Fiberglass Advantages
Fiberglass Frame
- Fiberglass Profile Frame
- Fiberglass Sash
- Insulated Frame
- Exterior Brickmould or Panning
- Insulating Glass Unit
- Interior Jamb Extension
- Foam Insulated Weather Stripping
- Glazing Bead
Fiberglass Advantages
High Dimensional Stability
Low Thermal Conductivity / Energy Efficient
Environmentally Friendly
Structural Integrity
Fiberglass is 3x stronger than wood
Fiberglass is 3.5x stronger than vinyl/wood composites
Fiberglass is 8x stronger than vinyl
Low Maintenance
Fiberglass replacement windows are efficient and maintenance-free
Fiberglass windows are grabbing a bigger share of the replacement window market every year. A decade ago, only a handful of northern and Canadian companies offered fiberglass windows because of their high energy efficiency. Today, some of the major name-brand manufacturers are offering them along with their existing line of standard replacement windows.
Fiberglass is the strongest window frame material available other than metal which is not a natural insulator. The frames are made of about 75 percent glass fibers and 25 percent resin. The glass fibers are made from silica sand which is melted and spun. Silica sand is in abundant supply.
Another advantage of a fiberglass frame is it reacts to outdoor temperature changes much like glass panes do. This makes the entire window system and weatherstripping more airtight. Internal stresses are reduced because all the components are expanding and contracting at about the same rate.
The pultrusion process, by which most fiberglass windows frames are made, is different than for making boat hulls. For the frames, long glass fibers are pulled through a die (similar to a cookie cutter) and coated with resin. It is a thermoset resin so once it sets up, heat cannot weaken it. For dark colored frames exposed to the hot southern sun, this is an advantage over vinyl.
Fiberglass is maintenance-free and will never crack, split or warp, even in humid climates. If you prefer the indoor look of natural wood, you can order fiberglass frames with a real wood veneer of hemlock, oak, cherry, etc. The veneer is permanently bonded to the indoor surface of the frame.
Fiberglass frames are painted at the factory. There are usually three to five standard colors available with custom colors at a slight surcharge. Spilt colors (different indoors and outdoors) are also available. Fiberglass is easy to paint yourself, so you can change the color anytime.
The hollow fiberglass frame is an effective natural insulator, but you can select ones with additional foam insulation inside the frames. Since you are considering high-quality windows, pay a little extra for the most efficient glass options such as low-e argon, triple-pane or Heat Mirror.
Fiberglass Properties Compared to Traditional Materials
Window Material Properties
PART 1: MODULUS
These are the modulus numbers for common window frame materials:
- Aluminum 11,000,000
- Fiberglass 6,500,000
- Wood 1,450,000
- Vinyl 410,000
The modulus numbers tell us the stiffness of a material. This is an important number to know when selecting a window material.
Example
Using a 1’ long piece of 1″ hollow square tubing with a 0.90″ wall thickness, and a 40 lb. load on the end of the tube. * Wood is solid.
PART 2: YIELD STRENGTH
These are the yield strength numbers for common window frame materials:
- Fiberglass 60,000
- Aluminum 35,000
- Vinyl 8,000
- Wood 800
Yield strength and yield stress are the same. Yield strength indicates the margin of safety built into a window.
Example
Using the same tubing we can indicate how much weight the material can withstand before breaking.
PART 3: COEFFICIENT OF EXPANSION
These are the expansion numbers for common window frame materials:
- Fiberglass .000004
- Aluminum .000012
- Vinyl .000029
- Wood depends on how much moisture is absorbed
Example
Building a sash, we heat it up to 120 °F and watch what happens.
Fiberglass Sash
Nothing happens to the glass and sash. They both expanded at the same amount.
0.007″ – about the same thickness as 1.5 sheets of paper
Aluminum Sash
The sash expanded more than the glass.
0.015″ – about the same thickness as 4 sheets of paper
Vinyl Sash
The sash expanded more than the glass.
0.045” – this can cause leaking seals
PART 4: THERMODYNAMICS
These are the thermodynamic properties for common window frame materials:
- Fiberglass 0.11 at 280°F heat deflection
- Aluminum 0.11 at 140°F heat deflection
- Vinyl 0.20
- Wood 140
Example
Heat loss thru different window frame materials excluding the glass package
Glass Performance Data
Shading Coefficient = SHGC / 0.87
*LSG – Light to Solar Heat Gain Ratio
Performance values are based on 3 mm Glass COG
Fiberglass Structural Integrity
High Dimensional Stability
Fiberglass expansion rate is nearly identical to the rate of glass. This low thermal expansion rate translates into virtually zero seal failure. Which makes the entire window system and weather stripping more airtight. Internal stresses are reduced because all the components are expanding and contracting at about the same rate.
Material Expansion Rates
