Box on sill construction: fastening the floor to the foundation wall

Question

How exactly is the header fastened to the sill plate in box-on-sill construction using 2x dimensioned lumber?

Answer 1

The photo below shows detail of the rim board to the sill plate connection. Note that except for the high seismic activity areas, this connection does not need to be made very strong, as the rim board is essentially weighted down on the sill plate by the joists and flooring. The joists are connected to the rim board through head nailing from the rim board to the joists.

Answer 2

There should be anchor bolts embedded into the foundation wall.

• You drill holes through the sill plate that line up with the bolts
• Drop the sill plate over the bolts
• Place a washer and nut on each bolt
• Tighten the nuts down

Then, you hope that the guys placing the anchor bolts didn't manage to line any up with where a joist needs to go.

If there are no anchor bolts, you'd use some sort of concrete anchor like a sleeve anchor, drilling a hole through the sill and into the concrete, placing the anchor through them both, then tightening.

As noted by Lee Sam in the comments, once the joists are installed, the rim joist can be toe-nailed to the sill plate to hold it in place during construction, but it's the overlapping of the wall sheathing from the studs, across the joists and down to the sill plate, nailing according to the schedule in the blueprints (including nails through the sheathing into the sill plate) that holds the whole thing together into a solid, cohesive unit, which is then held to the foundation by the bolts described above.

Answer 3

You can use strapping to ensure that the walls are firmly attached like this:

Something like this is likely required in earthquake and hurricane prone areas. Probably a good idea almost anywhere else since high winds can occur nearly everywhere.

While this drawing shows the straps set in the concrete, I don't see that this is in any way a requirement. You could nail or screw the straps to the concrete after it's poured as well as nail or screw to the sill plate. I don't see any easy way to do it on the inside of the wall although you might get creative.

Answer 4

Barring extra measures taken for seismic zones, the wall sheathing makes the primary stabilizing connection there. As was pointed out elsewhere, the immense weight of the structure above the foundation virtually eliminates any chance of movement, but sheathing that's fastened to both the rim joist (not "header") and sill plate tie them together.