Scottpat Posted August 22, 2007 Report Share Posted August 22, 2007 I'm seeing this type of slab foundation more and more, but I do not know anything about this design. Any help would be great. This is being done by several builders, including a couple of national builders. The center pad is made by stacking bags full of crushed rock. Then the center is filled with crushed rock. A trench is then dug around the perimeter to form the footers. Foundation wall forms are then placed around the footers. Steel is then placed between the forms and the pad. Concrete is then poured into the forms. When it is done it looks like a raised slab foundation. Image Insert: 156.29 KB Image Insert: 136.07 KB Image Insert: 182.02 KB Image Insert: 151.95 KB Quote Link to comment Share on other sites More sharing options...
Jim Katen Posted August 22, 2007 Report Share Posted August 22, 2007 Originally posted by Scottpat . . . The center pad is made by stacking bags full of crushed rock. Then the center is filled with crushed rock. How do they compact the rock without knocking the bags out of place? A trench is then dug around the perimeter to form the footers. Foundation wall forms are then placed around the footers. Steel is then placed between the forms and the pad. Concrete is then poured into the forms. They're wasting a lot of concrete by using those bags as the inner form. They could use much less concrete by forming the walls traditionally and filling the interior with gravel several days after the forms are removed. Gravel is way cheaper than concrete and there's gotta be a significant cost associated with placing all those bags. The whole thing seems bassackwards to me. - Jim Katen, Oregon Quote Link to comment Share on other sites More sharing options...
Les Posted August 22, 2007 Report Share Posted August 22, 2007 never seen nothing like it. Quote Link to comment Share on other sites More sharing options...
Chad Fabry Posted August 22, 2007 Report Share Posted August 22, 2007 They could have a nice basement with less effort. Quote Link to comment Share on other sites More sharing options...
kurt Posted August 22, 2007 Report Share Posted August 22, 2007 Exactly. I'm still trying to figure out what's the benefit? Quote Link to comment Share on other sites More sharing options...
Scottpat Posted August 22, 2007 Author Report Share Posted August 22, 2007 What I have been told is that they build this type of slab when the area has a large amount of subsurface rock. It is cheaper than blasting out the foundations. Some builders use CMU blocks placed on a concrete footer. They still use the crushed rock for the pad but they don't pour the concrete walls. The CMU's will end up being about 4" higher than the crushed rock pad. Once the CMU's are in place, concrete is poured to the top of the CMU walls. My home is built that way. The two national builders that are using the bags of rock are Beazer and Drees. Quote Link to comment Share on other sites More sharing options...
Jim Katen Posted August 22, 2007 Report Share Posted August 22, 2007 Originally posted by Scottpat What I have been told is that they build this type of slab when the area has a large amount of subsurface rock. It is cheaper than blasting out the foundations. . . OK. Now I'm really confused. If that's the reasoning, why don't they simply cast the perimeter foundation and frame the first floor over a crawlspace. It would be a whole lot cheaper. - Jim Katen, Oregon Quote Link to comment Share on other sites More sharing options...
Kyle Kubs Posted August 22, 2007 Report Share Posted August 22, 2007 Originally posted by Jim Katen Originally posted by Scottpat What I have been told is that they build this type of slab when the area has a large amount of subsurface rock. It is cheaper than blasting out the foundations. . . OK. Now I'm really confused. If that's the reasoning, why don't they simply cast the perimeter foundation and frame the first floor over a crawlspace. It would be a whole lot cheaper. - Jim Katen, Oregon The first thing that comes to my mind is "very, very unskilled labor" needed for something like this = Cheap Cheap. Quote Link to comment Share on other sites More sharing options...
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