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Block and Backache

August 15, 2006

late-july-2006-055.jpgIn his comments to an earlier post “helping hands”, Jim mentions the new technology that I chose to build my house out of.  He is referring to insulated concrete forms – these are medium weight blocks, measuring 48″ long by 16″ high, by 10″ thick, and comprised of concrete and recycled Styrofoam.  The blocks have a 6″ hollow core, into which is placed steel rebar on 16″ vertical and horizontal centers.  Once poured, the walls provide R20+ insulation value plus the strength of a 6″ thick reinforced concrete “waffle” grid inside.  This building system is used in Europe and in the mid west.  This system is intended to replace structural framing for all but the interior walls, but I took the system a step farther and built full 2X4 framing plus engineered floor systems within, filling the wall cavities with wet cellulose insulation product for total wall insulation value of R33+

The nearest company and plant that produced the material I could find was in Texas, and I needed several tractor trailer loads of block to build the house.  Each block weighs between 75 and 100 pounds as the mix of foam and concrete varied.  This system is similar to standard ICF (Insulated Concrete Form) systems that are 100% pure Styrofoam in the way they are assembled and poured, but differ in that they are mixed with concrete integral to their casting. The benefit is that the they are stronger, stucco can be directly applied to them, and the poured concrete core chemically bonds with them.

I elected to install all 77,000 pounds of the form material myself, and to pour the 56+ yards of concrete in them as well. This took 4 months of weekends and evenings. The concrete adds an additional 224,000 lbs to the walls plus the steel.   I’ve poured over 136 cubic yards of concrete into this house, from footings to the roof.  Total weight is close to 700,000 lbs counting the framing and the steel tile roof.

The block was installed to a height of about 10′ by hand, standing on the ground, on scaffolds, and on a skid lifted by a loader.  After installing the first story, I called in a pump truck service and poured the first 36 yards of concrete.  I’m the one in the yellow raincoat.  The first driver took pity on me and gave me his raincoat telling me that I was in for a good splattering of cement.  He wasn’t kidding – That’s a 5″ hose line reduced down to 3″ and dropping from a height of 40′ feet.

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 The upper story was installed by hand, one block at a time using a rented basket lift, and the precast 4′ x 10′ panels were craned in place by myself, my fiance’ Leslie, and help from a few friends.  In these next two shots, we had just completed the assembly of 7 wooded forms, filled with steel rebar to cast the arches in place.  The second panel shows the completed results after the first floor pour, and framing continued upward with the concrete shell following along before the roof was completed.  The observant will note the use of convential 12″ concrete block in the columns supporting the arches.  I elected not to use the composite forms in this section as we would be supporting over 12,000 pounds of wet concrete being blasted into these plywood forms.  Once solidified, it is formitable in strength but while still liquid, concrete generates enough hydraulic force to explode the forms leading to one heck of a mess.

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