Will bracing the first inner wall forms.
In our quest for better winter farrowing we are building a combination greenhouse winter farrowing space. The greenhouse design is the cumulation and analysis of the last several years of experimentation we’ve done with a wide variety of temporary winter shelters for our livestock, in particular the pigs. This has ranged from pallet sheds to earthsheltered dens to wire ribbed greenhouses to haybale homes to pole sheds to the solar glazed south end shed. A common thread through all of them is that they are open to the outdoors so that the animals get plenty of fresh air. Even in our cold winters, the temperature is not the issue as much as having fresh air, dry bedding and protection from the wind.
Greenhouse Layout – 1 grid square = 1 foot
A couple of weeks ago we poured the greenhouse footers which then got stripped of their forms to reveal their strength and beauty. As the concrete cures to full strength we’ve been working on making the outer wall forms, raising the flume, installing the steel reinforcing and now the inner wall forms as we get ready to pour the kneewalls of the greenhouse. The greenhouse lower walls are made of steel reinforced concrete because pigs can be very hard on structures. Between their manure, back scratching and teeth they destroy wood in short order. Stone is my favorite solution but concrete is faster and even stronger as a whole. Additionally, the greenhouse is built into the hillside to give it a lower wind profile which will keep it warmer in the winter.
Note that the tractor can drive into the greenhouse to clean out bedding at the end of the year and deliver large round bales of hay. Over the course of the winter we let bedding hay build up to provide a deep bedding pack that helps to keep the pigs warm through the winter. The bedding begins to compost which generates considerable heat – warm toes! That compost is then a valuable resource for our gardens, orchards and fields.
Rail Groove Form Goal
The foundation of the greenhouse is 66’6″ long by 28’3″ wide and open on the south east side to catch the morning sun. Inside there will be 12 pillars to break up the roof spans into 8′ and 12′ long sections making the structure easier to build and stronger. These 8’x12′ also happen to be just the right size for winter farrowing nurseries. During the summer sows go off into the margins of the pasture to build a nest and get away from the herd when they farrow a new litter of piglets. About a week later they return with piglets in tow but for a while still keep to themselves. Unfortunately, in the winter these periods of isolation are much harder to achieve. Our solution to this has been to setup nurseries for the sows where they can be off by themselves or with one or two other sows that are farrowing at the same time in the winter. Up until now all these spaces have been of a rather temporary nature, changing from year to year using our various summer garden spaces. Getting the sows to those areas from their winter herd space can be tricky. The greenhouse with it’s easily reconfigurable sub-spaces will make that much easier.
Rail Groove Form Space in Inner Wall Forms
An essential component to this goal of easily reconfigurable spaces is that the interior of the greenhouse. Built into the wall and the 12 pillars we will have slots that can take rail dividers such that each of the 12’x8′ spaces can be sectioned off to create individual stalls. This way we can have a ring of stalls around the perimeter on the south, west and north sides with a central open area for the herd. Or perhaps we’ll find it works best with three lines of three farrowing nurseries and two open herd areas. The key is the interior is flexible and can be reconfigured in a day so that as our needs change the building can change to suite.
Rail Groove Form in Place
This same division also allows for areas to be set asside for greenhouse plant cultivation areas when we are ready to do that even in the winter. With a glazed roof, which we won’t be doing this year, a set of sub-sections can be easily turned into a green space and it can be heated by the pigs. Not only that, but by having the plants in raised beds the ground floor of the green space can be used as a piglet weaning area.
Rail Groove Mass Producting Jig
To make the rail grooves we needed form pieces that created thicker areas in the concrete walls and then a groove in the middle. In fact we needed a lot of these. When ever making many of something, I consider how I might speed up the process with a jig. The photo above shows the jig for making the Rail Groove Forms. I highlighted the pencil lines on the wood with magenta in Photoshop to make them more visible here. These marks show where to place the various parts and set the screws.
2×4 Parts Placed
Step one in using the jig is to place the long 2×4 that creates the groove in the concrete and the short 2×4 at the bottom that spaces the rail outward from the rest of the wall.
Rail Groove Form Screwed
The plywood is then placed on the 2×4’s using the reference marks on the jig and screwed into place. Most of the screws are 1-1/4″ screws but the one at the top of the form (bottom right of photo) is a longer 2.5″ screw as it will take more force when the forms are removed from the concrete.
Will Foiling the Forms
The photo above shows Rail Groove Forms in their pre- and post-foiled forms. Will is using a 2×4 jig to cut strips of Foil-Bubble-Bubble-Foil to tack onto the long vertical groove 2×4. If we just used a 2×4 to make the groove the resulting slot would be too thin to easily get rails in and out of. By wrapping the form in foil it thickens the form a little thus widening the resulting groove in the concrete walls and pillars by 1/2″.
Installed Rail Groove Form
This Rail Groove Form is in the south east corner of the foundation as it curles around in a serif to provide extra buttressing at that point. The extra thickening done every 8′ and 12′ around the perimeter wall also serves to strengthen the wall by adding buttresses.
Holly notching braces and rail groove 2×4’s for header long brace.
Notched Braces and Rail Groove Boards
The cross braces that join the two walls will be removed as we fill the final bit of concrete into the forms in order to get a smooth top to the wall.
Header Brace in Place
The purpose of the header brace is three fold: 1) it locks all of the form pieces together; 2) it straightens the wall; 3) it widens the wall for the top 1.5″ inches creating an I-beam and thus a much stronger wall while using less concrete than if we had made the entire wall that thickeness.
Walter Holding Spacer Block While Will Screws Header Braces Down.
Again, a simple little jig makes the process go faster. No need to use a measuring tape over and over.
We signed and dated the greenhouse by writing on one of the inner wall forms using silicon sealant. The bead of silicon hardened and now when the concrete goes into the form it will act as a mold. When we peel the form we’ll have the year and our name imprinted in the wall.
Outdoors: 50°F/26°F Cloudy, Miniscule rain in morning
Farm House: 65°F/53°F 2 round bales out N & S
Tiny Cottage: 65°F/55°F