Pit greenhouse with ICF walls

happydog · February 15, 2016

What I wanted was a simple, cheap walipini, so I dug a pit into a clay slope, 6' deep on the south side, and 10' deep on the north. Then dh's engineer friend got involved and insisted it would cave in because of lateral thrust. After much discussion they decided to line it with ICF forms leftover from our home construction. Then they poured concrete in the forms.

So the greenhouse walls are gray styrofoam encasing 8" of solid concrete all around. It's topped with poly carbonate panels secured with hurricane clips. It's ridiculously over engineered, and hideously ugly inside and out, but by George it's sturdy, lol.

My question is, should I peel off the styrofoam on the back wall to expose the concrete so it can absorb the heat from the sun? And then paint the concrete black? Or should I line the Styrofoam with something shiny like those space age mylar space blankets?

It's in zone 7a, in the mountains. It's cold at night, but most days are sunny. It overheats in summer and has to be covered with shade cloth. But in winter it stays above freezing.

This is the only photo I have of it, but you can see what it looks like. It's sleeting now or I'd go down and get a photo of the inside.
Phooey, I can't get the photo to show. The web address is www.pinterest.com/pin/14144186308890899/

Cole_Robbie · February 15, 2016

My question is, should I peel off the styrofoam on the back wall to expose the concrete so it can absorb the heat from the sun? And then paint the concrete black? Or should I line the Styrofoam with something shiny like those space age mylar space blankets?

It depends on if you need more light or not. Mylar is a waste of money, by the way, at least in my opinion. Flat white latex paint does just as good of a job for a fraction of the cost, and it's a heck of a lot easier to deal with.

Ideally, everything in a greenhouse should be either white or black. White reflects and diffuses light. Black absorbs light, and thus absorbs heat.

February 15, 2016	#1
happydog Tomatovillian™ Join Date: Jan 2009 Location: Appalachian Mountains NC Posts: 151	Pit greenhouse with ICF walls What I wanted was a simple, cheap walipini, so I dug a pit into a clay slope, 6' deep on the south side, and 10' deep on the north. Then dh's engineer friend got involved and insisted it would cave in because of lateral thrust. After much discussion they decided to line it with ICF forms leftover from our home construction. Then they poured concrete in the forms. So the greenhouse walls are gray styrofoam encasing 8" of solid concrete all around. It's topped with poly carbonate panels secured with hurricane clips. It's ridiculously over engineered, and hideously ugly inside and out, but by George it's sturdy, lol. My question is, should I peel off the styrofoam on the back wall to expose the concrete so it can absorb the heat from the sun? And then paint the concrete black? Or should I line the Styrofoam with something shiny like those space age mylar space blankets? It's in zone 7a, in the mountains. It's cold at night, but most days are sunny. It overheats in summer and has to be covered with shade cloth. But in winter it stays above freezing. This is the only photo I have of it, but you can see what it looks like. It's sleeting now or I'd go down and get a photo of the inside. Phooey, I can't get the photo to show. The web address is www.pinterest.com/pin/14144186308890899/ Last edited by happydog; February 15, 2016 at 01:26 PM. Reason: photo

February 15, 2016	#2
Cole_Robbie Tomatovillian™ Join Date: Jun 2012 Location: Illinois, zone 6 Posts: 8,407	My question is, should I peel off the styrofoam on the back wall to expose the concrete so it can absorb the heat from the sun? And then paint the concrete black? Or should I line the Styrofoam with something shiny like those space age mylar space blankets? It depends on if you need more light or not. Mylar is a waste of money, by the way, at least in my opinion. Flat white latex paint does just as good of a job for a fraction of the cost, and it's a heck of a lot easier to deal with. Ideally, everything in a greenhouse should be either white or black. White reflects and diffuses light. Black absorbs light, and thus absorbs heat.