There are several different types of fiberglass cloth available, such as woven, biaxial, etc. In the United States, fiberglass cloth is specified by its weight per square yard. For example, 6 oz. fiberglass cloth weighs 6 oz. per square yard. In addition, each fabric weight will have a different thickness. Some of the more common types of fiberglass cloth are shown in the table below.
| Fiberglass Cloth Type / Weight | Thickness of a Single Layer** |
| Woven, 4 oz. | .008" |
| Woven, 6 oz. | .010" |
| Woven, 10 oz. | .016" |
| Biaxial, 17 oz. | .035" |
| Biaxial with mat backing, 24 oz. | .042" |
| ** These single-layer thicknesses are based on the average of multiple layers applied using the hand layup method. | |
To calculate the number of layers of fiberglass cloth needed to build a specific laminate thickness, divide the desired thickness by the thickness of a single layer of the type of fiberglass fabric you want to use.
The examples below indicate how much biaxial fiberglass cloth is needed to build a 1/4" thickness of glass. Note that biaxial cloth or biax is available with or without mat backing, and each type has a different weight.
Example 1: Biaxial Fabric without mat backing
- Fabric Weight = 17 oz. (per square yard)
- Single layer thickness = .035" (average of multiple layers applied using hand layup method)
- To build up 1/4" of biaxial fiberglass cloth, you would need approximately 8 layers.
.035" x 8 = .28 (or approximately 1/4")
Example 2: Biaxial Fabric with mat backing
- Fabric Weight = 24 oz. (per square yard)
- Single layer thickness = .042" (average of multiple layers applied using hand layup method)
- To build up 1/4" of biaxial cloth with mat backing, you would need approximately 6 layers.
.042" x 6 = .252 (or approximately 1/4")