Building a Greenhouse – Determining Location and Constructing the Foundation

    Published: 06-16-2009
    Views: 25,771
    Paul Simon, Landscape Horticulturist with the National Gardening Association, demonstrates how to determine location and construct the foundation for your greenhouse.

    Paul Simon: Hi! I am Paul Simon, Landscape Horticulturist with the National Gardening Association and today, we're talking about how to build a small greenhouse. Now, we'll discuss locating your greenhouse and constructing the foundation.

    This depends on the type of plantings, but typically, you are going to want to locate your greenhouse so that it maximizes your sun exposure. Here we've selected an area that's relatively level. We have trees along the North side but we have plenty of sun exposure as the sun travels from East to West along the South side, we're continually getting sunlight throughout the day.

    One of the first steps before constructing your greenhouse is to contact your local municipal offices. The Planning and Zoning Department will let you know if a permit is required for the construction of the greenhouse. After we've located a preferred location, we're going to mark the corners of our greenhouse. The greenhouse we're constructing is 14-feet wide by 20-feet long. You can see the two stakes in the back, there're two in the front as well that we're going to use to mark out location of the greenhouse.

    Once we've staked the location, we're then going to want to call our local utility companies to ensure that we're not placing the greenhouse in an area where there are any existing utilities. In some locations it's 811, it's another company called Call Before You Dig or another company called Dig Safe. You're going to want to contact them and what they'll do is send a local representative out who will mark any existing utility locations to ensure that your location of the greenhouse is not going to be affecting any utilities in the area.

    To begin the foundation construction, carefully measure and then hammer 4 36-inch long rebar sections into the ground at the corner locations of the greenhouse, leaving about 10-inches of the rebar exposed at the surface. Re-measure the footprint to ensure that the placement of the rebar is exactly 14-feet wide by 20-feet long for your greenhouse.

    Continue measuring and then hammering in the remaining 36-inch long rebar sections 4-feet apart along the two longest 20-foot sides of the footprint, leaving 10-inches of rebar exposed again at the surface. In total, you'll have 12 rebar segments; 6 on each side of your greenhouse hammered in so that they're 10-inches up from grade. So that's how you locate and construct the foundation for your greenhouse. Up next, we'll talk about constructing the PVC frame.