Greenhouse Wall Forms Wired

After getting up both the outer and inner forms for our concrete wall pour we needed to tie the forms together so they wouldn’t spread as the heavy liquid concrete splashed down into the forms. This took all day. It’s very important because there is a lot of force involved, far more than we would get with a 4′ high column of water because concrete is so much more dense.

The first step was to put long brace boards on the outsides of the forms. These run perpendicular to the form’s vertical brace boards. We then wired straight through the forms from one horizontal brace to the other. The steel wires are in tension – steel’s forté – making it so the forms won’t spread or bulge.

Long Drill

I drilled holes through the form – one above the long horizontal bracing and one below. The holes were also offset on either side of vertical braces as well. This produces an X of bracing that is supported by the wires to support the plywood of the forms and keep the liquid concrete in place until it cures.

Wiring the Forms

Feeding the wires through from one side is a little tricky. Get the wire very straight and then either peek over the top as you feed it, if possible, or look through the hole as you attempt to hit the center of the hole on the other side of the forms.

Wire Returning

This is best done by two people, one on each side of the forms. The person in back catches the wire and then sends it back through the other hole after properly placing it around the braces.

Usually I just twist the wires using the same technique I described for connecting rebar in the Iron Work post the other day. Unfortunately, occasionally a wire will break. Rather than rethreading one can set screws into the braces and tie off each end of the wire to those. Always good to have a backup plan.

Holly Fixing Gaps

We had a few spots where our footer was rough. In retrospect I would not have done the 4′ forms where I had to reach down into them to do the 2′ high footers. I was trying to avoid wasting wood but it produced an uneven footer top. Live and learn. In the photo above Holly’s filling the gap with additional 2×4’s and some foam in place. The wall pour will take care of the problem so the resulting structure will be 100% up to par.

Final Forms

The forms are all up, vertical and level. We added the diagonal braces and cinched a few pieces of rebar away from the form walls to the center of the concrete space. Everything is ready for the big wall pour.

Outdoors: 50°F/26°F Sunny
Farm House: 65°F/53°F
Tiny Cottage: 65°F/55°F

About Walter Jeffries

Tinker, Tailor...
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11 Responses to Greenhouse Wall Forms Wired

  1. Jenner Stevensen says:

    walter thank you for all the details of your posts i want to build a similarr kind of structur for our animals and youhave thought it all out i hope you will post plans maybe in pdf if you would that will give more resolution so i can see them clearly the layout from your blueprint yesterday was very helpful as is the final forms photo at the end good luck on your por

  2. Anonymous says:

    Do you like that drill? I am looking for a new battery operated drill. Mostly for screwing things together but also for drilling and all that stuff.

  3. Yes, I like that drill very much. We bought three in fact after using the first. It is a kit that comes with charger, two batteries and the drill. Here’s a Froogle for it.

  4. Would this greenhouse be the big project you alluded to earlier this year?

  5. Kathleen,

    Actually, the greenhouse was the project that got put on hold because of the “Big Project” that I alluded to earlier this year. The big project is still progressing but it is a very big project and we missed the schedule for where I wanted to be by September 1st in order to continue with construction on that for the fall. With that in mind I shifted gears and brought the greenhouse farrowing shed back to the front burner while paper work and research continues on the “Big Project”.



  6. Walter,
    As a builder (timber frames) I appreciate your detailed descriptions of the greenhouse project.

    Maybe you mentioned it in another post I haven’t read, but it is still unclear to me how your are framing the roof of the greenhouse.


  7. I haven’t gone into detail yet about the roofing, or about the level that is between the 4′ kneewalls and the timbers. Stay tuned! :)

  8. Jenner, I’ll post more details. The PDF is a good idea. I can generate that out of Illustrator which is what I use for my blueprints.

  9. Anonymous says:

    A most excellent family project. Simply amazing!

  10. edifice rex says:

    You did not want to use snap ties? I guess they are a little expensive.

  11. On occasion I’ve used ties. They’re really useful but don’t fit this job. :)

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