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By Kenneth in Lees Summit, MO on 12/14/2005
I know Dean Reinke quite well, saw him a couple of weeks back when he helped me finish hooking up and tuning in my surround sound system. He was my ICF subcontractor, but this relationship has carried on beyond that phase of my house - great guy.
The house you are looking at was his personal house, also a demonstration house for his business - I have been there and will try to answer some questions. That said, you may wonder why an ICF builder built part of his house using sticks? The answer is that the stick framed portion of his house also used spray foam insulation, and is top quality stick-framed construction. The idea here was a contrast of two building techniques (ICF vs. good traditional). From inside, you cannot tell where one technique (ICF) stops and the other (stick) starts. However when you walk down the hallway, you "feel" a distinct difference. The ICF is quieter and just generally feels different, it is difficult to explain. Even people who have been in ICF houses don't realize how different they are, but Dean's demonstration house serves this purpose.
Another innovation in his house is that the top floor doesn't match the same floorplan of the main level (look at the bumped out area in the fourth row down). While conventional ICF wisdom would say this is not possible, engineering would say that it is possible, and Dean would say that construction is feasible as well.
Now then, the "Reverse Slab on Grade" is a term coined by Dean, and is really closer to crawlspace type construction, but with no crawlspace. Around here, slab on grade would have footers trenched at the edges of the slab (and any places for columns or support walls) and the entire slab and footer would be poured as one monolithic piece. Dean's theory is that the concrete is in direct contact with ground (specifically the ground outside the footprint of the house), concrete is a poor insulator, therefore your slab and floors will always be cold. If you notice what Dean did was he excavated ~36" deep to pour his footers, very similar to what slab-on-grade would do, but he poured normal sized footers (well larger than normal, 24" wide x 12" thick). He then builds the ICF up on these footers to just above the level of the slab and fills these blocks. Next he pours the slab, and uses this to set the truss template so that floor and roof trusses can be ordered based on actual measurements (critical for truss construction, don't order these based on drawings) while the walls are being constructed. Dean's theory is that the concrete slab (floor) is now thermally separate from the ground outside the footprint of the house itself (insulated by foam, a good insulator). While the slab is still in direct contact with the ground directly below the slab, Dean's theory is that this area will fairly quickly equalize to roughly the same temperature as the house, kind of a bubble in temperature directly under the house footprint.
I have seen no calculations to support this conclusion. At the same time, it makes some sense. I used this technique, but mainly because Dean was my ICF subcontractor, poured my footings, and ultimately this is how he liked to work. In my original drawings, I was going to use a monolithic slab with the edges trenched to the necessary depth, and the area under the floor insulated with a dense foam insulation. Dean's technique used less concrete (figure a 2' wide trench 36" deep, lots of concrete here), saved me the under slab foam insulation, and in practicality works as he said it would as my basement floors are not cold as my other house that used a more traditional construction.
I tried to explain it as I understand it. If you have any questions, pm me and I can put you in touch with the source. Alternatively email Dean, he is always happy to answer questions about ICF, whether or not you are in an area where he would be interested in building your house. He is truly committed to ICF, the benefits, and is willing to share this commitment to anyone that will give him an opportunity.