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
View Comments
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.