Cost to Build
- The Passive Solar Greenhouse is a free-standing insulated building
on an insulated foundation, that-if built according to the specifications
in the blueprint-will last at least 30 years with minimal regular
- The whole building is 515.5 square feet; the interior is 350 square
feet. Another 80.5 square feet is the foundation and pad for the cistern.
- The cost to build the passive solar greenhouse cannot be stated
exactly because it is not a kit that can be shipped to your home.
- Building materials are more expensive in some parts of the country
than others, and many factors affect cost including time of year,
whether the materials are new or salvaged, access to urban or wholesale
markets, and choices about grades and kinds of wood.
- Labor costs will also differ based upon both the skills of the
owner/builder and the hourly rates for skilled and semi-skilled workers.
The Passive Solar Greenhouse is comprised of the following specifications:
- Foundation: concrete footer with a 2.5 foot insulated foundation,
two feet of which is below grade (underground).
- North wall: six feet concrete slab, strawbale wall, post and beam
frame and stuccoed inside and outside with two coats of cement stucco;
R value over 40.
- Side walls: conventionally framed with both fiberglass and radiant
barrier insulation to equal approximately R23, with a sealed three-quarter
inch COX plywood exterior and stucco interior.
- Glazing wall: redwood 4"x4" x, 2"x4" inch purlins, R23 insulated
knee wall, and 4x10' panels of twinwall polycarbonate in an aluminum
- Roof: conventionally framed with 2"x8" rafters, both fiberglass
and radiant barrier insulation to equal approximately R33, fully decked
roof with five-eights" wafer board 15lb. pound paper and 30 year metal
roofing, plus two gutters.
- Two screen doors, two solid wood doors, two large manually operated
vents, one solar powered vent, one solar powered 16 inch fan, three
small solar fans, one 10-watt (12 volt) solar panel and two solar
panels providing 42 watts at 24 volts.
- 90 metal and 90 plastic five gallon buckets to hold 900 gallon
- An insulated 1,225 gallon black FDA approved plastic cistern with
fully insulated spigot, all sitting on its own cinder block and treated
- Total materials cost is approximately $8,150 US or $7,000 without
the solar fans and panels, cistern, spigot and the cistern foundation/pad.
- When I began this project I was basically unskilled. The building
process taught me how to read a blueprint, how to do basic carpentry,
and how to be an owner/builder, where you are the general contractor.
- In calculating the labor costs, I am assuming one owner/builder,
one journeyman grade carpenter, one part-time skilled helper, and
one part-time semi-skilled helper.
- The total approximate labor cost is $6,150 US or $5,600 without
the solar and cistern installation.
- This whole project was a bit of a neighborhood sensation! I received
many hours of help from friends and neighbors, especially in the pouring
of the foundation. Other people traded their labor, with the end result
being that I actually spent only about half the labor cost in cash.
I also became well-acquainted with several teenagers in the area who
were often my helpers, learning along with me.
- These labor figures do not include the time or cost of preparing
the beds, planting the seeds, or doing all the research. Much of those
costs were met by a small USDA SARE (Sustainable Agriculture Research
and Education) grant.
- Another greenhouse of this design has been completed;
it has an adobe instead of straw bale wall. Another person plans to
use Rastra ™ Block. The design is flexible enough for your