Anchor straps in lieu of bolts

Originally Posted By: jonofrey
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IRC 403.1.6 provides an exception to anchor bolts stated as follows:


"Foundation anchor straps, spaced as required to provide equivalent anchorage to 1/2-inch-diameter (12.7 mm) anchor bolts."

The IRC does not seem to elaborate any further.

The home I inspected yesterday had anchor straps spaced every five feet. My gut tells me this is not equivalent to anchor bolts.

It seems that builders are getting away from bolts and going to straps, must be cheaper.

Anyone know what the equivalent is?


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Inspection Nirvana!

We're NACHI. Get over it.

Originally Posted By: jremas
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They are not recommended for use with block walls. I only see them in concrete foundations and with the Superior Walls brand foundation.






Jeff Remas
REMAS Inspections, Inc.
Northeastern PA & the Poconos
www.NEPAinspector.com

570-362-1598

Originally Posted By: jfarsetta
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I see them everywhere, even with block walls. I think it has to do with cost (labor and skill) versus the traditional j-bolt.


Originally Posted By: roconnor
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I think your gut feeling about the strap anchors being inadequate may be right, because they typically must have a closer spacing to be equivalent to the anchor bolts.


The actual capacity of these strap anchors is established by the manufacturer, and the ICC has evaluation reports for most of them (like Simpson) as a substitution for the code required anchor bolts. The allowable capacity of a typical 1/2 anchor bolt depends on a lot of things (embedment, edge distance, wall strength, etc.) but is typically around 1,000# to 1,500# (IBC Table 1912.2), which is hard to match.

Most strap anchors just don?t have the same capacity (sometimes half the capacity unless they are the heavy duty ones), so you typically need more anchors at a reduced spacing. Manufacturers usually have tables for substituting strap anchors for anchor bolts, but some judgement is usually needed. Evaluating the required anchorage and what is equivalent to this is beyond a home inspection, and should be done by a building official or engineer.

If you are in an area with significant wind or seismic loading, and the strap anchors just don?t look right, it probably should be evaluated by an engineer.


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Robert O'Connor, PE
Eagle Engineering ?
Eagle Eye Inspections ?
NACHI Education Committee

I am absolutely amazed sometimes by how much thought goes into doing things wrong

Originally Posted By: roconnor
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Here is an example of some manufacturer’s strap anchor data, with substitution tables. They also make heavy duty ones, but I assumed you meant the typical light/standard duty ones.


http://www.strongtie.com/ftp/catalogs/c-hw02/c-hw02_page_17.pdf

Goes beyond a home inspection ... better to redirect to an engineer or AHJ if you think there is a real issue since there are a considerable amount of assumptions/restrictions in the beginning of the catalog. But I thought you would find that interesting as an example since you asked about acceptable substitutions for anchor bolts.


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Robert O'Connor, PE
Eagle Engineering ?
Eagle Eye Inspections ?
NACHI Education Committee

I am absolutely amazed sometimes by how much thought goes into doing things wrong

Originally Posted By: jonofrey
This post was automatically imported from our archived forum.



Robert,


That reference is a thing of beauty and answers my original question completely. Now I know for certain that a MAS strap anchor spaced 5' OC is an equivalent to a 1/2" anchor bolt spaced 6' OC.

Wow! Thanks.

I don't feel that verifying sole plate anchoring is going beyond a typical inspection as long as it's visible, however.


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Inspection Nirvana!

We're NACHI. Get over it.