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How FIBREX shapes up
The table below shows how aluminium, Fibrex, PVC-U and timber compare in terms of maintenance, rigidity, heat resistance and thermal insulation.
	Decay	Stiffness	Expansion	Conductivity
Aluminium	0%	700,000	2.3	158.87
Fibrex	0%	56,000	2.2	0.173
PVC-U	0%	28,000	7.2	0.173
Treated pine*	10%	70,000	0.45	0.121
* Untreated pinewood decays by 50%
Decay is expressed as a percentage weight loss due to the material rotting; lower values mean less maintenance.
Stiffness, or modulus of elasticity, is expressed as the pressure in kg/cm2 before the material distorts; lower values mean thicker window frames to support glazing. The figure for aluminium was supplied by Technal.
Expansion is expressed as the percentage increase in surface area for each degree Centigrade rise; lower values mean less stress on joints in hot weather and thinner seals with walls.
Conductivity is expressed as the heat loss in watts per square metre for a one degree C difference in temperature; lower values mean less heat loss.