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Kerttrade a minőségi műanyagok szakértője
Plastic trade, pmma, polycarbonate, pvc sheets, at promotional prices, directly from distributors stock.

Roofing calculator

Roofing typeSheet typeDimensionsRequired material
This is the step 0

Please choose the kind of the roofing!


Our calculator offers the different types of the polycarbonate and acrylic sheets, and changes the input method of the dimensions according to your decision.


You can use the basic roofing types for calculating other roofing or covering types. For example you can use flat roofing to calculate the material needs of a window barrier or interior partition wall.

Please choose the desired roofing material!


Please consider that certain thicknesses or types are not suggested so much or even at all for some application. However you might choose thinner sheets than 16 mm for a wintergarden's roof, but we never suggest you to choose thinner than 16 mm. For a patio roof it is never suggested to buy thicker sheets than 16 mm!

Please enter the specific dimensions of the polycarbonate or acrylic roofing, and the details of the supporting structure!


The width of the spans determine the width of the fixing profiles. For a workmanlike  installation of the plastic sheets we always suggest to use at least 60 mm wide span structure and therefore you are suggested to buy the 60 mm wide profile system, as the plastics have always high thermal expansion. The 50 mm wide profile system accomplish only the minimum of the suggestion of the producers, however there are some cases when it is still acceptable.


After entering the width (the dimension perpendicular to the slope drection) and the length (dimension in slope direction) of the roofing please click on the 'calculation' button the get the suggested number of the spans.


You may of course choose different span quantity!

You are always allowed to choose more spans than the suggested quantity as this won't affect negatively the load bearing capacity of the polycarbonate and acrylic sheets, just the look of the roofing, and you only have to pay more for the accessories.

On the other hand our calculator allows you to use less spans only untill their distance fulfills the regulation of the producers which is based on the load bearing capacity of the choosen sheet type and the national regulation of the weathering loads, which differs from country to country.

Please don't forget that the number of the spans is always more by one piece as the desired number of the gaps between the spans!


If you are unsure how to build a safe and workmanlike supporting structure, then it is advised to ask the help of an engineer or a professional installator company!

Our Company can't take any responsibility of any damage or injury caused by an insufficient supporting structure or badly planned roofing!

If you are satisfied with the calculation result you may order them from our webshop by clicking on the "Add to cart" button and following the steps of ordering.


If you want to buy the materials later, you might print the material list, or you may ask an individual offer from us.

The installation profile need of the 4, 6 and 8 mm thick multiwall polycarbonate sheets are higher than the thicker ones. We suggest to use these thicknesses for curved glazings where the bending radius is small.

According to the standard snow and wind loads, the suggested span distance of the 10 mm thick multiwall polycarbonate sheets is 70 cm. In special circumstances it can be rarified up to 105 cm.

The 16 mm thick multiwall polycarbonate or multiskin acrylic sheets offer the best price/value ratio in case of the 'open' glazings as their span distance can be aesthetically rare and their weather and hail resistance is quite well.

The suggested span distance is 105 cm which can be escalated to 120 cm economically.

The 20 mm thick multiwall polycarbonate sheet is the entry-level thickness for the conservatories. Due to its classic parallel inner structure they let more light in than the X structures sheets, but their thermal insulation is only at an expactable level. We don't suggest to use this thickness to patio roofs or any other 'open' roofings.

The suggested span distance is 105 cm. It is not economical to create wider one.

The thermal instulation of the 5M structured sheets are better then the similar thick multiwall polycarbonate sheet's general capability. Their loadbearing capacity is excellent, however for economical reasons we don't suggest to cover wider span distance than 105 cm as it became quite expensive due to the wasting of the material. On the other hand the purlin distance can be as large as 600 cm!