Saturday, February 19, 2011


The structural steel for the house should arrive the week of April 4, around six weeks from now. The steel pieces arrive pre-drilled so that they can be quickly bolted together on site. Part of the reason we're leaving the steel frame exposed is to show off the precision of the prefabrication system.

But before the steel can go up, a number of things have to happen in sequence:
the site needs to be excavated to make room for the concrete foundation, the wood formwork for the foundation needs to be put up, the underfloor utilities (drains, electrical conduits) need to be laid, and the concrete needs to be poured. The tricky part is coordinating the anchor bolts - these are large steel bolts that will attach the steel frame to the foundation. The anchor bolts need to be embedded in the concrete in the exact spots where the columns' base plates are drilled to meet them. Precise coordination between the subcontractors responsible for pouring the foundation, furnishing the steel and erecting the frame is essential.

Timing is important. The concrete mix we're using includes a substantial amount of fly ash, the waste left over after pulverized coal is burned in power plants. The fly ash has a lot of good qualities (it's a recycled material diverted from landfills, it produces denser concrete) but it also requires more time to cure (reach its design strength) than conventional concrete. We'll need to wait 28 days before we start loading the concrete with steel, which means we need to start pouring concrete by March 7 in order to have it ready for the steel frame to go up at the beginning of April. Which means excavation, formwork and subfloor utilities need to happen in the next two weeks.

It all has to happen in what Jonathan Richman would call Precise Modern Lovers Order.


  1. Best of luck with the timing! Up here, too much is dependent on the weather. When the concrete guys are out, shoot them while they layout the anchors. I'm interested in seeing how they ensure correct placement.

  2. Good idea, Adam. We'll document it. I'm really curious myself.

    It took me a while to realize you were talking about photography, btw.

  3. Curious...are you using a general contractor to select and ensure the coordination between the subcontractors? Is Ecosteel involved at all in contractor selection?

  4. We have a general contractor, and we'll blog a little more about the contracting process, soon. One drawback to using a steel frame system for a house is that contractors who build houses (like our contractor) have no experience with steel erection. We're relying on the steel erection subcontractor to coordinate the anchor bolt placement with the foundation subcontractor. Both we and the contractor are coordinating the process so that there are as many eyes as possible on the job. Ecosteel was able to locate one or two steel erectors for us to contact, though not the one we ultimately selected. This is Ecosteel's first job in South Florida, so they don't have many contacts down here.