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I have an existing 48"x48"x4" thick concrete pad sitting atop gravel/crushed stone that goes down to the frost depth. The pad was poured with the idea being that a water tank would sit on it, and then walls would be anchored down around the sides along with insulation. The pad is comfortably sized to allow for the water tank plus the walls/door, but with not a lot of extra space.

I'm now trying to figure out the anchorage for the walls. I've run into an issue sizing anchoring connectors that will comply with IRC. R403.1.6 in my case requires 2x 1/2" anchor bolts embedded at least 7" into concrete. For obvious reasons, I cannot put a 7" anchor bolt into a 4" concrete slab -- the bolt would stick out below. Also, the slab is already poured.

R403.1.6 exception 1 allows for any other anchorage that is equivalent to the bolts. I have been looking at a variety of alternate connectors. (TapCons, etc.) However, all of them have a decent critical distance from the edge of the concrete before they are allowed to be used at full load. Since I need my walls to sit on the edge of the concrete, that isn't practical.

To make matters worse, one side of the shed is composed almost entirely of a door, leaving only a limited amount of sill plate on either side of the door for anchorage.

Can anyone recommend an anchoring strategy that will comply with code?

  • I appreciate your interest in following code to the letter, but in all my years of building I don't think I ever saw a mason use bolts that would reach 7" into the concrete, and never once was it an issue for an inspector. Common sense and experience tell me that your wall will tear apart in a storm before a 3" wedge bolt will pull out. – isherwood Feb 9 '17 at 16:37
  • @isherwood I wish, but the inspector where I live is extremely strict and requires 100% compliance. – David Pfeffer Feb 10 '17 at 0:58
  • Just out of curiousity, how would your inspector know it went down 7" or not? Is he digging your foundation out to see its depth? Is he putting the anchors in? 7" is a pretty thick slab. My patio is maybe 4" with post supports holding a full roof on top. My shed slab is maybe 4". I don't even think my garage wall footings are 7" thick. Even if I had a 7" bolt, the bottom of the bolt would stick out. – Jeff Cates Feb 12 '17 at 3:28
  • @JeffCates He will likely investigate the slab thickness with a metal rod, since this didn't require a footing/foundation inspection. – David Pfeffer Feb 12 '17 at 13:29

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