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Designing a Pitched Roof Extension: What should you consider?

Designing a Pitched Roof Extension: What should you consider?

Whether you would like to add a roof to your porch, gazebo or pergola to refresh your outside space, it is always better to use semi-transparent roofing materials that will let in plenty of light and add lots of style. When planning outdoor-roofed areas such as patios, carports, pergolas, and conservatories, builders and homeowners have many factors to consider. Here are some tips to help you choose the best solution and achieve the best results.

A Guide to Choosing the Right Polycarbonate Roofing Sheet for Your Home Improvement Project

The first consideration is the glazing product you wish to choose. DIY polycarbonate roofing products can vary in terms of their light transmission, impact resistance, load bearing capabilities and thermal insulation. The differences arise from the sheets' structure, thickness, and tint. Polycarbonate glazing options can affect the outcome of your DIY project in a few ways:


Heat-Blocking and Shading

Sheets with a high shading coefficient will ensure you have a comfortable outdoor patio in warm, sunny climates. Consider using smart colours that selectively block out the infrared radiation and reduce the heat build-up under the roof.

On the other hand, if the summer in your region is short and/or not very hot, clear roofing sheets would allow you to enjoy longer hours of daylight on your patio or porch in cold climates. The winter months will be perfect for sitting in a sunroom or conservatory extension.


Impact Resistance and Load Bearing

You shouldn’t overbuild. Choose a material that is appropriate for the local conditions. Impact resistance and load bearing requirements are variables that change from place to place. You do not need to choose a roof that is more impact and heavy load resistant if you don't expect to see snow, hail or strong winds. On the other hand, building too light in an area that is prone to extreme weather conditions could result in damage that could have been avoided. Lightweight corrugated polycarbonate sheets of 0.8mm thickness are an excellent choice for subtropical climates, but thicker sheets, either corrugated or flat, are a better choice for storm-prone areas.



Insulate your building

The last but not least is thermal insulation. Airflow and ventilation are maximized with open patios and gazebos. In these cases, thermal insulation of the roof is not a concern. However, what about closed verandas and sunrooms? Good thermal insulation might come in handy during the cold winter months. A good solution may be multiwall sheets, or double-glazed solid polycarbonate sheets.



The winter months will be perfect for sitting in a sunroom or conservatory extension.

Plan the Roof Slope to Allow for Proper Drainage 


Not all roofing sheets drain rainwater the same way. For example, corrugated sheet roofs require a different slope than flat sheet roofs. The slope of patio covers made from flat polycarbonate sheets, whether solid or multiwall, should be at least 3 degrees. The slope required for a roof covered with corrugated polycarbonate sheets (also known as profiled sheets), such as SUNTUF DIY, is   5.7 degrees.


Does that sound complicated? A simple way to measure the slope is to convert degrees into percentages of the roof length. As a rule of thumb, a flat roof must have a minimum percentage of 5% and a corrugated roof must have a minimum percentage of 10%. However, before we memorize these figures, we should first understand how these factors are calculated.



As a rule of thumb, a flat roof must have a minimum percentage of 5% and a corrugated roof must have a minimum percentage of 10%.


A roof slope percentage is calculated by measuring how high or low a roof rises or falls over a given distance. In other words, if a roof slopes 50/1,000, it rises or falls 5 centimeters over one meter. On the basis of this ratio, the roof slope would be 5%. Remember: Corrugated sheets require a slope of 10%, while flat sheets need only a slope of 5%.

In order to calculate the slope length, for example, for a 200mm/4,000mm roof, you need to add 5mm for every 1000mm of the roof base length: 4 times 5mm equals 20mm. In addition, you should allow 100-150mm of overhang at the top and bottom. This results in a 4170mm long sheet from a 4000mm long base.

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Curve Your Roof Extension to Get Stunning Results


How should polycarbonate sheets be curved in order to create an arched roof? Can corrugated sheets be curved at all? What is the minimum radius for bending polycarbonate sheets? Polycarbonate sheets can all be cold bent during installation, but each has a minimum radius that should not be exceeded. The radius of an arc or segment is the radius of the circle in which it is contained



When it comes to polycarbonate flat sheets, whether solid like PALSUN or multiwall like SUNLITE, the arch radius should not be smaller than the sheet thickness multiplied by 200. This means that, for example, a 4mm sheet can be cold bent to an arch radius of 800mm, or 80 centimeters.

The SUNTUF profiled sheets can also be cold bent to create arched shapes. Depending on the corrugation ridge height and the thickness of the sheet, each profile has its own radius limitations.



Polycarbonate sheets can all be cold bent during installation

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