It’s all about the connectors

So far I’ve come up with a number of ways to connect together the layers of my wall. As I mentioned before, Owens Corning has a push through connector that comes in various lengths. This product is sold in conjunction with their PinkCore XPS foam. Composite Technologies has a system of connectors which require predrilled holes which is designed to be used with Dow rigid insulation. Composite Tech hasn’t answered my queries regarding their product. I’m suspecting they only deal with builders, as does Owens Corning. I would have to get the product from one of their distributors.

But, I’ve come up with a really nifty third connector, a low tech, low cost approach that will work for me. Drum roll please! Threaded nylon rod. I’ve found at least two companies that offer this product. One obviously manufactures the product because they can offer it in any length for all the thicknesses they produce. The other has various thicknesses in 12″ lengths, so it’s a product they order from a manufacturer, not a product they produce themselves.

I’m viewing threaded acetal rod as a good connector for my app because my connectors don’t have to be very structural, they just have to hold everything together while the wall is being moved into place.

For my app (tiltwall of 6″ papercrete, 1″ foam, 1″ ferrocement) it will work. It can be cut to length or ordered in a certain length. If I need a stop I can thread one on. If I need more holding power (around windows, doors and edges) I can spin on a nut. And it should have enough flexibility to allow the layers to expand or contract without causing cracking of the ferrocement layer.

My concern is not how the connectors will hold in the ferrocement wythe. How will they hold in the papercrete layer? Will the papercrete back away from the nylon as it dries? How far into the papercrete do I need to sink the connectors to get really good grip? I have a six inch layer to work with, but don’t want to waste material or have the rods interfer with placement of boxes and conduit.

The papercrete layer cannot be constructed at the same time as the ferrocement layer because the papercrete must be able to breath on all six sides until it’s dry to maintain uniformity. The foam layer cannot be laid immediately on the papercrete layer because it will prevent drying. If I were doing cement/foam/cement (or ferrocement as the case may be), I could lay my first wythe, lay on the foam, apply the connectors, lay my last wythe and walk away until it’s set. Using papercrete, I can’t do that. The papercrete layer has to dry, then the foam and connectors are applied, then the ferrocement wythe is laid. I have to have a method by which I can get the connectors, foam and papercrete married without a lot of extra work or hassle.

There’s a couple different ways I can approach putting the connectors in place.

If I have a jig I can lay on the papercrete layer to produce the holes in the papercrete, once the papercrete layer is dry I can glue the nylon rod in with white glue. With this method I have to figure out how to thread the rod through the foam. Drill holes? Trying to lay foam on a bed of protruding nylon rods could really be a bugger. Lay the foam first? Trying to drill the foam to match the holes in the papercrete could also be a bugger. I don’t think I want to try and drill holes into the papercrete, though I’m sure that could be done. Not easily, as my papercrete will have sand in the mix. As you can see, I’m still pondering this step.

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