There are a variety of materials that can be used to cover a greenhouse today. With the current explosion of interest from both commercial farmers and backyard gardeners, the options for materials are constantly expanding. Greenhouse covering material includes:
- Polycarbonate (rigid panels or flexible rolls)
- Polyethylene Plastic film
- Polyethylene Panels (semi rigid panels or flexible rolls)
- Fiberglass (rigid panels or flexible rolls)
- Acrylic (rigid panels)
Since we had already decided on using PVC pipe for constructing our greenhouse, we would not be using any solid panel type material to cover the greenhouse, but we still estimate the cost to cover a small greenhouse ( 5 X 10 foot base 4 – 5 feet tall) below for each greenhouse covering material for comparison purposes. We also estimated the cost to cover a typical sized hobby greenhouse (10 x 10 foot base 8 feet tall). Keep in mind, these costs are for the covering material only. Any clamps, fasteners or furring strips would cost extra.
Glass is the Traditional “True Greenhouse” Covering Material
Glass has been the traditional greenhouse covering material. Chances are, the first glass greenhouse you saw years ago was made from hundreds of glass panels. Glass requires a very costly and sturdy structural system, but if constructed well, can last for at least 30 years and and clean glass always allows good light transmission. The main problem with glass is that is a poor insulator unless you use double or triple panes. Glass is also difficult and expensive to replace if broken.
A small A-frame greenhouse with a 5 X 10 feet base, standing only 4 – 5 feet tall would require between 114 – 137 square feet of surface area to cover. We looked up the price for two thicknesses (3/16 and 1/4 inch) for both annealed and tempered glass and found it quoted at between $5.78 to $8.44 per square foot. Even if we could find glass for $4.00 per square foot, the cost for the glass alone to cover a small greenhouse would range between $457 – $1155. The glass for a normal hobby-sized greenhouse (10 X 10 feet base; 8 feet high;420 square feet of glass) would cost between $1680 to over $3600. You can quickly see why other materials are being used to cover greenhouses.
Polycarbonate Greenhouse Panels and Rolls
Polycarbonate is a very strong and light-weight material. Panels made for outdoor use have UV treatments that help prevent yellowing and deterioration from sunlight and are guaranteed for about 10 years. Brand names of polycarbonate panels include Dynaglas, Lexan, HighLine, Sun-tuf, Tuffak and Zelux. Polycarbonate panels are available in various thicknesses from 0.03 inch (0.79mm) to 1/2 inch (12.7mm)
- Corrugated Polycarbonate Panels – rigid panels – single wall construction – cost $4.71 per linear foot (50 inches wide)
- Polycarbonate Panels – rigid panels – twin wall construction with air space in between for added insulation – cost $51 for one 4 x 8 foot panel 6mm thick
- Polycarbonate Panels – rigid panels – triple wall construction for additional insulation – cost $117 for one 4 x 8 feet panel 16mm thick
- Polycarbonate Rolls – flexible sheeting – twin wall construction with air space in between added insulation -cost $6.17 per linear foot -rolls are 49 inch wide)
The Polycarbonate prices and cost estimates have been updated. The cost for covering the very small A-Frame greenhouse is much more economical using polycarbonate panels. The cost would range between $204-$255 for 6mm twin wall panels and between$468-$555 for 16mm triple wall panels. The flexible twin wall sheeting would cost slightly about the same, but would require a solid frame centered on 49 inches. A 10 x 10 foot hobby greenhouse would cost about $1600 to cover with the 16mm triple wall panels.
Acrylic Greenhouse Coverings
Most people are familiar with acrylic skylights and other “Plexi-glass” materials – (other Brand names include: Acrylite, Lucite, Optix, Polycast and Aristech) acrylic is very strong for snow, strong winds and even hail impacts, but very specific attachment requirement due to expansion and contraction. Acrylic is also very expensive, but can last 20 years, so one manufacturer claims it is cost effective over the long run, especially in commercial greenhouses where heating costs can be reduced up to 30%. Though described as rigid panels, acrylic panels are flexible enough to be molded over shallow arcs. Acrylic panels are available in several options:
- Single Layer Acrylic Panels - Cost is about $90 for one 41 inch by 8 foot panel (corrugated clear)
- Twin Acrylic Panels – air space in between panels for insulation – Cost is about $108 for one 47.25 inch by 8 foot panel (8 mm thick)
- Triple Acrylic Panels – more air space, more insulation
- Quad Acrylic Panels – most air space, most insulation
- Non Drip Acrylic Panels – one side treated to prevent buildup of condensation, which increases light penetration and reduces damage to small plants from dripping water
- UV Blocking Acrylic Panels – to protect UV sensitive materials inside the greenhouse
The cost for covering the very small 5 x 10 foot A-Frame is with acrylic panels is about the same cost as glass. Because the single layer we found listed is made in an unusual width (41 inches), it is about the same cost as the twin acrylic panels that are produced in 47 1/4 inch widths. The cost to cover the small A-Frame would would range between $432-$540 and the cost to cover a 10 x 10 foot hobby greenhouse would be $1440 – $1512. No doubt, the triple panels, quad panels and UV blocking panels would be more expensive, but the products must be fairly new, because we could not find any online price quotes.
Polyethylene Plastic Greenhouse Coverings
As we have learned, all plastic coverings are not created equal. Choosing the Right Greenhouse film (AKA agricultural plastic, poly-film and greenhouse plastic).
- Utility Grade (4 and 6 mil) polyethylene plastic – will last one season exposed to sunlight – do not attempt to use for two seasons – available at most hardware stores – Cost for 10 x 25 ft roll is about $20.00
- UV protection – Protects plastic film from Sunlight – guaranteed to last 4 years – Cost for 12 x 25 ft = $39.00 (6mm thick)
- Thermal protection – Reflects IR back into greenhouse – claims to cut heating costs 15- 30% and to maintain higher temperatures at night if you don’t heat – Cost $92 for 12 x 55 ft
- Anti condensation – condensation attached to film can reduce sunlight, also reduces dripping onto plants
- Protection from heat – Opaque to reduce light transmission to 55% – Cost for 16 x 55 ft = $120
Polyethylene is the least expensive covering for a greenhouse. One 12 x 25 ft roll will cover the small 5 x 10 foot A-Frame two times, so it will cost about $10 to cover with utility grade plastic each year. It would cost about $39 to cover the A-Frame plastic greenhouse with UV protected polyethylene and even if it only lasted 3 years instead of 4, that would average $13 per year. The thermal rolls I was quoted are longer, so one roll would cover the A-Frame greenhouse at least three times, so $92 would last for 9 to 12 years, or $7.67 -$10.22 per year.
A 10 x 10 x 8 foot hobby polyethylene greenhouse could also be covered with one 12 x 55 ft roll of thermal protected polyethylene for about $92 and still have about 40% of the roll left over.
Polyethylene Panel Greenhouse Coverings
Polyethylene can also be made into panels, usually with a twin wall construction with air space for insulation in between – can be used to construct greenhouse as rigid panels or can be semi-flexible and be fitted to shallow arches. UV protected and some are guaranteed to last 8 years. Solexx is a brand name.
- 3 mm flexible rolls with UV protection- Costs $6 per foot for 49 inch wide panels
- 5 mm flexible rolls UV protection – Costs $8 per foot for 49 inch wide panels
The small 5 x 10 foot A-Frame would cost between about $180 and $280 to cover with flexible polyethylene panels depending upon whether we used 3 or 5 mm material and also depending upon the greenhouse being 4 or 5 feet high. That cost would average between $22.50 to $40 per year if the flexible polyethylene material would last 7 or 8 years. It would cost about $630 -$840 to cover a 10 x 10 x 8 foot hobby greenhouse.
Fiberglass Greenhouse Coverings
Fiberglass is opaque, but lets about as much light into the greenhouse as glass does, and may allow more light in when the sun is at low angles because very little light is reflected. Seems as most manufacturers offer a 10 year guarantee against yellowing and structural failure. Seems as though fiberglass panels in the past would begin to deteriorate on the top and expose fibers that would trap dirt. This would block sunlight and require washing and re-sealing.
- Rigid corrugated panels – cost $72 for one 5 oz, 52 inch x 8 ft panel
- Flexible rolls – cost $335 for 4 ft X 50 ft roll
It would require six fiberglass panels to cover the small 5 x 10 foot A-Frame greenhouse if it needed to be over 3 feet tall and would cost about $342. It would require at least 14 fiberglass panels to cover a 10 x 10 x 8 foot hobby greenhouse and cost a little more than $1000. The A-Frame greenhouse could be covered with one roll of flexible fiberglass at a cost of $335 with almost half of the roll left over. A hobby greenhouse would require three rolls of flexible fiberglass at a cost of about $1000, but would have most of one roll left over.
Vinyl Greenhouse Coverings
Vinyl covering materials are primarily for used for a clear “showroom” quality look. Users are advised by the manufacturer to use only on the ends of the greenhouse so customers could have a nice, clear view of facilities. Not intended for use as covering for the top of the greenhouse. The clear vinyl “siding” is supposed to last about 4 years and costs $130 for 54 inch by 50 ft roll of clear film 16mm thick.
We have no intention of using vinyl, but just in case someone else is interested, the cost to cover the 4 sides of a a 10 x 10 x 8 foot tall hobby greenhouse would be $280 for two 50 ft. rolls. The roof would still have to be covered with another material.
Our Choice for a first time Greenhouse Covering
Our choice for a material to cover the A-Frame hoop house (greenhouse) for the first two seasons was the simplest cheapest material. We used a utility grade (6mm) polyethylene plastic. It works well with the PVC Pipe structure and is clamped to the PVC pipe with simple homemade clamps cut from short sections of PVC pipe. If you use polyethylene plastic that is not UV treated, do not try to use it for a second season. It may look OK at the end of your first season, but it will disintegrate before you make it through the second season, and it is nearly impossible to pick up all the plastic fragments. We still plan to use the same polyethylene plastic again this year, because we still have enough left over to cover the greenhouse again. Next time, we plan on using a buy a UV and IR protected sheeting because it will be more economical and less wasteful in the long term and our tomatoes and peppers could benefit from some additional thermal help on our cold nights.
After two growing seasons, the plastic sheeting held by homemade clamps have worked very well. When fastened correctly and completely closed, the plastic sheeting has even held up to wind gusts of 70 mph, but on an other occasion, when the greenhouse was partially opened for ventilation (and only partially fastened), the plastic sheeting was blown loose by an approaching storm. The A-frame shaped hoop house also allows the plastic to shed snow without any damage.
Q: What greenhouse covering material are you considering? Please comment below. You may also want to look at our Greenhouse Building Materials page that discusses the pros and cons of different types of materials for the frame.