Mary in PA
We were so busy prepping for the slab that I didn’t start lining up concrete contractors until we were nearly done. I got together a list and made some calls. I thought that the contractors would come out, take a look, produce a quote, we would select one and be merrily on our way. But with each conversation I learned more about the process and the possible options, until the only thing that was clear was that we clearly didn’t know which contractor to select. All of the price quotes were in the same ballpark – so we’re basically talking about differences in how the concrete is produced and placed.
For placing the concrete, the fact that we had tied the rebar to their support chairs was an issue. Apparently common practice is to lay the rebar on the vapor barrier and then have the concrete crew pull it up into the wet concrete as it is being poured. This allows the use of a motorized wheelbarrow to get the wet concrete into the center of the building where the chute won’t reach. But it also raises a risk factor that during the rush of placing the concrete, the rebar won’t get pulled up into place, thus leaving the final slab much weaker. The solution to this problem is to use a pump truck or trailer to pump the wet concrete into the building, much like an ICF pour.
And a second issue was the type of concrete: ready mix from a concrete plant or metered (mixed on site). Honestly, I didn’t even know such a thing as metered existed until one of the contractors mentioned it. And I certainly didn’t know which was better for our application.
I decided to seek some experienced opinions at a forum called Construction Resource that I’ve used in the past. Many of the posts seem to be “from pros for pros”, but there are also some homeowner or owner-builder questions. I posted a few questions on the forum and got some interesting and useful feedback that helped us decide: Ready mix, pumped.
The only problem was none of the contractors were quoting that combination, nor seemed inclined to change their usual methods – which is fine. Personally I think it is much better to work hard to select a contractor who is already working in a manner that matches what you want, rather than ask a contractor to change the way they do things. Then I got smart (finally!). I called the ready-mix plant in our area and asked for two recommendations, and one of those – an Amish-owned business - was the one we hired. We set a date for the work in about two weeks' time, on a Friday, so John could be there too. Then we started reading up on how to best cure concrete (more on that to come.)
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