Rib Assembly Table
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There is no flat land where we live. Every thing is sloped. That helps with drainage but makes building things like these 50′ long greenhouse ribs a bit challenging. To ease the process of rib building Will constructed a 40’x16′ rib assembly table temporarily on the east greenhouse foundation. There he and Ben put together the five sections of 2.375″ pipe for each of the twenty-five ribs.
Siege Tower Rib Lift
They then lifted each rib up in succession to me where I reached down from our siege tower platform high above the worksite. That’s from where I took the photo of the assembly table as well – this explains the interesting perspective sweep of the top photo, my bird’s eye view.
I provide the muscle to lift the ribs up to the 21′ ridge line but I had no control over the ends of the ribs which needed to be set onto the feet attached to the greenhouse’s wooden foundation. The people on the ground socketed and bolted the feet to each rib and then I was able to set down the rib, also called rafters, with great relief. Each rafter weighs 225 lbs. The hard part was I wasn’t able to stand quite fully upright to hold the weight in order to make the pipes fit on the feet – I’m the variable spacer in this tower. By the end of the day my muscles, and the top of my head, were sore even with two hats.
First Six Ribs and North Header Beam
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To temporarily hold the ribs we put up vertical boards attached to the tractor’s siege tower. These held everything stable until we were ready to start attaching metal cross braces called purloins. Once we got got several ribs and purloins in place we built the north header beam which is attached to the first rib by metal brackets.
Attached to the header and one of the door pillars is a very long 2×8 braced with two diagonals that holds the first rib upright. Purloins attach the ribs together and diagonal pipes further stabilize it so the whole thing won’t accordion like a giant slinky. We’ll be adding a studded end wall that attaches the header beam to the rib all the way up 2′ on-center which will then get sheathing that provides shear resistance to prevent east-west movement, sideways in this photo since the greenhouse runs roughly north-south.
Tractor, Siege Tower, Greenhouse
(Click images for Big Picture)
The three doors below the north header beam create three bays in the greenhouse each of which is large enough for the tractor, a bulldozer or a big truck to drive through. The reason for the trucks is to deliver hay and wood chips. During the winter the deep bedding pack composts to generate both heat and food for the pigs and chickens.
The following year I can then grow pumpkins and the like in the rich soil which will be food for the animals the next cold season. The bulldozer and tractor are then able to push the composted material out the far end into the secondary compost pile south of the greenhouse as needed so that we can spread it on our orchards, fields and other gardens.
To get the siege tower in and out requires taking off the tower’s legs since it is considerably taller than a tractor trailer or dump truck. The height allows me to work on the ridge line, setting purloins, locking in screws and taping joints.
Will Cutting Lumber – Construction without Electrical Power
Although we were getting a steady wind of about 10 mph with gusts into the mid-20 mph range it was not too bad up on the siege tower because to the north west we have wind blocks consisting of Sugar Mountain, Bear Ridge, the two sets of line trees dividing our fields around the home field area and then the greenhouse south field plateau is dug down to get a level spot. All of this lifts much of the wind over us and should help keep the greenhouse warmer. The pigs prefer the south field in the winter for this reason which is why we migrate them to that side of the farm for the cold months. On the other hand, the warmer southernly winds come up the valley all summer and will flush clean air through the greenhouse during the warm months when I’m using it for plants.
The greenhouse will be 38′ wide by 96′ long with a center peak height of a bit over 21′. I call this a greenhouse which no doubt brings images to mind of a hot, humid, tropical closed in space filled with plants in the winter however that isn’t the way this one works. This has a greenhouse frame with a double greenhouse envelope cover for strength and infrared reflectivity back down but the south end of the greenhouse will be open and there are also openings for ventilation along the side walls and the top of the north end. Good ventilation is critical to good health. Humidity must be kept low. Dry is good. This is not a greenhouse for plants but a greenhouse for animals. The pigs and deep pack bedding compost heats the greenhouse along with solar gain. The goal is to make our chilly January and February months more like October or November and to make November-December and March more like September and April. The cover will also keep the snow off of the bedding which helps keep things drier.
One of the things that we have discovered over the past decade of experimentation is that the pigs like a bright sky overhead rather than the dark spaces. They will choose to sleep outdoors for this reason. Given two otherwise equal bedding spaces, they’ll pick the one with a glazed roof over the one with a dark opaque roof. What I think this has to do with is that sunlight lets ultraviolet in which kills off bacteria making for healthier animals. Each day is a sanitization cycle in a brightly lit space filled with natural sunlight. Thus the greenhouse.
Pig Winter Highway
The top priority residents of the greenhouse will be the farrowing sows who will get large open sections in the south end. From there they walk north along their trails to get their water and whey near the center of the farm. Piglets will wean to the well protected middle area of the greenhouse and then shift further north as shoats, growers, roasters and finishers who are able to follow their own trails up the winter paddocks to the whey and water during the cold months. By separating the sleeping areas from the water and whey we ensure the pigs get plenty of exercise and spread their manure and urine to fertilize the winter paddocks which become summer gardens.
Outdoors: 14°F/1°F Sunny
Tiny Cottage: 64°F/60°F
Daily Spark: If you are living a fictional life then the incidence of repeated first names is typically statistically low. The next question is does your name appear in the credits…