Greenhouses What are they?.
Choosing what materials to use in constructing your greenhouse will have multiple effects on its usefulness. The same holds true for those considering purchasing a pre-made greenhouse.
The first consideration is, of course, the roof material. The largest percentage of highest intensity sunshine comes during the late morning through early afternoon hours when the light strikes the roof. There are several choices for material and design that can affect how much of that sunlight energy enters your greenhouse.
Glass is traditionally one of the more popular choices. It transmits light well, it's relatively easy to clean and it has excellent reflective properties that hold in the heat produced.
But glass is transparent, heavy, can be expensive and subject to breaking. Extreme temperature differences inside and out can cause spontaneous cracking. Accidentally bumping the glass can cause it to shatter.
As a consequence, and as the result of advances in materials over the last 20 years or so, many more greenhouses use plastic and composites for the roof. Plastics can be purchased that are completely transparent or only partly so, i.e. translucent. That helps control the amount of sunshine - helpful in climates that have long, summer hours of direct light and less cold winters.
Glass is still an option for those who want to invest in some system for shading the roof and several choices are available. There are inexpensive mechanical systems that use white cloth, bamboo, plastic shutters and others. For those with some money to spend, there are even systems that will sense the amount of sunlight entering and electrically open and close the shades!
Walls are the next major consideration. Here again, many are the traditional glass. When selected, they offer the same advantages and challenges as the roof, with the added proviso that they have to bear the weight of the roof. Most are embedded or alternated with some kind of load bearing rods, beams or other support materials.
A glass greenhouse can be a beauty to behold, but modern plastics and composites can also provide a lightweight, strong and attractive alternative. Some are even partially wood, aluminum and other materials, though these are more often used only on the lower half. There's little point in building a greenhouse that doesn't admit light - that's just a shed!
Picking a material for the floor requires some thought, too. Wooden floors are inexpensive to build and replace as needed. But they don't have the temperature control features offered by cement which traps heat and re-radiates it later in the day as the temperature cools. Choose something that offers good drainage and will last through several winters.
When choosing materials consider sunlight and heat control, the needs of the type of plants you intend to house and your own comfort. You'll want something you can enjoy spending hours a day inside.