Bryan & Lois Pratt built this incredible high-altitude greenhouse in Colorado.  They give the details in their own words.  If you look carefully you will see a twelve-sided, two-story cordwood home on the right.

“We built the greenhouse the summer of 2008 and Lois was literally planting under Bryan working on a ladder trying to complete it. Lois was determined to get a fall crop in and the cutoff for planting, in order for good root establishment before shorter days, was September 15th. Lois wanted to experiment with the cold weather season. In the photos below, you can see the pieces Bryan put in place for what is called a “subterranean heating system”. We excavated an extra two feet of dirt, cut holes in two 55-gallon plastic drums to accommodate 4-inch french drain pipe, a bunch of them, and laid this perforated pipe along where all the growing beds would be then buried two layers of these pipes.”

“Blowers (fans salvaged from old forced hot air heating systems) were to be placed on top of the blue barrels to move the daytime sun-heated air down from the greenhouse through these tubes to store the heat in the dirt, charging up its thermal mass. We also found and placed fifteen 55-gallon black metal barrels, filled with water, along the north inside wall of the greenhouse which act as additional thermal mass storage, storing the day’s heat and slowly releasing this heat at night. We are also using an automatic (wax-filed piston) vent opening device to add venting to the greenhouse. For the greenhouse covering we used Solexx™. Solexx™ is a unique twin-wall greenhouse covering material. Solexx™ comes in rolls and can be shipped in. Other greenhouse covering products come as flat panels and must be freighted in. Check these costs in your area.”

The foundation is below grade and allows for the temperature to be moderated.

Some delightful pictures of the interior during the growing season.

If you have not read elsewhere on this website we are located at an altitude of almost 9500′ in the Colorado Rocky Mountains. Having fresh greens to eat in the winter without traveling to the store can be a challenge… but to our surprise, this ‘challenge’ is not a roadblock. Incorporating a subterranean heating system into our high-altitude greenhouse has been a wonderful success.

The beautiful greenhouse (below) is made to withstand the cold climate in Maine (USA).  With rock on the bottom, cordwood in the middle, and board and batten on the top, the structure provides enough thermal mass to extend the growing season at each end of the season.

This beauty was built by Ethan Adolphsen and is a testament to his building skill.

The arched doorway is a lovely addition to the building.  The planting will be done on tables with trays.

Large double-hung windows on each side provide cross ventilation which helps keep the plants healthy.

Should you wish to learn how to build a cordwood cottage, cabin, or home, please visit   While you are there, click on the pictures, read the brief articles, check out the latest workshops and newsletter and if you are interested click on the Online Bookstore to see all the cordwood literature available in print and ebook format.

If you have questions that aren’t answered on the website you can email me at  

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Readers have requested a brief bio, so here goes:

“Richard & Becky Flatau built their mortgage-free cordwood home in 1979 in Merrill, Wisconsin. Since then, they have written books, conducted workshops, facilitated the 2005,  2011 and 2015 Cordwood Conferences and provided detailed consultation for cordwood builders.  Cordwood Construction: Best Practices DVD 2019,  Cordwood Construction Best Practices 2020 (print), Cordwood Conference Papers 2015 and Cordwood House Plans 2021 ($15) with 16 different floor plans, are the newest publications available from their online cordwood bookstore.”


To learn how to build your own Mortgage-Free cordwood home visit