I was working solo, laying out sill plates for a Habitat for Humanity home with a slab-on-grade foundation. I had laid out the inside edge of the 2×4 sill plate by snapping a chalkline 31/2 in. from the edge of the slab. When it came time to mark the anchor-bolt locations in the sill, I hunted around for the Larry Haun-inspired bolt-hole marker that we typically use, but the marker was nowhere to be found. Fortunately, I found a way to make a marker from a scrap of 2×4 to do the same job.
As shown in the drawing, I clamped two 6-in. blocks of 2×4 together edge to edge. I used the bit for the anchor bolts to drill a hole at the center of the blocks where the edges came together. When I separated the blocks, each had a semicircular notch at the center of one edge. I drew a line from the center of the notch across the 3-1/2-in. face of the block and down the 1-1/2-in. edge, and carved a small notch for my pencil.
With the sill plate aligned with the chalkline, I placed the block over the sill plate with the notch bearing against each anchor bolt. Drawing a mark on the sill plate at the notch in the block gave me a bolt-hole centerpoint line exactly 3-1/2 in. from the centerline of the bolt. It worked like a charm.
—Kenneth C. Kelley, Ridgecrest, CA
Edited and Illustrated by Charles Miller
From Fine Homebuilding #202
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Ever think of using wedge anchors? (You know, where you lay the sill in place, drill through, blow out the dust and then drive in the wedge anchor.)
I can't imagine that a wedge anchor would ever pass inspection in California, where I'm pretty sure all anchor bolts must be in place prior to the pour for the inspector to see amidst a lot of #5 rebar. I don't live in CA though, and I'm not an engineer, and I don't pat myself on the back for chipping in on a Habitat home, so when in doubt, refer to the specifications.
Wedge bolts are not a good anchor bolt on walls. They work to resist pullout by expanding inside of the drilled hole. The use of a hammer drill introduces micro-cracks around the hole and the expansive force created by the wedge bolt can literally crack/spall the top of the wall.
Best anchors:
1 - Cast-in-place
2 - Epoxy anchored into hammer-drilled holes (or core-drilled holes if the wall of the hole is properly roughed).