While aluminum is heavier and has high thermal conductivity and high electrical conductivity, as well as low corrosion resistance, pultrusion is the opposite: lightweight, non-conductive (thermally and electrically) and highly corrosion resistant. Pultrusion is approximately 30% lighter than aluminum.
Both aluminum and pultrusion are strong, but the dimensional stability of pultrusion is much higher. In addition, pultrusion are impact resistant and EMI/RFI transparent, whereas aluminum can easily dent and deform under impact and will interfere with transmissions.
The cost of aluminum may be comparable or even less than pultrusion, but because of corrosion and malleability of aluminum, the total long-term costs of pultrusion are less expensive. In addition, pultrusion may be a much safer option for many types of applications.
As for mounting cabinets, ladders roof mounted A/C’s. We place backers in customer requested areas, this can be EGS steel or solid composite backers depending on load requirements. All roofs are can be walked on for maintenance. These materials are used on RV’s and food trucks. The food trucks sometimes have several A/C’s and two restaurant style hood fans that are around 95lbs each.
R-value will vary depending wall thickness. Our 1” wall is around R7 and can be higher if XPS foam is used in place of EPS.