Friday, March 5, 2010

Building a Straw Bale Greenhouse: Phase 5 by Gardener Cumax

After the roof and side walls were up, we got snow again. I put my remote thermometer out in the greenhouse and it was no warmer than the outside. It made me think I made a wrong choice of roof material, but I brushed that concern aside and got busy with filling in that ridiculously ugly gap between the RBA and sill plate. I filled that gaping maw with a combination of insulation foam and spray foam. It's uglier than ever because the foam expands over several hours. That's a good thing because every single little crack needs to go bye bye.

After 3 days with the insulation in place, the greenhouse was no warmer at night. So I sighed and cussed while hacking away at 16' of 8" thick ice block that lined the south interior walls of the greenhouse. This is where the sun hasn't shined in months, and where the snow turned into ice. If there were a prison rock pile on a comet, this would be exactly what it would be like.

On Sunday the 14th I created and installed my own door into the door frame. Glenn had built a bomber-perfecto plumb door jamb. Saturday, February 20th I went in and noticed that the dirt was thawing. I moved the last 8' of ice block out without so much a "golly- darn". The greenhouse hadn't seen much sun at all, so I'm confident that the ice was keeping the temps down.

Today, February 21st, was the first day that there wasn't any ice inside. Nor was the sun shining at any point. The temps have been a full 20 degrees warmer inside than out in spite of a heavy layer of frosted condensation. We had a brief, barely-visible sun for 20 minutes and that was shockingly effective for 12 more degrees of warming! As soon as the snow resumed the temps dropped back down by 10 degrees. The frosted condensation is building up again this afternoon.

As soon as the sun can shine I will leave the door open and plug in the fan to try to ventilate that evaporative moisture out so that the film can stop radiant cooling and start retaining heat.

Because the temps are 20 degrees cooler than normal I've delayed veggie seed planting by a month. I feel like there is nothing to be gained when the temps are what they are. And because clay soil holds moisture like nothing else, I think it will take 10 solid days of sunshine to heat and evaporate that moisture away so the dry soil can start retaining the warmth that the warm veggie seedlings will need in order to sprout and grow hardy for sales in mid-May to June.

That's the plan anyways, weather withstanding.