Build your Own Green House: Materials

by Murray Anderson

For the ardent gardener, owning your own greenhouse is a dream come true. Tropical plants can be grown all year, seeds can be started in the middle of winter and best of all there is no end to 'gardening season” the rest of the world has to put up with. However, while many gardeners dream of having their own greenhouse, only a select few ever actually achieve their dream and that's a pity since while building their own greenhouse is a significant amount of work, it isn't beyond the skills of many DIY'ers. If having your own greenhouse is one of your dreams, here's some thoughts on how you can actually achieve your goal.

What materials should you use in your greenhouse?

Strong greenhouses are built using galvanized steel, aluminum or wood framing. A less expensive alternative plastic (PVC) pipes often can't provide the structural strength to stand up against wind and snow loads.
There are a wide range of possible covering materials including glass, rigid fiberglass (plexiglass), double wall plastics or plastic film.
Glass is the traditional greenhouse covering and it has the advantages of looking good and being easy to maintain. However, glass does break easily and initially it's relatively expensive to install (although it may be possible to lower costs by using recycled glass - from storm doors for example). As well, since glass is heavy it requires a strong frame to hold it in place.
Fiberglass has the advantages of being strong and light weight plus either clear and translucent fiberglass initially allows the same amount of light penetration as glass. However, over time (10 to 15 years) the surface layer often degrades, allowing dirt to build up that blocks light penetration.
Rigid, double layer acrylic plastic or polycarbonate sheets make a great greenhouse covering. The double layer plastic sheets provide good light penetrations plus better insulation than glass or fiberglass so they can help minimize heating costs in cold weather climates.
Thin plastic sheets are available in a number of different grades (thicknesses) and they're light and inexpensive to install. Light penetration of all grades is similar to glass, however, no plastic sheets will last as long as the other options. For example, PVC film has a life expectancy of about five years.

Climate control in your greenhouse

Greenhouses need air circulation, ventilation, humidity control and heaters. Options for heating include propane, natural gas, oil and electricity. Your choice should depend on what is most readily available in your area and which is the most cost effective in your situation. (Electricity is a popular choice since it doesn't require venting but keep in mind in mind while electricity is efficient a power outage will mean your plants will be left in the cold).
Vents near the top of your greenhouse and fans to circulate the inside air are a requirement - both for cooling in the summer and for heat distribution in the winter. Since temperatures inside the greenhouse can be extreme in the middle of summer and winter, it's necessary to keep the air circulating so the temperatures remain relatively stable, rather than having the cold air near the bottom and the hot air up near the top.

A couple of final thoughts

Before starting to build your new greenhouse check with your local authorities to find out if you need a building permit. Also, ask your local utilities to mark their facilities before you do any digging on your foundation.
inally, don't make this mistake - be sure the door to your greenhouse is wide enough to allow your wheelbarrow to pass through.

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