Patrick's Barn: Underslab Insulationcomments (0) June 3rd, 2011 in Blogs
How not to estimate a construction project
A few years ago, I gave up telling people how long my building and remodeling projects would take to complete. It was just too demoralizing to think that even my most generous estimates would prove to be wildly unrealistic. This past weekend shows just how wrong I can be.
My plan for the three-day weekend was to level the gravel pad, install the sub-slab insulation, place and tie the rebar, and finally finish up the formwork. I even thought I might do all this work in a single day, maybe a day and a half. Unfortunately, I didn't even get close to finishing, even while working 20+ hours over the three days.
My wife and I did make good progress, however. We started the weekend by leveling the gravel using a jig inspired by a Fine Woodworking article that showed how to make a Nakashima-style slab table. The woodworker used a big sled-mounted router to level the table top. I adapted the technique to level the machine-placed gravel so the slab would have a uniform four-inch thickness. Thanks to my wife, who helped me throughout this process, it only took a half day, but that was still twice as long as I had originally thought. The rest of the day was spent getting material for the following day's work.
Sunday was spent placing the insulation and then cutting and fitting the foam around the 17 piers that make up the building's foundation. Once again, I greatly underestimated how long this would take. I figured on a couple of hours, but it ended up taking almost all day. The next day I worked on placing and tying the rebar as best I could, but I was really beat from the day before and the weekend's unusually hot and humid weather. When it came time in the early afternoon to go to a friend's Memorial Day picnic, I was happy to throw in the towel.
You can read more about my barn here.
It should be easy to finish up the rebar and formwork this weekend, though. My plan is to pour the slab on Tuesday—I hope the weather is good the next few days.
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