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Polyvalley Technology Co., Ltd.
TEL:+86-22-5967 2888
FAX:+86-22-5967 3666
EMAIL: info@polyvalley.com
ADD:No.2 Hongwang road Polyvalley technology park, Wuqing Tianjin, China
Contact us  
Polyvalley Technology Co., Ltd.
TEL:+86-22-5967 2888
FAX:+86-22-5967 3666
EMAIL: info@polyvalley.com
ADD:No.2 Hongwang road Polyvalley technology park, Wuqing Tianjin, China
Supports>>F.A.Q

Frequently Asked Questions


1. Do I really need to buy Polyvalley's recommended closure strips and screws for corrugated panels?
Yes. Polyvalley products are a system meant to provide the best possible installation. Proper use of the complete system (panels, closure strips, fasteners, etc.) greatly reduces the possibility of problems and insures that product warranty will be honored.

2. Why do I have to pre-drill fastener holes in roofing with corrugated panels?
Pre-drilling the holes insures the panels will have room to expand and contract properly with temperature change. Skipping this step can lead to distorted or warped panels.

3. Do Polyvalley products keep the "heat" out?
To a certain extent. Polyvalley sheets are available in a variety of colors each with its own heat and light transmission properties. While most Polyvalley sheets block 100% of harmful UV radiation, there are variations in heat and light transmission. Clear sheets allow most solar light and heat through while opaque colors are more reflective.

4. How long do Polyvalley Sheets last?
Polyvalley supplies individual product warranties against most types of failures.
The life expectancy can be as much as 30 years, depending on professional installation practice and environmental factors like air pollution, winds, and erosion by sand particles.

5. How do I cut these sheets?
Easily, Polyvalley sheets may be cut with either a circular saw (using a very fine blade, e.g. plywood, etc.) or a jig saw. For best results it is often better to cut a few sheets at a time to reduce vibration.
Also, if using a toothed circular saw blade, better results may be seen running the blade backwards. Sheets may also be cut by hand by carefully using tin snips or a utility knife. For further information please refer to our product manuals.

6. What should I use to clean my panels?
Warm water with a mild household detergent can be used. Wipe off any remained dirt with a soft cloth and wash again. NEVER use a solvent based cleaner (ammonia, etc.). AVOID using sponges or brushes that can scratch the panels surface.

7. In roofing with corrugated panels, what are purlins and closure strips?
Purlins are cross members running across the rafters of your structure. Closure strips match the corrugation pattern of the panels and are attached to the purlins.

8. In roofing with corrugated panels, where should I start?
You can choose to install left to right, or right to left, or start at the middle and continue to both sides.
It is recommended to Always advance against the dominant wind at the site.
Never start at both sides, or at any two separate points.

9. In roofing with corrugated panels, should I insert screws at valley or crest points?
Crest fixing should always be preferred.

10. Is it OK to fix screws by a power screwdriver?
Adjustable electric screwdriver is allowed, provided you set the torque to the minimal needed, in order to prevent over-tightening and local deformation of the panel.
For that reason, pneumatic tools should be avoided.

11. Is it OK to walk over roofing sheets while in storage, during or after installation?
No. In case it can’t be avoided during installation, use stepping ladders or crawling boards.

12.How should I store packed sheets?
Store in a protected, shaded, ventilated site, with no direct exposure to sunlight and winds.
In outdoor temporary storage cover with opaque protective film, and avoid PVC films and heat-absorbing materials.
Please note: Surface protective films that cover sheets are highly sensitive to heat and direct sunlight. Excessive heat and direct sunlight before taking off the film can cause gluing of that film to the sheet surface, after which it will not be practically possible to remove it from the sheet!

13. Why are there polyethylene films on certain sheets and should I peel it off?

The surface films in certain sheets are needed for protection against dirt and scratching, and also used to carry important information to the installer and final customer.
The indication of the UV protected side that should be installed facing outwards is extremely important.
It is recommended to peel off the protective films only after installation. In case this will not be feasible and the film will be peeled off before laying the sheets, it must be remembered to at least mark the UV protected surface, so that the sheet will not be installed inside out.

Please also note: Surface protective films that cover sheets are highly sensitive to heat and direct sunlight. Excessive heat and direct sunlight before taking off the film can cause gluing of that film to the sheet surface, after which it will not be practically possible to remove it from the sheet!

14.Can the sheets be curved?
Yes. Sheets can be cold-curved and serve in arched shapes, provided the relevant Polyvalley specifications for minimum radius in cold curving are followed.
Solid sheets can be cold-curved in any direction.
Corrugated sheets can be arched so that the corrugations themselves are curved (lengthwise).
Multi-wall sheets can be arched so that the actual ribs will be curved (lengthwise).
Curving is not recommended across the ribs direction.

15. Can these sheets catch fire?
Yes. In principle all plastic materials are flammable, and will catch fire in presence of exterior flame.
The ignition temperature of polycarbonate sheets is 490ºC (915ºF), and PVC sheets 391ºC (736ºF).
Both materials are self extinguishing, and fire will decay when the exterior flame source is removed.
Compared to PC and PVC, acrylic sheets are more flammable.

16.Do the sheets expand in heat?

Yes. Plastic sheets expand with heat, and shrink with cold.
As engineering plastics, PC and PVC demonstrate limited expansion/contraction Vs other plastics, however this change in dimensions should be considered. The use of enlarged screw holes in corrugated sheets (and aluminum profiles in multi-wall and solid sheets) are standard methods that should be followed. Always use the guidance in Polyvalley installation instructions.

17. Do plastic roofing sheets really block UV radiation?

Some of them do. Rigid PVC and polycarbonate sheets are practically opaque to UV radiation, making them a perfect barrier against this harmful radiation.
On the other hand, acrylic roofing sheets generally transmit a considerable portion of the UV radiation.

18. If polycarbonate sheets block UV radiation, why is there a ‘UV side’ to face outwards?

Polycarbonate blocks UV radiation by absorbing it. This absorption mechanism might degrade the material, and the sheet has to be protected against it. Protection to the sheet is achieved by coating it with a special material that converts the UV radiation into heat that emits to the external air layer.
In order to protect the sheets, they must be installed with the marked UV protective layer facing outside. Although sheet products can also be UV protected on both sides, most of the sheets are protected on one side that is marked clearly.


19. Should I paint the structural rafters with any paint?
Yes, but be sure to paint only with light or white color.
Do not use dark colors like black or brown, that can absorb and reflect intensive heat.

 

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