Things to Consider When Building Your Own Greenhouse

Things to Consider When Building Your Own Greenhouse

Freestanding or perhaps Attached
A freestanding greenhouse can be an excellent chance to make a totally new space with few restrictions. My Phoenix greenhouse at CRMPI is definitely a great example of using design flexibility to really pick and choose details from the ground up, offering perhaps greater potential for high-end performance.

Nevertheless, the costs inherent in building a heavily insulated north wall can be considerable. It does not make much sense to create a small freestanding greenhouse for this reason; they are likely to be inefficient and overbuilt unless of adequate size. I recommend minimum dimensions of twelve × thirty feet. Additionally, it’s a lot more likely to need backup heat without an attached structure, based on the climate zone step you would like to achieve.

The attached greenhouses offer an oasis right off of the house of yours, an additional living space through the winter, shared heating, and reduced construction costs due to a preexisting north wall. They may be any size, and they do not necessitate the extra paths and infrastructure that a distinct structure would. At the same time, an attached greenhouse will almost certainly obstruct the outside view and, without a screen door, can introduce insects to the home yours. They carry a little risk of unwanted humidity without a sliding proper ventilation and glass door. Additionally, the design will be bounded by the home’s preexisting conditions that you want to retrofit.

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In North America, the optimal orientation for a greenhouse is usually directly south or even southeast because, in cold climates, it is important to catch the early morning sun. An east-facing orientation can do the job as well, particularly if there’s some glazing with southern exposure. In most situations, western orientation or perhaps exposure should stay away from due to overheating.

These recommendations, by the way, should be understood to be guidelines, not hard and fast rules; it is important to scrutinize your situation. In regions in which it is cloudy for most of the winter, such as the Northwest, orientation is less important because the cloud cover diffuses sunlight over the whole sky. Additionally, at higher latitudes, the summer sun moves much farther north.

Length-Width Proportions
A greenhouse that is actually shorter than it’s wide does not have as long a window for a solar gain during the day. At CRMPI, my Mana greenhouse is actually twenty-four × thirty-five feet and tends not to perform, and the seventy-six × twenty-six-foot dimensions of Phoenix. This difference is simply because the sun has a great deal more time in the day to heat space with a long east-west axis. It is a critical consideration in case you are building a freestanding greenhouse.

A great rule is actually a 3:1 size ratio.

There are various materials and methods for building foundations, and you can use any that apply to building some other structures to a greenhouse. At CRMPI, the most recent foundations I have used have been concrete piers (see image below) tied together with the structure’s framing. 2 earlier greenhouses here used sunken pressure treated wooden posts for foundation footers.

It is effortless to overbuild greenhouse foundations since they’re just holding up glazing and occasional snow loads, but depending on your area’s engineering regulations and the approach of yours permitting, the options yours might be limited. Liability concerns also can be a factor in a school or perhaps the business environment.

Roof Slope
Though Phoenix’s roof has a slope of 4/12 (falling four inches for each foot of length), at EcoSystems Design, we usually plan for a 6/12 slope to shed heavy snow loads based on the climate the region. Because the greenhouse is actually warmer compared to the outside air, a snowmelt level often forms between polycarbonate glazing and snow, helping the roof to shed some snow of significant weight. Snow is likely to stick more to double-inflated poly.

Related to the roof slope is actually the freeboard, the area between probably the lowest point of the ground and the roof. In areas with heavy snow, at least three or perhaps four feet is actually good to have so that snow will not pile back up onto the greenhouse roof or perhaps obstruct some vents.

Glazing and framing Materials

The 2 most common framing materials are metal and wood. Wood is actually excellent for smaller greenhouses and has the benefit of being a cheaper, familiar material that is actually easier to work, with or perhaps with no specialized tools. Salvaged, rough sawn, or perhaps beetle-kill lumber is readily available. Wood requires greater upkeep; although based on lumber, it can easily last 50 years in a dry climate with the right paint and maintenance.

These days, almost all commercial greenhouses are actually made with galvanized steel, often created to be attached in a long series. Kit greenhouses are most frequently made of steel, and the included instructions and fasteners can make assembly quite easy. Galvanized steel has a much longer life span than wood and does not require staining, sealing, or perhaps much maintenance. As shown by Phoenix’s roof slope, steel framing often offers less flexibility in construction, particularly when salvaged from other projects.

Glazing options are continually evolving. Six-mm double inflated poly is going to be cheaper, more flexible, and less insulating. Simultaneously, more expensive, rigid polycarbonate panels tend to last longer and hold up much better against the snow. Double-inflated poly was an excellent cheaper option in the early years at CRMPI, and it continues to work well on the roof of several of the greenhouses of ours.

Glass could be suitable for southern or eastern walls, but it must be used solely for vertical glazing due to its considerable weight. Mounting problems can happen due to contraction and expansion, and glass offers a much larger issue than plastic or polycarbonate if it breaks. It’s usually more costly and less insulating than polycarbonate and will also tend to intensify direct sunlight, which may burn plants in some cases.


Insulation is important on the north wall and the west wall; make sure to insulate all of the walls you don’t have glazing on. Foam insulation or perhaps structural insulated panels (SIPs) work well but have to be sealed and kept dry – they are not rated for the humidity in a greenhouse. I used these panels when constructing Phoenix, but commercially we have started to use metal siding directly against the Styrofoam on the SIP interior to eliminate some wood product. There is a wide range of room to implement your own preferred method here. Straw bales are actually a popular natural building method but probably not a great idea for use in a greenhouse due to the potential for mold problems in a high humidity environment.

Beds and Paths People generally want to install large paths to accommodate carts and wheelbarrows, but think carefully about how you are likely to be using the greenhouse of yours.

Following the first construction and bed preparation, there is not much need to bring a lot of material in and out. Here at CRMPI, I tend to build smaller pathways to maximize growing space, and I have a big staging area near the door to bring materials and mulch in with fifteen-gallon nursery pots.

Each greenhouse creates a new macroclimate inside it, but within that might be a selection of microclimates. These will be created by the design of yours and the materials used and may change over time with the addition of thermal mass by water tanks, more plant biomass, or perhaps new infrastructure.

While the greenhouse climate will be mostly homogenous, it is essential to identify existing microclimates to help establish thriving plant communities.
For example, cold air sinks, so if your greenhouse has 2 levels or perhaps slopes, probably the lowest path will be a cold sink, and the outside edges of the space will be colder in the winter in which they lose heat to the outside. By installing circulating fans, you can help mitigate the issue. The southwest corner will probably be the hottest and sunniest quadrant of the greenhouse since it gets the most sun exposure. The northeast will be cooler and is a great spot for a propagation table or perhaps a washing station. Bear in mind the way plant growth will create shady zones over time, and plan for your tallest perennials in the northwest, often the tallest point of the greenhouse.