Greenhouse Heat-sink Question

Greetings ~

I've never lived in a zone where I needed a greenhouse before. I'm going into transplant shock :-) I know you can use stone and masonry to absorb heat, and also barrels of water painted black. I've just moved to 4.7 acres of - sand - in zone 6b. I don't know if we'll be able to put in a greenhouse this winter, but by golly, by next winter, we will definately have one! My question is this - If we build the outside and inside walls with fiber-cement board or something similar, painted it black, and filled it with packed sand, would it accomplish the same thing? It sounds like it should. And if I covered the outside with morning glories in the summer, seems like the sand insulation would keep it cool? I mean, with sand at least 5 feet deep, I'm trying to come up with as many creative things to do with it as I can.

Thanks a bunch!

I'm not exactly clear about the idea, but I believe you are thinking of parallel, cement board sheathed walls 5 foot apart and filled with sand? If that's the idea, make sure your framing is extremely well constructed and studs are not on the sand side of the wall but on the outside of the cement sheathing, pushing it back against the sand.. A wall of sand 5 feet thick is going to exert a huge pressure on the cement board, which is not a very strong material when asked to resist lateral forces. Foundations are engineered using this material though, usually with a minimum of 2x8 pressure treated studs at 16" o.c. so it can be done. Plans should be reviewed with an engineer though for your own safety.

If you can make the walls sufficiently strong and provide summer shade, cooling likely will be adequate though up here in the northern mountains, my concerns are more on the absorption and retention of heat, and less on cooling.

Wayne

Thanks for the info. I was thinking mor along the lines of 2 foot hollow area between the wall front and back, filled with sand, about 3 foot tall. The polycarbonate area of the green house then extending up another 3 feet. Just trying to come up with ideas for later.
Thanks a bunch! Karla

Hmm....sounds like it might work pretty good to me, using your 2 ft thick walls more as foundation walls, with the rest of the g-house fitted on the top!

(And by the way...Howdy Kmom...ain't seen you around much lately! Good to see ya again! :>)

The g-house walls you're describing sound to me like it would be pretty much the same as a "dugout" greenhouse...one that is dug into the ground for temp extreme protection. Basically what you'd be doing is bringing the ground level upwards and hopefully creating the same environment.

This would be interesting to see come to fruition. And the best part about it that I like (being the miser that I am!) is you have ample sand to work with! Yay!

Shoe.

Greetings ~ Thank you ~ Good to be back ~ We thought about digging down into the sand, but even with the help of a cute blue tractor, everything just caves in. Maybe dig & shore up the walls as we go down? I think insulation down under would be better, with just the top 3 ft with the polycarb peeking out, but the whole sand thing continues to be an engineering challenge. Pond digging may also prove to be quite a challenge!

Have you thought of building a reinforced cement block innerwall then raising a berm around this wall. Much like a retaining wall. Then placing the polycarbonate on top of that.

Much of our property is sandy loam so many of my problems revolve around keeping plants' roots humid. Fortunately, we have a few patches of clay soil and that's where our stock ponds are located. I once saw a program on PBS of people trying to build on sand. They used water, pouring small amounts in the area to be dug. Wet sand sticks together long enough to be dug out in stages. It also remained wet long enough to place the posts in the ground. Maybe this would work for you.

Thanks for the ideas on the GH. We're just sandy-sand, and I am also seeing that we will have problems with humidity for the roots, leaves and everything else, including for the humans!

Also, going to use your idea about "water-dig-water-dig" for putting out fence posts in the sand next weekend. Very un-scientific test with a trowel and a glass of water seems to indicate that this may be a viable method.

Thanks, everyone!