Saturday, March 17, 2012

A Greenhouse for the backyard

A neighbor moved and the new people did not want their backyard greenhouse, so they past it on to us. This greenhouse is a light-weight aluminum frame with a bunch of glass panels. It took us about two hours to remove all the glass and move the frame from their backyard to ours.

This is apparently Model 86 "Curved Greenhouse", probably from Halls Garden Products, Ltd. Aylesford, Kent, England, originally from 2004.

The first problem was figuring where to put it. We tried moving the frame around several places in the backyard, and finally decided it should go next to the South Bed, behind the stone wall and next to the raised garden. This area is shaded by several trees, but they are deciduous so they drop their leaves in the winter and so things should be sunny in the winter and more shaded in the summer.

The next problem is setting up a foundation. Since the placement of the greenhouse is still subject to change, I decided to use a relatively temporary foundation -- a box of wooden beams. The more permanent option would be a concrete slab, but that would make it hard to move. Instead I got eight 4x6 pressure treated timbers (YellaWood) from Home Depot ($132,37). The foundation box should be 101.5 by 76 inches, and I was able to get Home Depot to cut the 8-foot timbers to the correct lengths. I assembled the foundation in the garage and used 6 inch lag screws to hold them all together.

Next I had to level the ground where the greenhouse would go. The back of the greenhouse is at ground level, so the front is below ground, about 4 inches, since the ground slopes back.

After digging it out level from front to back and side to side, I poured sand (6 bags) along the edges. The idea is that the sand is easier to shift to get the foundation box level. I took the box from the garage and re-assembled it in place.

I covered the entire inside with weed barrier, running both front to back and side to side. I filled the bottom two inches of the box with decomposed granite, and then topped it off with 5 to 6 inches of rainbow gravel, from Whittlesey.

To get the rainbow gravel, which ended up being almost a ton of gravel, I rented a pick-up from U-Haul again. My calculations suggested 1/2 a ton would be enough, but after one load, it was clear I was significantly off and only had, at best 2/3 of what I needed, so I made another trip and got another 1/2 ton. The actual numbers were 1140 pounds the first trip ($66.02) and 980 pounds the second ($42.43). The pick-up rental was $55.45 plus $13.05 in gas, and $1.50 to wash out the pick-up bed.

Once this was done, we just have to put the glass back on the frame. The assembly book from the manufacturer shows how the various size panes should be installed.

We had some breakage of panes in moving and cleaning, and had to buy 5 replacement panes ($48.66). The easiest place to do this was at The Hardware Store, since the big box stores -- Home Depot and Lowe's -- don't cut glass. But the Hardware Store only had single thickness glass, and it seems the glass being replaced is somewhat thicker (maybe double strength glass). Next time we should try an actual glass shop.

The panes are held in place by little clips and "glazing spring clips". Both of these are normally grey metal, and if you drop one (or it springs off), it can be hard to find. To make it easier, I spray painted them yellow.

But after a day of washing glass and putting it up, we have it all in place.

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