Polycarbonate Sheet Selection Guide for Warehouse and Industrial Skylights

Factories, warehouses, logistics centers and steel-structure buildings usually have large roof areas. Properly designed polycarbonate daylighting strips can introduce natural light into the building and improve daytime lighting in production areas, storage-rack areas and passageways.

For overseas projects, however, polycarbonate daylighting sheets should not be purchased based only on “thickness” and “price.” Sunlight intensity, temperature differences, wind, snow, roof profile, support spacing, fire requirements and installation methods at the project location can all affect the final selection.

A more reliable selection process is to confirm the roof structure and service environment first, then select the sheet type, daylight effect, thickness, UV structure and special functions, and finally check the installation allowance and technical documents.

1. Confirm the Project Conditions Before Asking About Sheet Thickness

When overseas customers request a quotation, one of the most common questions is, “Should we use 1.5mm or 2mm?” In fact, thickness is only one parameter in the selection process. Before recommending a product, the supplier normally needs to know:

• The country and city of the project, and whether the area has long-term high temperatures, strong UV radiation, typhoons or snow;
• Whether the roof is color-coated steel roofing, profiled metal roofing or an independently framed skylight;
• The support spacing between purlins or beams;
• Whether the daylighting area requires high transparency or reduced glare and bright spots;
• Whether the local project requires a specific fire rating, technical data sheet or third-party test documents.

Only after these conditions are confirmed can the sheet type, thickness and fixing method have practical reference value.

2. Select the Appropriate PC Sheet Type According to the Roof Structure

2.1 Polycarbonate Corrugated Sheet: Suitable for Color-Coated Steel and Profiled Metal Roofs

Polycarbonate Corrugated Sheet has a corrugated or trapezoidal profile and is commonly used for daylighting strips on factory and warehouse roofs. The primary selection criterion is not simply the length or width, but whether the profile can accurately overlap the existing metal roof.

Before purchasing, provide the roof cross-section drawing, pitch and profile-height dimensions, a metal-sheet sample or clear side-view photographs. Guoweixing can produce a matching Polycarbonate Corrugated Sheet according to the project roof profile, length, color, daylight effect and single- or double-sided UV requirements.

2.2 Polycarbonate Hollow Sheet: Suitable for Framed Skylights Where Thermal Insulation Matters

Polycarbonate Hollow Sheet has an internal hollow structure, is lightweight and provides a certain level of thermal insulation. It is suitable for independently designed skylights, enclosed walkways, greenhouses, canopies and industrial buildings with supporting frames.

Polycarbonate Hollow Sheet normally requires matching profiles, edge-sealing tape and connectors. In addition to thickness, the sheet structure, support method and end-sealing solution should also be confirmed.

2.3 Polycarbonate Solid Sheet: Suitable for High Transparency, Small Areas or Special-Shaped Structures

Polycarbonate Solid Sheet is a flat solid sheet with high transparency and good impact resistance. It is commonly used for small daylighting windows, curved canopies, factory side windows, transparent partitions and special transparent roof structures.

Large Polycarbonate Solid Sheet installations require properly designed frames and supports. The sheet’s toughness does not mean that span and fixing methods can be ignored.

3. Choose Clear Sheets or Milky-White PC Diffusion Sheet According to Indoor Daylight Requirements

The highest transparency is not always the most suitable choice. Overseas warehouses and production workshops often care more about whether the indoor light is uniform than about a single light-transmission value.

Clear PC sheets can introduce more natural light, but when used over a large area, strong sunlight may create localized bright spots and glare. PC Diffusion Sheet disperses direct light, making the light in storage-rack areas, assembly areas and production lines softer and more uniform.

PC Diffusion Sheet is made by adding diffusion material to a base PC sheet and is normally milky white. Actual light transmission varies with the formulation and color. Guoweixing can produce milky-white PC Diffusion Sheet according to project requirements. Because it is a special sheet, the color, target light transmission, sheet type, thickness and application should all be confirmed when requesting a quotation.

4. Evaluate Thickness Together with the Profile, Support Spacing and Local Climate

PC daylighting sheets with the same thickness may perform very differently when the profile and support spacing are different. Selection should focus on:

• The sheet profile or internal structure;
• The distance between purlins, beams or frame members;
• Sheet length and roof slope;
• Local maximum wind speed, typhoon risk and installation height;
• Whether there is a risk of snow, hail or falling maintenance tools;
• Screws, pressure bars, connectors and overlap methods.

In general, larger support spacing, stronger wind and snow conditions, and longer sheets place higher requirements on sheet thickness, profile stiffness and the fixing system. Professional selection is not about recommending the thickest sheet, but about matching the sheet, supports and installation method.

5. Confirm the UV-Protection Structure for Outdoor Projects

PC sheets exposed outdoors for long periods are continuously affected by ultraviolet radiation and temperature changes. Without suitable UV protection, the sheets may gradually yellow, lose light transmission, show surface ageing or become brittle.

Industrial skylights should preferably use products with a UV co-extruded protective layer. Guoweixing outdoor-grade PC products include a UV-protective layer that can block 99% of ultraviolet radiation, helping to delay yellowing, loss of light transmission, surface ageing and embrittlement. For single-sided UV sheets, the UV side must face the sun during installation. Double-sided UV sheets are more suitable when both sides may be exposed to sunlight, the installation direction is difficult to control or the project has higher environmental requirements.

Guoweixing can produce Polycarbonate Corrugated Sheet, Polycarbonate Hollow Sheet and Polycarbonate Solid Sheet with single- or double-sided UV protection according to project requirements. Before formal purchasing, confirm the UV structure, installation direction, product grade, warranty conditions and corresponding technical documents rather than only confirming that the product “has UV.”

6. Confirm the Fire Rating and Test Documents When Fire Performance Is Required

The main purpose of a flame-retardant PC sheet is to slow burning and flame spread when the sheet comes into contact with a fire source, and to stop sustained burning as quickly as possible after the fire source is removed. This helps reduce the risk of fire continuing to spread through daylighting strips or building-envelope structures and provides more time for evacuation and firefighting response.

Flame retardant does not mean non-combustible, and not every PC sheet marked “flame retardant” can achieve UL 94 V-0. Actual fire performance may vary with the raw-material formulation, sheet type, thickness, color and structure. Overseas projects should first confirm local building regulations, the application, fire requirements and tender documents before selecting the appropriate grade. When UL 94 V-0 is specifically required, Guoweixing can produce PC V0 Solid Sheet through material modification and formulation adjustment according to the customer’s requirements.

When requesting a quotation, clearly provide the sheet type, thickness, color, structure and required fire rating, and verify that the test report matches the actual purchased product. Do not substitute a report for another thickness or a different product structure.

7. Confirm Sheet Weight, Individual Sheet Size and Transport Conditions in Advance

Industrial factory and warehouse skylights usually cover large areas. In addition to sheet performance, the selection should therefore consider the additional roof load, individual sheet size, transport method and on-site installation conditions. Polycarbonate Solid Sheet has a density of approximately 1.2g/cm³, compared with approximately 2.5g/cm³ for ordinary glass. At the same thickness, Polycarbonate Solid Sheet weighs about half as much as ordinary glass. The lower weight helps reduce transport, lifting and additional roof loads and is suitable for large-area industrial daylighting structures.

However, lower weight does not mean that sheet thickness or the support structure can be reduced arbitrarily. Final selection should still be based on the sheet type, support spacing, sheet length, wind and snow loads, and fixing method.

For overseas projects, the individual sheet length, container-loading method, protective packaging, on-site unloading and lifting conditions should also be confirmed in advance. For extra-long sheets in particular, even when the factory can produce them, it is necessary to confirm that they can be loaded into a container, transported and brought into the construction site, so that completed products do not become impossible to deliver or install.

8. What Information Should Be Provided Before Quotation and Selection?

The more complete the information, the easier it is for the supplier to determine the sheet type, thickness, profile, UV structure and quotation. For overseas projects, the following information is recommended:

9. How to Select a Reliable Polycarbonate Sheet Manufacturer?

For overseas buyers, supplier selection is as important as product selection.

A qualified manufacturer should provide:

9.1 Custom Manufacturing Capability

Industrial projects often require:

• Special roof profiles;
• Customized sizes;
• Different colors;
• Special functions.

A manufacturer with customization capability can reduce installation problems.

9.2 Quality Documentation

Professional suppliers should provide:

• Technical Data Sheet (TDS);
• Fire test reports;
• UV performance information;
• Product specifications;
• Quality inspection documents.

9.3 Export Experience

International projects require experience with:

• Export packaging;
• Container loading;
• Long-distance transportation;
• Documentation support.

9.4 Technical Support

A reliable supplier should help customers with:

• Product selection;
• Installation recommendations;
• Sample approval;
• Project specification confirmation.

Guoweixing provides customized polycarbonate solutions including:

Polycarbonate sheet selection for industrial skylights should focus on whether the product matches the project, rather than comparing thickness and price alone.

Different applications place different priorities on profile, daylight transmission, thermal insulation, UV protection and fire performance. The table above can be used as an initial selection reference. The final specification should still be determined according to the project drawings, local climate, support conditions and actual application requirements.

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