Building a First-Floor Slab and Walls with Concrete

The home's concrete-slab floor is constructed with foam decking and connected to PEX tubing that will heat the home. The ReddiForm foam blocks enable a single concrete pour for the first-floor slab and walls.

Clip Summary

Bob talks with Ron Ardres from ReddiForm about the construction of the home's concrete-slab floor. First, sidewalls were erected using ReddiForm expanded polystyrene foam forms. Then, ten-inch-deep foam decking is laid down, forming a ceiling over the basement story. The decking is temporarily supported with falsework until the concrete sets. Steel is placed using stirrups between the grooves in the foam blocks. PEX tubing, used in a radiant heat application, is put down on top of the foam, which is then covered with a rollout mesh. Bob talks with Jason McKinnon of Viega North America and with Tim Cutler, of TJ's Plumbing & Heating about the PEX tubing. Last, the concrete for the first floor slab and walls is poured, all at once, thanks to the ReddiForm blocks. The sidewalls are supported by a vertical bracing and scaffolding system, which prevent the walls from being blown out during the pour.
Okay, so Ron, we're standing on the actual concrete slab. Let's go through the steps. What happened first?

Okay, first we erected the side walls out of our foam block. Okay. Then, we span the entire floor with foam decking. It's ten inch deep decking with grooves in it.


And then we temporarily supported that with false work every six feet, to support it until the concrete sets.

But what about the steel?

Well, these grooves every two feet are for steel and you put steel in there with stirrups. Much like a parking garage. If you went into a parking garage you see these beams coming down.


And we're actually doing that, we're forming it right here, with foam.

Okay, and then the other element that's already included in there is the Pex tubing, right?

Yes. And that's put down on top of the foam after the steel is put in, after the steel rebar is put in. Then on top of that, on top of the Pex, there is a roll out mesh or mesh that goes down and then we pour it.

And of course the Pex tubing is what will provide the hot water for warming this whole environment.


And we learned all about Pex the other day.

What we got here is electronically cross linked polyethylene tubing. We got through a cross linking process which makes the tubing stronger, more resistant to high temperatures and higher pressures.

What we are going to do is take this Pex tubing and place it in the concrete slab.

Essentially, what we're going to do is create a low temperature radiator with the entire slab. We're going to have high temperature waters running through this coil.

As the water runs though the tubing, its going to dissipate heat into the slab, essentially creating that high temperature radiator. What that's gonna do is become the heat source for that entire area that we're trying to heat.

We're using the Pextron tubing.
In a radiant heat application, we evenly space the tubing across the floor. It heats the mass. We're not heating any air in this application.

We load the BTU's in to the mass. Our boiler looks at outdoor temperature and it modulates based on weather conditions.

So, we actually send exactly what we need to heat the building, though the floor. And it moves up and down based on design conditions, what's going on outside.

Our, our heat loss analysis here, showed nine inch spacing for five circuits. We used the electronically cross linked Pextron tubing made by Vega.

This, this tubing has 10,000 volts of electricity sent through it and the manufacturing process and it causes the molecules to cross link.
Once the molecule cross link, the tubing is virtually indestructible.

It also has an oxygen barrier sprayed on it, which protects the boiler and the heating system from getting any oxygen inside, which will cause a cast iron sectional boiler to deteriorate.

In our installation process for the tubing we use this plastic clip with prongs on it, and this foam staple gun right here, to just clip the tubing right to the foam.

And so once the pex is all in then you actually bring in the concrete.
You're pouring the slab we're standing on and that lower wall all at once?

Yes, exactly. and it's supported by vertical bracing, such as this?

I was gonna say, you don't have to worry about it, blowing out.


So , you've got this kind of bracing in place which is obviously incorporating ...

A scaffold.

A scaffolding system.


It's all in one, ok.

It's all in one.

And what's unique about this type of form is that you can pull it one cell solid lift.


10, 12 feet in the air, one shot.

Okay, so now we're ready for the next level of concrete.

And once this is poured, we'll start the second floor, and the gable side.