In the typical construction project, I suppose you need to start with the ground and move upward. I took the opposite approach and started form the roof, and moved through the skylights, doors and windows, walls, flooring, foundation, and earth. I’ve already selected the windows, skylights, roofing product, and building system, but have not selected the foundation yet.
I thought it would be easy. you have two choices in general in seismic design category D, continuous foundation walls, or concrete masonry units (CMU). I’ve investigated all sorts of technologies in anchoring a structure to earth. Everything from metal helical rods, posts and grade beams, and every type of gluing scheme. The foundation not only holds up a home, but acts the interface between the earth (air, water, fire) and your dry structure. It has to prevent moisture buildup underneath, hold fast during movement, and last longer than what stands on top of it.
I got the definitive word form APEX block that their lightweight composite ICF solution is not approved nor likely to be approved in the city of Los Angeles for many months. I have to select a plan B, which is either a tradition six inch formed footing and stem wall, or an alternative forming system, like an ICF. My idea is to eliminate concrete, or at least reduce it. The APEX system took this structure down from 6.63 cubic yards (cu yd) of cement to just 4.70 cu yds. All other systems reduce concrete use, but the next best system I could find was a waffle grid ICF called American Polysteel PS 3600, which will use 5.70 yards of concrete. Why this matters is concrete should be used where needed, and not extravagantly, because it has a extremely large carbon footprint in its manufacture. Concrete is also very, very heavy, and takes a lot of diesel to transport. That’s why CMU’s are out of the question.
The Polysteel forms weigh in at 7 pounds, compared to a CMU at 60 pounds. I calculate I’ll need around 75 blocks, saving over 2000 pounds from a flatbed truck. I’m hoping to design a monolithic pour of the footings and stem walls using some materials I found on the internet from Award Metals. they make a novel footing brace and monolithic strap that should accommodate the ICF forms. I chose the waffle grid, which by simple by having a irregular mold shape, it uses much less concrete than a form that has straight walls. I’m also hoping that since the walls will only be 22 inches high, my building and safety department will not require a stamp of a structural engineer.
I do have a few engineer names that specialize in ICF foundations, just in case. It’s always down to the budget. My time is basically free. This project has cost very little so far, but with professional consultants, I’m sure the fees go from zero to $1,500 really fast. I found the names through the newsletter of the Structural Engineers Association of Southern California. I hope I don’t need to call them.