I'm building a workshop in my backyard with 2x4 walls. I put 5/8th J bolts in the slab when I poured it but ended up with break in the bottom plate too far from the anchor bolts so the inspector told me I needed to add a couple. Which is fine but I'm having a hard time figuring out the size anchor bolts I need. Everything I'm reading says that the wedge bolts need 5 diameters from the edge of the concrete. Which on a hole centered on a 2x4 wall would be 1/4" max. There are alot of big beefy J bolts in the slab so I'm not worried about functionality but I have a feeling an inspector isn't going to sign off on 1/4 inch anchor bolts. Is 1/4 inch up to code? Or can I get away with a bigger bolt? Or is there another kind of anchor I don't know about?
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2Why not just ask the inspector?– JACKCommented Feb 27, 2022 at 14:44
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Time mostly. Won't be able to get ahold of him till next week and was trying to get this knocked out while I have the weekend off.– FrozenTexanCommented Feb 27, 2022 at 16:49
2 Answers
Code requires a 1/2” minimum and extend 7” into masonry or concrete and a maximum of 6’ on center. Plus one shall be 12” within end of wall and a minimum of 2 per plate. (See R403.1.8)
In seismic zones and high wind areas all that changes.
The Code requires an edge distance based on the size of the bolt:
- 1/4” = 1 1/2”
- 1/2” = 2 1/2”
- 5/8” = 3”
This is based on standard grade concrete, (i.e.: 2500, 3000, etc.) If you use a “high-strength” concrete it can be reduced. (See ICC Chapter 19, Table 1908.2) Generally, I see “J-bolts” installed after the foundation wall is poured. This is primarily because we want a smooth surface for the sole plate to rest on. The bolts can be wiggled into the concrete and twisted so it hooks under the top horizontal rebar, which should be approximately 3” clear down from the top of the wall. Yes, 10” anchor bolts are now required with 3” square washers in any high-wind or seismic area.
You might be able to find a chemical anchoring system that meets your requirements as they typically have a shorter minimum edge distance. These come in many variants such as epoxy, acrylic, hybrid polymer, etc. and there are many manufactures.
You'll need to find what's available near you and refer to the that manufacture's instructions.
