Fiberglass vs Vinyl Replacement Windows

Are fiberglass replacement windows truly the best technology out there for insulation and noise reduction? Is vinyl subpar to fiberglass? As these are different materials they have their respective advantages and disadvantages. For the sake of comparisons, let's stick to premium vinyl versus Fiberglass. 


You will get better thermal numbers out of premium vinyl: double pane, triple pane, five layer etc. 


Fiberglass can be painted (more easily) and is more thermally stable (less expansion and contraction than vinyl).

Sound transmission has about 99% to do with the glass and much less the frame.

Fiberglass (being comprised largely of glass) does not, by itself, have as good an R-Value as vinyl. All premium frames will usually be insulated with some sort of foam so this issue is somewhat mitigated.

Fiberglass has more tensile strength and rigidity when compared to vinyl of similar thicknesses. This is the reason that most fiberglass windows can get away with thinner profiles.

Fiberglass has a better look as it gave a closer appearance to wood.

Fiberglass is typically about double the price of a premium vinyl.

So why do fiberglass windows typically cost a lot more? 

The cost of manufacturing a lineal of fiberglass is significantly more than vinyl. The cost of assembling that window is also more.

That would likely amount to about a 20-30% increase in overall cost to manufacture.

Thus we can see that both fiberglass and vinyl have their own uses. What you choose will depend a lot on your individual preference.