strength would be similar to the difference between a metal pipe and an aluminum can. There is a drawback with aluminum cladding in that it is more conductive than wood and upvc, thus making it slightly less energy-efficient.

ADVANTAGES OF ALUMINUM:

● Aluminium comes in an endless variety of custom colors

● Aluminium is virtually maintenance free

● Aluminium clad windows and doors have a modern, streamlined design

● Aluminium will not rot or perish

DISADVANTAGES OF ALUMINUM:

● Aluminium insulation properties are dependent on glazing selected.

uPVC WINDOWS

uPVC, also known as Unplasticized Polyvinyl Chloride, is a low-maintenance building material used as a substitute for painted wood, mostly for window frames and sills when installing double glazing in new buildings, or to replace older single glazed windows. uPVC doors and windows unlike wooden doors, are not prone to rotting, flaking, rusting, fading, or corroding. They have a very low thermal conductivity as a result of the type of materials used in manufacturing.

ADVANTAGES OF uPVC:

● uPVC frames are lightweight, durable and resistant to pollution

● uPVC windows need little maintenance with only regular cleaning.

● uPVC windows are a good insulator to keep heat in

● uPVC windows have a modern look suitable for contemporary buildings

● uPVC windows are less expensive than timber windows

DISADVANTAGES OF uPVC:

● uPVC windows and doors are prone to sagging

● uPVC windows and doors still lag behind wooden or aluminium doors when it comes to colors and customization options

● uPVC has a low scratch resistance

● uPVC is not stable against solar radiation and heat and with a passage of time it may fade or become brittle.