Build a Greenhouse: The Amazing, Low-cost, Multipurpose, Solar-heated Greenhouse/Guest House

For less than $4,000, you can build a greenhouse on this 240-square-foot plan that will also serve as a small, comfortable guest house.

  • Build a greenhouse
    This greenhouse was designed to be used as a guest house or studio.
  • build a greenhouse - Solar studio diagram
    Depending on the materials you have for your greenhouse, the design will change slightly.
  • build a greenhouse - Solar greenhouse roof
    The roof was lifted into place with a boom truck. Note the ridge vents saddles of 2-by-4s. The metal has not yet been attached.
  • build a greenhouse - Greenhouse loft
    The loft is the length of the building. The open side faces south.

  • Build a greenhouse
  • build a greenhouse - Solar studio diagram
  • build a greenhouse - Solar greenhouse roof
  • build a greenhouse - Greenhouse loft

The idea behind my greenhouse/guest house concept is to build a greenhouse that has everything you need to live, and not a centimeter to waste. But you don’t have to use it as a greenhouse. It can be a guest house or an energy-efficient small home. The design is flexible, so you can incorporate whatever recycled materials you can find. Even if you buy some of the materials and hire a bit of help, you can build a greenhouse for about $3,800.

If you plan to use the building as a greenhouse, use insulated, wood-framed windows that aren’t coated with low-e or solar film, because the coating limits heat gain. Adequate thermal mass and a well-insulated floor and walls are necessary to store enough heat for a couple of days without sun. Thermal mass, such as concrete, brick or stone, helps moderate heat, tempering the thermal swings throughout the day and night.

To make a guest house, include a loft large enough for a double bed upstairs — the warmest part of the building — for cozy winter nights. In summer, the soffit design encourages airflow in the loft to keep it cool. To live totally off-grid and harvest water, install a metal roof at an angle appropriate for optimal solar performance for your area. To find this information, go to the Astronomical Applications Department of the U.S. Naval Observatory. (Click “Data Services,” then select “Altitude and Azimuth of the Sun or Moon During One Day.”)

Because the greenhouse/guest house is so small, you shouldn’t need a building permit in most locations, but check with local authorities before you build your own greenhouse. The maximum size of a building allowed in my county without a permit is 10-by-12 feet, so the greenhouse/guest house is designed to those dimensions.

The Benefits of the Greenhouse/Guest House

  • Salvaged materials keep costs down.
  • Lots of glass on the south wall provides light and heat for a winter greenhouse and/or solar heat for living space.
  • Wide overhangs shade the south side in summer, and soffit vents provide natural cooling.
  • Inexpensive DIY solar collectors on the roof transfer heat to the radiant floor via an automotive heating core.
  • Small footprint may make this structure exempt from building codes.

How to Build Your Own Greenhouse

To build your own greenhouse, start with a level building site, but make sure the site slopes enough to drain water from the building. Then cover the area where you’ll build the greenhouse with a weed barrier and gravel.

Make a 10-foot-by-12-foot grid (on center) of concrete deck pads — three rows of four pads. Put a 10-foot rot-resistant 2-by-4 (flat, not on edge) on the short rows. If you don’t plan to move the building, instead of deck pads use permanent concrete piers that are deeper than the frost line. After building the greenhouse, I moved it onto concrete barriers (used to divide traffic during road construction) and attached the greenhouse to them with hurricane clips, wedge anchors and 2-by-4s.

Deanna Berman
1/1/2010 1:26:53 PM

Hi I have an 8 foot children's playhouse and I would love to convert it to a solar/passive solar greenhouse. I would love some advice from the author of "Build a Greenhouse: The Amazing, Low-cost, Multipurpose, Solar-heated Greenhouse/Guesthouse" Thank you Deanna Berman, ND Ecovillage at Ithaca Ithaca, NY

Subscribe Today - Pay Now & Save 64% Off the Cover Price

50 Years of Money-Saving Tips!

Mother Earth NewsAt MOTHER EARTH NEWS for 50 years and counting, we are dedicated to conserving our planet's natural resources while helping you conserve your financial resources. You'll find tips for slashing heating bills, growing fresh, natural produce at home, and more. That's why we want you to save money and trees by subscribing through our earth-friendly automatic renewal savings plan. By paying with a credit card, you save an additional $5 and get 6 issues of MOTHER EARTH NEWS for only $12.95 (USA only).

You may also use the Bill Me option and pay $17.95 for 6 issues.

Canadian Subscribers - Click Here
International Subscribers - Click Here
Canadian subscriptions: 1 year (includes postage & GST).

Facebook Pinterest Instagram YouTube Twitter flipboard

Free Product Information Classifieds Newsletters