Multi-Wall Polycarbonate FAQs

Selection: Clear & Softlite offer maximum light and heat transmission, best for greenhouses and solar applications. Clear is not 100% optically clear. Channels in the polycarbonate create a vertical pattern. Bronze and white (also called opal or ice) reduce light and heat. White is more opaque and is often used to hide dirt that may accumulate on roof or images that are behind the polycarbonate. White also reflects the suns rays and will not accumulate heat the way bronze can. Bronze will reduce light and heat, but is most often an esthetic choice. Bronze will also expand and contract more, possibly creating noise on large sheets. Figure about 1/32″ per foot for 100 degrees of temperature change. For small greenhouses, the impact is minimal. To avoid problems follow guidelines for the Base & Cap System. Installation on a cold day with sheets touching, or jammed tight against a wall, can create problems as the sheet expands. The sheet absorbs some flexing, best to follow guidelines. The greatest amount of expansion and contraction can occur in the spring and fall. Cold nights and warm sunny days can result in dramatic temperature swings. During these times the sheet may make a creaking noise. Do not be alarmed, this is a normal effect of sheet movement as the polycarbonate expands or contracts along the framing members. On orders of poly over ten feet you will be sent an email explaining a foam tape option to deaden the noise.

What thickness to use? This is usually a pay now or pay later situation. Pay now for greater strength and insulation, or later for more framing to support the sheet and heat to keep the structure warm. Polycarbonate Selection and R-values of sheet.

What width should I use? 4 ft. easy to install on roofs & walls. 4 ft. wide crates lighter, costs less to ship. 6 ft. recommended only for walls.

Does poly. yellow from sun or damage from hail? Polycarbonate has warranty to not yellow or be effected by hail.

Design:

Why must polycarbonate be installed with channels running vertically? A small amount of moisture may gather in the channels. Vertical installation allows this moisture to drain.

Do you have a pop-on, removable panel system? Yes, see Pop-On Polycarbonate Panel System.

What is the bending radius of polycarbonate? See bending radius for various types of polycarbonate.

Install:

How do I cut polycarbonate? Circular saw with plywood blade or jig saw metal cutting blade.

Polycarbonate expands & contracts with temperature changes. How will this effect my installation? Sheet will expand in hot weather and contract in cold. Figure about 1/32″ per foot for 100º of temperature change. To avoid problems follow Install Details. Installation on a cold day with sheets touching, or jammed tight against a wall, can create problems as the sheet expands. The sheet will absorb some flexing, but best to follow our details. The greatest amount of expansion and contraction can occur in the spring and fall. Cold nights and warm sunny days can result in dramatic temperature swings. During these times the sheet may make a creaking noise. Do not be alarmed, this is a normal effect of sheet movement as the polycarbonate expands or contracts along the framing members. On orders of poly over ten feet you will be sent an email explaining a foam tape option to help deaden the noise. Sheets under 10 ft. are usually not an issue. Also, bronze, being a dark color, will get warmer in the sun and it will be hotter under the panel, even.

I left protective film on polycarbonate, installed sheet and now can not get it off. What can I do? At local hardware store pickup a product called Fels-Naptha. Wash sheet with this. Pull off film and clean with soap and water.

How to avoid dreaded backup of water into lower edges polycarbonate channels. The most common installation mistake is to not follow the Base & Cap Eave Detail. See Multi-Wall Base & Cap Install Details, especially “Eave Detail”. The 3/8″ self drill screws attach long leg of U-Profile to poly every 8″ on-center. Also, click on link “See Ends of Cap ” (top right of Eave Detail Page) for photo of this important detail and further instructions. Most leakage occurs at Eave, when customers do not follow the instructions. Leakage at this point results in water (laden with dust, dirt, pollen & pollution) backing up the channels, staining the inner channels. This problem is easily avoided by following our details to the letter. Vent tape, as other suppliers use at lower edge is not a solution. A loose fitting U-Profile with vent tape will allow water in and up channels, thru the vent tape. Our U-Profiles fit snug, but not too tight. The pressure of screws pinning U-Profile to poly, every 8″, slightly dimples the poly, creating an exceptional seal. Small leaks at joints of U-Profile and condensation in the channels drains out via weep holes in U-Profiles.

Polycarbonate Greenhouse and Sunroom Building Supplies