Sill plates and foundation mistakes
Our first full day of doing our own work on the house involved installing sill plates:
These are pressure-treated 2x10s that rest on top of the foundation walls, with thin foam sill seals sandwiched between the concrete and the wood. The plates are 16 feet long, except where we had to cut them to fit, and are very heavy. They are bolted to the walls using threaded bolts that the foundation crew installed in the wall, and nuts and washers on top. We drilled 3/4 inch holes through the plates where the bolts would go. Because the bolts weren’t quite long enough for the nuts to be threaded on, we had to make 1.25 inch countersunk holes about a half inch deep on the top side of the plates, then used a socket wrench or crescent wrench to tighten the nuts.
The whole process was exhausting because the foundation was not backfilled, so we had to lift each plate eight feet to the wall tops from inside the foundation, while climbing ladders placed at each end of the plate. This had to be done twice. First, mark the locations of the bolts (by placing the plates level on top of the bolts and hitting them with hammers). Then lower the plates back down to the floor, drill the holes, place the sill seals on the wall tops, and finally raise the plates back up to the wall tops again and install the washers and nuts.
We also had to be very careful to make sure that the plates stuck out from the outside walls by 3.5 inches. We used chunks of 2x4 cut to the right thickness to do the checking. All of this care made for a long tedious process that took a day and half.
Our foundation plan showed very clearly the locations of the bolts, spaced every five or six feet in precise locations to avoid having beams rest on top of them. The foundation crew ignored these instructions and installed the bolts in random locations, so that we will have to notch any beams that fall on top of bolts. At least they installed the bolts at the proper 3 inches from the outside of the wall.
The foundation crew also ignored the instructions in the plans calling for steel mesh to be laid down before pouring the slab floor. Instead they used concrete with fibers mixed in. The result was cracks that appeared in the slab within a couple of days. Only one of the cracks was wide enough to stick a knife into, fortunately.
The moral here is to watch your foundation guys like hawks as they’re doing their work. We trusted our crew to follow the very clear instructions, and didn’t watch them all the time, and they made decisions that weren’t correct.