Greenhouse Wall Outer Forms


Holly bringing down a load of forms from the cottage level.

Our big fall construction project is a combination greenhouse and winter farrowing space. Like our previous temporary winter housing this will be an open shed which protects the pigs from the cold northern wind while allowing them plenty of fresh air.


Notice how the 20′ rebar sections are transported on 2×4’s.

The other week we stripped the footer forms. On those the knee walls are built pig tough out of poured concrete. The upper walls will be open block and glazing to let in the light. This is much like the south end shed which we built onto our old farm house for the pigs for winter farrowing.


Holly & Hope oiling forms so they peel easily.

For this year the roof will be simply plywood and plastic film. Another year as time and money allow we’ll do a glazed polycarbonate roof so that the space can double as a greenhouse to extend our growing season.


Holes need extra oil. 1 quart of oil covers 70 sq-ft.

The floor space of the greenhouse will double as a weaner space in the worst weather of winter by having the plant growing beds raised up off the ground. The pigs will help to heat the greenhouse with their generous donations of 103°F body heat.


First outer wall forms rising in the reference corner.

Pig heat combined with the earth wrapping around the greenhouse walls will help to temper the space during the depths of our northern Vermont winters without the need for auxilliary heating using wood or fossile fuels.

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Forms are locked to each other with screws.

We previously built a 70’x8′ greenhouse that tested some of these ideas and was heated by rabbits who also provided fertilizer for the plants.


Level footings make for rapid form placement.

The green house we’re building now is about four times larger. The roof will over hang significantly to shed snow away from the building and provide animal resting space in the shelter of the overhang. Water shed from the roof will be collected to animal waterers.


The orange capped rebar stubs sticking up by Ben will connect the footer to the walls.

The interior of the greenhouse will contain pillars at 12’x8′ spacing on a grid. This will allow us to easily change the configuration of the spaces on a moment’s notice. We can thus expand the greenhouse enclosed portion, expand farrowing spaces, winter bedding areas, poultry space, etc.


To the left in this photo is a bundle of 20 long #4 (1/2″ diameter) rebar for the walls.

The walls and pillars will all have vertical slots built into the concrete where boards can be dropped in to reconfigure the walls and spaces. Think of a grid of dots which can be dynamically interconnected to make different spaces of varying sizes as needed.


The outer wall forms grow, 4’x8′ sections at a time.

By making our form work as 4’x8′ sections we will be able to reuse it for other projects such as additional greenhouses of various sizes, tool sheds, the next section of our cottage, a tower, water tanks, etc.


Archimedes and Saturn up on the hill check out our progress.

Forms larger than 4’x8′ would be too hard to lift and carry. Forms smaller than that are less efficient use of materials and require more binding to make them strong and stable.


Sheep come by to investigate as more forms go up.

Even so, there are a few specialized form sizes such as the 1’x4′ and 2’x4′ forms that make up the serifs on the east corners of the C shape of the foundation and walls.


Neither rain nor snow nor driving wind stop our progress…

To make 12′ long sections of wall we also have a selection of 4’x4′ forms that when combined with the 4’x8′ forms give 4’x12′ sections. This is wide enough to allow the tractor to drive through to clean out the build up of winter bedding come spring. We leave the bedding in to build up over the winter because it provides a deep pack which composts generating heat that warms the animals through the colder months.


The wall forms are a little wavey in this photo without their diagonal and horizontal braces.


As we approach the concrete chute you can see it will need raising to fit above the wall.


Past the chute after raising it so it can deliver concrete from the truck to the tractor.

Like with the footer pour we filled with putty the heads of screws we would want to remove later as we disassemble the forms. This keeps the concrete out of the screw slots. Heads filled with stone means breaking the neck.


While we worked on forms John and Johnathan delivered our winter hay.

We left the top surface of the footers very rough so that when we pour the wall the concrete will have lots to grab onto. This helps make a better cold joint in addition to the stubs of rebar which will hold the two sections of concrete together.


Outer forms are finished!

A milestone! It felt good to get up the last of the outer forms. We need to do the steel work, that is to say rebar, and then we can install the inner forms.


Attaching Forms

We screwed the base of the outer wall forms to the footer forms. I should have left the inner footer forms on too to make this even easier on both sides.


Earth Layers

The photo above shows the different colors of the earth. The area where we sited the greenhouse I chose because we were able to dig unusually deeply into the hillside. On much of our land we hit ledge within the first foot of soil but here we dug down more than 8′ along the back edge and could have gone deeper.


Holly filling in some bigger cracks.

On the north section of footers we had deep forms that we had filled only up to a line rather than to the top. I had done that rather than making special forms. In retrospect it would have been worth making the special 2′ high forms for that footer as we did not get as even a footer there as I would have liked. We filled the gap with extra wood below the wall forms and then some foam in place. It works but would have been better to have done right the first time.

Outdoors: 56°F/39°F Sunny
Farm House: 57°F/47°F
Tiny Cottage: 55°F/50°F

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About Walter Jeffries

Tinker, Tailor…

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3 Responses to Greenhouse Wall Outer Forms

  1. EJ says:

    Wow you’ve been busy!
    I’m sure this will be a great improvement.

  2. farmwife says:

    Wow, looks like it is going to be great!

    Someone asked me the other day if we didn’t ever just get “finished” with all the projects. Nope!

  3. karl says:

    what a great experience for your kids to be part of. as always your project seems very well thought through. congratulations on the progress.

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