Frequently Asked Questions

• Question: Why use the 4-layer instead of the 2-layer polycarbonate glazing?
  
• Answer: The 4-layer provides more insulation than the 2-layer, but only transmits 71% of the sunlight. The 2-layer 8 mm glazing transmits 76% of the light. That small difference in transmissibility provides faster plant growth, but also shortens the growing season requiring supplemental heat. Most commercial greenhouse operations use the 8 mm 2-layer glazing, but offsets the lower insulation value with significant fossil fuel consumption. The use of the 8 mm 4-layer is optimal for minimizing carbon emmisions in the harsh intermountain-west climates where there is an abundance of sunlight but also extremely cold temperatures.
  
  
• Question: I've lived in other locations that never use 4-layer glazing. Is glazing geographically dependent?
• Answer: CatchSunlight does not recommend 4-layer glazing for areas like Portland, Oregon. The minimal sunlight on the west side of the Casacades minimizes the amount of energy that transmits into a greenhouse. 4-layer glazing is suited to sunny areas that are cold. The high-intermountain west has minimal moisture content in the air so the majority of energy losses come from radiation. Radiative heat loss is proportional to the difference between the fourth power of the absolute temperature of the two incidental thermal bodies. In other words, in the high mountains, it is possible to have plants freeze even if the air temperature is above freezing because the space above the atmosphere is modeled nearly at absolute zero, and there is minimal insulation due to the lack of moisture content of the air in the high-desert regions. In this region, the radiative losses exceed the convective gains from the surrounding air resulting in frost year around in some locations. Oxygen and Nitrogen are virtually invisible to thermal radiation (hence global warming is dependent on water vapor and carbon) which means all the thermal energy in plants can be sucked out into the atmosphere even when the air temperature is above freezing. That's why 4-layer glazing is so important at high elevations.
  
  
• Question: Is shade cloth necessary with multi-layer polycarbonate panels?
• Answer: We don't use shade cloth with our 4-layer polycarbonate. Some growers do. Our experience is that if your plants are well established in the spring, before the intense heat of the summer, there is no need for shade cloth on your greenhouse. Many greenhouse operations that use the 2-layer polycarbonate panels use shade cloth for a portion of the growing season.
  
  
• Question: Agricultural Polyethelyne (PE) sheeting is much cheaper. Why use polycarbonate?
• Answer: Typical agricultural PE is about 25 cents a square foot per layer, depending on how much is being purchaced. PE initially transmits 74% of the light, but becomes cloudy over time, reducing the overal transmissibility down to around 66% in about four years. Furthermore, a single layer of PE provides very little protection from the cold. You can expect your crops to freeze anytime the temperature drops down about 4 degrees F under freezing in the high intermountain west geography if only one layer of PE is used without supplemental heat. Two layers of PE are used for most commercial greenhouses that use PE but that requires a blower to expand the gap between the layers which provides the insulation. That requires additional energy and consequently, a higher carbon footprint. Additionally, wind damage to PE is very common. Damage and loss of light transmissibility results in most greenhouse operations replacing their PE every four years, which represents a significant labor cost. The CatchSunlight polycarbonate panels are warranteed for 10 years and have been used for multiple decades without replacement. Furthmore, polycarbonate is resilient enough to withstand impacts that would otherwise destroy PE.
  
  
• Question: Does polycarbonate get damaged from the sun?
• Answer: Each panel has a 50 μm layer of UV resistant material to slow sun damage to the product. It is vitally important that the UV protected side be placed up during installation. This UV layer slowly errodes over time, which is why polycarbonate does not last as long as glass. Even though this errosion of the UV protected layer slowly occurs, the panels are warranteed for 10 years against significant yellowing, and have been installed for decades for some greenhouse applications.
  
  
• Question: Are the 1,379 ft² greenhouse kits engineered for a certain snow or wind load?
• Answer: These kits are not specifically engineered in accordance with the International Building Code for occupied structures for the intermountain west. They were designed to be stronger than the typical NRCS high-tunnel and have a peaked or gothic profile to assist in shedding snow. Their hoops are on 1 meter centers, and have some trussing, but are not designed with an engineered stamp. Some municipalities require such a stamp, but most rural locations rely on a single-use or agricultural permit for the installation of high-tunnels, which does not require an engineered stamp. This particular kit was designed to be different than the typical high-tunnel kits in that it is built more rigid to support a higher snow and wind load and to use multi-layer polycarbonate, which very few other kit providers have. The polycarbonate panels are very slippery so the snow typically falls off after minimal accumulations. Notwithstanding that, the user needs to ensure that deep snow accumulations are prevented, otherwise, structural collapse could occur. Engineering services can be rendered by local providers and additional stiffening can be added, but our observation is that this design works for our area with a little work during extreme situations.
  
  
• Question: The greenhouse kits CatchSunlight is selling cost around $10 a square foot. That's a lot more than a typical NRCS approved greenhouse kit. What's the difference?
• Answer: It is possible to purchase a high-tunnel greenhouse that uses just hoops, no trussing, and a single layer of PE for about $4.00 per square foot. The NRCS cost sharing program provides grants ranging from $2.76 to $7.00 a square foot. That program provides money to assist the buyer to purchase a greenhouse, but is not meant to pay for it, but is a "cost-sharing" program. The cheap high-tunnels available on the internet that are frequently used for the NRCS cost sharing program are a bargain, but often do not include end-wall materials, and frequently ignore bottom side wall construction materials as well. Furthermore, the single layer PE will last typically only four years. The weak frame cannot stand against the typical snow and wind loads in the intermountan-west. To put this in perspective, the Conley's Ranger model (www.conleys.com), which has a similar shape to the CatchSunlight model, runs around $30 a square foot if 4-layer glazing is specified, plus the added cost of shipping from California. At about $10 per square foot, you literally cannot build a similar greenhouse if you bought the material separately, even if wood is used. Our custom design and wholesale ordering enables CatchSunlight to sell these below the cost it would take to buy the wood or steel to construct a separate DIY design.
  
  
• Question: Do you recommend wood for greenhouse construction?
• Answer: No. Spend the extra money now on galvanized steel. CatchSunlight has built several wooden framed greenhouses. The humidity is so high within greenhouses that it leads to premature wood damage if the wood is not appropriately chemically treated. When in stock, CatchSunlight offers both square and round galvanized steel tubing that is only about twice the cost of pressure treated wood. CatchSunlight has made the sad mistake of building beautiful greenhouses using natural wood and then seeing the paint peel and the wood get damaged. It's very disheartening. Make sure excellent surface coatings are used or use ground-contact pressure treated wood. Even cedar will rot in several years, making it a less-desirable solution for the structure. Few contractors fully understand that paint and stain coatings for humid environments are a lot more expensive than is typically forecasted during construction quotes. You can estimate that appropriate surface coatings for wood protection can run on the order of $1.00 per square foot of greenhouse space. Here is an example of a wooden framed greenhouse CatchSunlight built that used discarded wood and was constructed as inexpensively as possible. You can typically expect to pay about $10 a square foot to build a wood framed greenhouse even with cull wood for the frame.
  
  
• Question: Do you recommend the Harbor Freight greenhouses?
• Answer: Yes. You can get 120 ft² for $850 plus tax (Feb 2022 price). Of course, there is a reason that 42% of the reviews are one star with comments such as, "worst decision of my life." These greenhouses use 4 mm 2-layer glazing, which is not horrible, but provides 54% less insulation value than the 4-layer 8 mm glazing. The major problem is that the design will blow over with minimal wind, so additional reinforcing is an absolute requirement for areas such as the intermountain west. If you are willing to put in a few days of work and a few hundered dollars in additional stiffening materials, this greenhouse is dynamite for the cost.
  
  
• Question: I've found glazing for the same price on Amazon after shipping is calculated. You claim to be the cheapest in the USA. Is that misleading?
• Answer: You can find small pieces of multi-panel polycarbonate for about the same price on Amazon. Typically, the small panels being offered are around 8-12 ft² each. Those small pieces are easy to handle, store and ship, making their prices seem cheaper upfront. Keep in mind that you will have to do something with all the seams using those small pieces of glazing, making your final cost much more expensive than if you used a large panel. We are the lowest cost providers of large polycarbonate panels in the intermountain region when shipping is taken into account. People have come from as far away as Texas to purchase from us as our costs are usually 1/2 of what other suppliers offer. This is because we have inexpensive infrastructure, we sell directly from our farm, we have no overhead, and our profit margins are small. We are the regional distributor for Polyvalley.com and benefit from bulk purchases. We are very interested to know of other suppliers that can provide greenhouse panels for less, as CatchSunlight would like to know their secret.

Contact CatchSunlight

• Tel: 208-520-4625

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