How much does it cost to build a greenhouse?

Whether you view it as a conservatory or a working greenhouse, a structure meant to provide ideal growing conditions on a year round basis is a great addition to any gardening enthusiast's home.

Is it a DIY project? Not really, the average person is not going to know how to work with the steel and glass required for completing such a project. Nor are they likely to be able to handle the yards of concrete necessary for the project too. This means that the owner will need to contact at least three different contractors and request a bid or quote for the work. Be sure that each quote includes everything from site preparation to water supplies and finishing work. In fact, it is usually best to spend the time to seek out and communicate with contractors who have already built such projects.

For the purpose of this conversation we will consider the costs and requirements for the construction of a greenhouse on a residential lot. According to the Craftsman National Building Cost Estimator program, the pricing on a greenhouse measuring 12'x12' would be around $3587, or $25 per square foot.

Cost breakdown

The costs for the project will include:

• Excavation and site preparation - costs will vary according to the level of work necessary, but all such projects would require the leveling ¹ of the site in order to receive the concrete and the drilling of a well with a 6" diameter feed and a horse power pumping mechanism (unless the pre-existing well or water supply could be easily tapped into and channeled to the greenhouse. This might be problematic in areas of heavy frost, however);

• Concrete - the knee walls and flooring of the greenhouse would demand roughly 3.5 cubic yards of concrete. This is priced at an average of $75 per cubic yard, and with labor would cost around $540;

• Materials - the greenhouse described here would demand a heavy steel frame, 8' walls constructed of multi-wall polycarbonate ² or glass, roofing vents, and electronic exhaust fans. The average pricing on a 144 square foot greenhouse using such materials is $2700;

Enhancement and improvement costs

• Heating - greenhouses located within areas that receive freezing weather might require the addition of a heating unit. These come as electric and propane ³ models, and the average price for a unit sized to meet the needs of the structure described here would be less than $250;

Remodeling Terms Cheat Sheet

³ Propane: A hydrocarbon gas used as a common fuel source