Barn Project, Part IV pouring the slab

With the frost wall back filled and the center of the foundation filled it, it was time to get ready to pour concrete.  The first thing that went down was a vapor barrier, consisting of 20 mil poly plastic.

Then 4 inches of polyisocyanurate insulation with a foil backing.  The hollowed out sections of concrete block were filled with vermiculite.

Ready to pour concrete

Ready to pour concrete

A layer of 4 inch steel mesh wire was laid on top of the insulation, held up with medium sized rocks.  Attached to the mesh was 1/2 inch pex for in slab radiant heating.  Finally, the outside of the block wall was formed and 1 inch of foam insulation was run around the outside.

Pouring concrete for slab

Pouring concrete for slab

Finally, it was time to pour concrete.  In an almost surreal moment, the temperature moderated and on Friday, January 13th we were able to pour the slab in 56 degree weather.  Overnight, the temperature went down to 34 degrees then back up to 56 the next day.  If this is climate change, I am not complaining.

Barn Project slab poured

Barn Project slab poured

The total slab was about 8 cubic yards, 240 inches x 192 inches x 8 inches = 368, 640 cubic inches or 7.9 cubic yards, which cost $709.00 delivered, mixed and poured by the ready mix truck.  Thankfully, the previous night had been cold and the ground was frozen solid.  The entire pour took about 45 minutes.  Since the weather was warm and forecast to stay above freezing, I did not get accelerant added to the mix.  By 4 pm, it was hard enough to smooth finish.

I kept a tarp over it for three days.

The total cost for the insulation, reenforcing wire, pex, concrete and labor was $2415.39

The running total $5,156.62

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3 comments to Barn Project, Part IV pouring the slab

  • Fun project Paul! I’m surprised to see the foil faced polyiso down. Typically we use regular XPS. Are you worried about the foil facing deteriorating with a reaction to the concrete? Just curious as it seems like a good idea but I haven’t seen anyone do it that way before.

  • Paul

    Todd, now I will have to experiment with the left over foil faced insulation and concrete to see what reactions there are. I saw an slab poured like this a few years ago, the architect said the foil acts as a radiant barrier. If it does deteriorate, I suppose there is nothing I can do about it now.

  • I figure it can’t really hurt in that use. Most of the time we avoid foil faced polyiso against interior finished space because the aluminum reacts with the concrete.

    Cool project!!

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