Greenhouse Part I – Foundation

Last week I introduced my failed attempt at a hoop house last year and the plans to build a new greenhouse this year. After finalizing the size and layout and then finishing up the full plans for the project, I could get started once again digging a foundation. Luckily for my back, this was a much simpler foundation to dig. I began by clearing out the area that the new greenhouse would sit and then dug trenches about 4 inches deep to set the 4”x4” Pressure Treated lumber that the greenhouse frame will sit on. For each of the walls I added 2 cinder blocks set deeper down into the dirt for added stability and to help with leveling the foundation.

Halfway there. The sledgehammer was extremely helpful in tamping down the lumber to make everything level.
The cinder blocks should add a bit of stability to the foundation. They certainly made it easier to level everything.

After digging out the trenches and laying the foundation lumber in place, I was able to connect each corner using a simple L bracket. This should provide plenty of support for this simple design that will not be under high loads. In addition, after connecting each of the corners, I drilled holes through each side and drove 2’ rebar stakes through the lumber and into the ground. This added stability allowed me to make sure everything was square and will prevent any shifting in the foundation.

The rebar in place ready to be pounded in.
This lumber will eventually be covered by soil and woodchips, so we used ground contact pressure treated wood.

Laying the foundation for the new greenhouse only took about half a day of work and was pretty straightforward. Now that it is in place I can frame out the walls and stand them next weekend. Seeing the foundation in place was fantastic and confirmed to Allyson and I that this was a much better structure to have behind our house than the old shed that used to be there.

Leave a Reply