Its been a couple of days since I poured my slab and I thought it would be good to share some observations that might save others trouble with their own builds.
Concrete trucks are really heavy
No I mean really heavy. The driveway that I drive on all the time with my small pickup truck is hard packed and my truck tires leave little if any impressions. The concrete truck left 3 inch deep ruts in a couple of places! Additionally, when the truck delivers material the driver needs to drive forward and back to deliver it to the correct spot. Make sure your ground is solid. The driver makes you sign a paper saying you are responsible if he gets stuck.
Rakes and Hoe’s Suck
Moving concrete around in the forms can be done with a normal garden rake but a concrete rake is much better. Unfortunately, it’s a specialized one use tool but worth the extra money IMO.
Some people may also consider a bull float a necessity. If you are looking for a shiny smooth slab then it probably is. In my application where there will be a sub-floor over the cement, I think the skreet I used would have provided a suitable (but rougher) finish. Since my brother in-law had access to a bull float I used it but it was not needed.
Bagels make lousy feed for your helpers
I bought a bunch of nice bagels and OJ and no one ate them. My brother in-law arrived an hour late with a dozen donuts and everyone devoured them. Lesson: Donuts not bagels!
Attaching foam to your slab
You will want to attach the foam boards to the slab with some type of mechanical fastener. Had I used 2 inch thick foam there are commonly available concrete fasteners at the local home store. I am using 4 inches of foam and there’s nothing available so I had to improvise.
Building codes now require AQT compatible fasteners for deck construction. Timberlok makes all sorts of fasteners to fill that need. There are also a number of generic options at the local home store. I found some green 5 inch epoxy coated lag screws with a star drive head. These fasteners are not rated for use in concrete, however in this application they do not need to hold very much load. You just need to hold the foam against the concrete. I paired these fasteners with some galvanized roof tin washers to do this job.
You need a 6 inch long 5/32 masonry bit and a hammer drill to make this work. First you drill a hole thru the foam boards into the concrete. Using an impact driver, you drive the fastener into the drilled hole being careful not to drive too deep and strip out the hole you drilled. You may find that applying a 5 minute epoxy to the threads will produce a stronger bond to the concrete (I did not use it however). I did this on a 3 day old slab which may have helped just a bit with the concrete being softer. I would also say that an impact driver is needed to complete this job. With a depleted battery I was not able to drive the fastener in all the way, but a fresh battery worked fine.