Choosing the right thickness of plastic sheet to use can make or break a project. This calculator makes it easy to choose the best plastic roof sheets for your application.
Too thin? Too thin plastic sheets will sag or flex or break.
Too thick? Too thick plastic sheets won’t cause issues but may be over specified.
There’s a host of plastic sheeting types available, including Perspex sheets, polycarbonate sheet and twinwall sheets; each with its own spanning capabilities.
Should I choose the thinnest thickness plastic sheet available?
No, although cheap plastic roofing sheets may save some upfront costs, do not be tempted to risk it.
RapidKey® plastic sheet thickness calculator from Clear Amber calculates the suggested minimum thickness to use based on your rafter spacing.
This calculator provides an excellent idea of what plastic sheet thickness to start with; however, bear in mind that many applications will require thicker roof sheets, depending on the location, wind exposure, and other factors.
Remember also, it highly depends on your roof type. Some thicknesses like, Axiome® 10mm polycarbonate, are a great budget option for lean tos but can be too flexible in an open garden installation.
How does the spanning of solid versus twinwall polycarbonate compare?
Solid and twinwall sheets both share the benefits of being polycarbonate sheets, such as impact resistance and quality, but offer polar opposite spanning potential.
Many solid plastic sheets like perspex and polypropylene have a low impact resistance and brittleness which polycarbonate avoids. This means solid polycarbonate has a higher impact resistance than its sister twinwall version.
Solid polycarbonate sheets have a higher weight per m2 than multiwall options but are manufactured in a thinner range of thicknesses. This means it’s not possible to directly compare their spanning capabilities.
Does the plastic sheet colour affect spanning?
No, the colour of the plastic sheet that you choose will not affect the span capabilities. Only the thickness and structure of the sheet have an impact.
For more applications a clear plastic sheet is the most popular choice, but we also manufacture bronze and opal tints. Plus, many more tint types.
Do corrugated plastic sheets span the same as flat sheets?
No, corrugated plastic sheets have a completely different strength axis: in simple terms, they should be supported with supports across the width of the sheet rather than down the length direction.
For this reason, the strength of corrugated plastic is primarily down to the material it is made from rather than the thickness.
For example, corrugated PVC sheets are known to be affordable but they have limited strength when compared to the likes of a Corrapol Stormproof sheet.
Even a very thick PVC corrugated sheet would not match the strength of Corrapol® Stormproof as the materials are poles apart in robustness!
Would you like further help choosing plastic roof sheets for your project?
Contact our team of experts on live chat and they’ll be able to assist. Remember, it is always best to check with a structural engineer if you are unsure on what the optimal thickness is for your specific application.
