The concept for our greenhouse originates with Carol Ford’s book “The Northlands Winter Greenhouse Manual“. We also incorporated some designs from Paradox Farm. I highly recommend the book if you are interested in building a deep winter greenhouse
We started with some excavating and sinking posts into the ground.
The greenhouse is attached to our wood shed and you can see the boiler pipes coming out the side of the shed. We could not go deeper in the ground without moving the wood boiler pipes.
We boxed in the area that will hold the thermal mass (rocks). The bottom layer of our thermal mass is salvaged concrete pieces from an old silo. This ended up working well since we were able to drive on it with our bobcat without causing ruts in the dirt.
We lined the inside of the rock bed with insulation and on the outside of the rock bed we added insulation at a 45 degree angle. The drain tile is perforated and is meant to channel hot air through the rock bed.
We were able to use the bobcat to move the rock into place. We used 1.5″ washed rock. The bobcat saved hours of work! We used bracing to keep the posts from moving while the rocks were being added. We ended up with about 14″ of rock on top of the concrete from the silo.
All the rocks are finally in place and we closed up the perimeter. The black pipe sticking up will eventually tie in with a pipe collecting hot air in the peak of the greenhouse.
We covered the rock with landscape fabric and then added dirt to finish the floor. Now we are ready to start on the walls.
The first wall to go up was against the wood shed. We used 2X6 lumber to build a 12′ wall. Part of the reason for the 2X6 construction was to facilitate using wall insulation that we already had on hand. We have posts going up to support the peak of the greenhouse which is at 14′.
It was really fun (NOT) adding the boards that run along the peak. We placed two 2X10 boards running along the peak which support the roof. The boards on the angle are 2X6 which will support the polycarbonate panels.
By the end of the day we had the roof framed and ready for metal sheeting. We used 2X6 boards with 2X4 purlins on top.
We extended the wood shed roof to make a walkway into the greenhouse that is sheltered. We are ready to sheet the walls!
Enclosing the greenhouse with OSB.
We were able to re-purpose insulation from another building. All the insulation in the walls is 6″ with 12″ in the ceiling.
We decided to sheet the ceiling with white metal sheeting due to the moisture that we expect in the greenhouse.
We special ordered the polycarbonate sheets so we could get 10mm 6X12 sheets. We have 4 sheets on the long angled side.
Whew! Twenty-one days ago this spot was fenced in for critters.