Monday, April 13, 2015

My Greenhouse

My greenhouse. First introduced in my Spring Update post, March 29, 2015; which the City of Minneapolis, Inspections, is calling an illegal addition, because I did not consult the city, not applying for the requisite permits.

This was the first stage, started early last spring 2014.

The roof and east, south and southeast walls were enclosed with glass, and rigid acrylic, the west wall remained open through the summer.

Spring 2014 plant starts.

This picture shows distinctly the two different stages (taken yesterday, with the pond foreground, it is early spring with little green growth outside the greenhouse.) The first stage I built with a cedar tone treated lumber, which I paid about $450 for. The second stage frame is reclaimed old-growth Douglas Fir, I removed from a house near Lake of the Isles, when I was in remodelling during the housing bubble, 2004-2007. The glass is mostly reclaimed sliding glass doors, I have collected through Craigslist mostly. The bulk from one job, bartered in exchange for tearing off two layers of siding on a house, and installing some windows and doors. I spent about $1000 to build this. I wish now I had used reclaimed Douglas Fir for the entire frame, as I have enough. A 155 sq ft glass greenhouse for $500 approx?

The roof is constructed with 2x4, with a 1/4in spacing between joists, greater than the width of the glass sheets; with 2x2 (or equivalent) screwed to each side of the inner joists, the glass is resting on. I used carpet tape and foam sill seal as waterproofing, between the glass frame and the joist. The upper level glass is laying horizontally across the joists, overlapping the glass below like a shingle. As you can see, the dimensions are dictated by the glass; that sheet of glass in the upper left (northwest) corner is from a window that had the right width to fill the space, but was longer than the sliding glass sheet next to it. 

For the walls, I left the sliding glass doors in their frames, inserting them into custom pockets of 2x4 framing (the roof glass, I removed from their frames.) Normally in stick-frame construction, you would rest the joists directly above each wall stud. But because there is a roof overhang on each end, the spacing doesn't match up, dictated as it is by the glass dimensions. No matter, the roof load is not significant, even with heavy snow. The roof pitch is about 22.2 degrees. I would have raised it higher to put less downward stress on the glass, but the angle was mostly dictated by the roof line above the sunroom/front entry. 

The greenhouse is not attached to the house in any way. It is one separate structure effectively resting against the south face of the house.

The door is sliding glass I hung from hinges. In the winter I will keep it closed, seal it, and enter the greenhouse from the house, through the sunroom.

There is about a one inch gap between the roof glass and the top plate. I stuffed battened fiber glass insulation in the gap, which I can remove in the summer for venting. I once criticized (gently) a friend who used blow-in foam insulation in a project of his. Hypocrite. LOL.

Again, the greenhouse is not attached to the house, by any bolt or screw or strap etc. The gap between the house is filled with more spray foam, and some fiberglass. I filled this west wall upper corner, with plywood on both sides and a rigid foam sheet between, because I thought it would help conserve heat in the winter. But it also blocks critical late afternoon sun in the spring and fall especially, so I think I will cover it with acrylic or poly-carbonate, and build removable insulating panels I can place there in the evening in the winter.

The 2x4 + 2 2x2 joists. At the peak, there is about a 6 inch gap between the glass and the wall of the house. I covered it with two, 12in wide sheets of plywood, covered with shingles, panels I can remove in the summer for venting.

Here the two stages of greenhouse come together. I dug a trench 4.5 feet below this, deep enough to insert a 4x8 sheet of 1-1/2in rigid foam, the hole backfilled with a heavy sand mix, with a footing, class-five crushed limestone 2ft deep and 18in to 2 ft wide, the full length of the south face of the greenhouse.

2015 plant starts.

Winter Solstice, the sun is just above that chimney. There are too many trees in the way for a proper winter greenhouse, reducing it's efficiency when it needs the sun most. But alas, I am in the city, and can not go about cutting down boulevard trees. As for winter greenhouses for most of my neighbors? The Minneapolis city grid has almost every house in most neighborhoods, in the shadow of it's southern neighbor, most of the winter, spring and fall.

The view from the sunroom.

From the bedroom. The summer plants, the tomatoes and peppers and eggplant, are enclosed in a greenhouse within a greenhouse. When the day is sunny and above 40 degrees outside, I can leave the windows open and the greenhouse heats the house. Two nights ago I left the windows open, the temperature outside hit a low of 48, the thermostat set at 64, it was 74 at peak and 67 in the morning. It was 75 outside yesterday, with a normal high of 56. I propped open the greenhouse door much of the afternoon. It peaked at 76 in the house. A thunderstorm rolled through late evening, it was 58 outside at midnight, the windows were open to the greenhouse and it was 73 in the house. This morning it was 46 outside, 67 in the house, with the windows to the greenhouse open all night.

April 13, the greenhouse is considerably greener than the garden. There are plants in the ground in the greenhouse, as tall as they would be, mid-june outside. The greenhouse is a work in progress. Many changes to come, of my own design.

Minneapolis City Inspections has received hundreds, perhaps thousands of complaints about my house, mostly about the garden. They don't hear from the people who walk by and tell me how much they love my garden and greenhouse. April 15 is the deadline to file for a permit. I will go to the City Attorney, Monday, and see what the consequences are for not paying for a permit. The question is, is defying the code more or less costly, than pulling the permit and risking the Inspector requiring an expensive list of unnecessary "fixes"?


Ien in the Kootenays said...

Why in Earth's name would anyone take the trouble to complain to the village about a garden and greenhouse? Boggles the mind. Do you need to start a petition?

William H Duncan said...


I went to Inspections, talked to them, and a lawyer in the city attorney's office. It seems to be merely the grinding of the wheels of bureaucracy, and it may have stopped. I'm not sure. But if the pressure does get bad, yes, I would put the call out...Thanks for suggesting it.


Doug Lowe said...

Wow! I'm amazed at how you did that greenhouse beside your home all by yourself. That must be tough, given that you have to use sturdy materials to build it.Thank you for sharing your project with us! I'm excited to see how this will turn out. :)

Doug Lowe @ M & M Glass

William H Duncan said...


Thanks for checking in and the support. Sorry to get to your comment so late. I've been on hiatus.