Code question

[Eric]

Codeman,

I am attaching a sill plate to a concrete slab. I am going to use sleeve type or wedge anchors. What length do they have to be? They will be in 2x4 and 2x6 plates. I've looked in the building codes and can't seem to find the info. Thanks for the help!

[Jerry Peck - Codeman]

Hi Eric,

Being as you did not put your state or location, I will respond with the 2006 IRC, presuming this is a residential dwelling unit.

Also, there are many variables I do not know, thus I will provide the basic prescriptive requirements from the code.

From the 2006 IRC. (underlining and bold are mine)
- R403.1.6 Foundation anchorage. When braced wall panels are supported directly on continuous foundations, the wall wood sill plate or cold-formed steel bottom track shall be anchored to the foundation in accordance with this section.
- - The wood sole plate at exterior walls on monolithic slabs and wood sill plate shall be anchored to the foundation with anchor bolts spaced a maximum of 6 feet (1829 mm) on center. There shall be a minimum of two bolts per plate section with one bolt located not more than 12 inches (305 mm) or less than seven bolt diameters from each end of the plate section. In Seismic Design Categories D0, D1 and D2, anchor bolts shall be spaced at 6 feet (1829 mm) on center and located within 12 inches (305 mm) of the ends of each plate section at interior braced wall lines when required by Section R602.10.9 to be supported on a continuous foundation. Bolts shall be at least 1/2 inch (13 mm) in diameter and shall extend a minimum of 7 inches (178 mm) into masonry or concrete. Interior bearing wall sole plates on monolithic slab foundation shall be positively anchored with approved fasteners. A nut and washer shall be tightened on each bolt of the plate. Sills and sole plates shall be protected against decay and termites where required by Sections R319 and R320. Cold-formed steel framing systems shall be fastened to the wood sill plates or anchored directly to the foundation as required in Section R505.3.1 or R603.1.1.
- - - Exceptions:
- - - - 1. Foundation anchorage, spaced as required to provide equivalent anchorage to 1/2-inch-diameter (13 mm) anchor bolts.
- - - - 2. Walls 24 inches (610 mm) total length or shorter connecting offset braced wall panels shall be anchored to the foundation with a minimum of one anchor bolt located in the center third of the plate section and shall be attached to adjacent braced wall panels per Figure R602.10.5 at corners.
- - - - 3. Walls 12 inches (305 mm) total length or shorter connecting offset braced wall panels shall be permitted to be connected to the foundation without anchor bolts. The wall shall be attached to adjacent braced wall panels per Figure R602.10.5 at corners.
- - R403.1.6.1 Foundation anchorage in Seismic Design Categories C, D0, D1 and D2. In addition to the requirements of Section R403.1.6, the following requirements shall apply to wood light-frame structures in Seismic Design Categories D0, D1 and D2 and wood light-frame townhouses in Seismic Design Category C.
- - - 1. Plate washers conforming to Section R602.11.1 shall be provided for all anchor bolts over the full length of required braced wall lines. Properly sized cut washers shall be permitted for anchor bolts in wall lines not containing braced wall panels.
- - - 2. Interior braced wall plates shall have anchor bolts spaced at not more than 6 feet (1829 mm) on center and located within 12 inches (305 mm) of the ends of each plate section when supported on a continuous foundation.
- - - 3. Interior bearing wall sole plates shall have anchor bolts spaced at not more than 6 feet (1829 mm) on center and located within 12 inches (305 mm) of the ends of each plate section when supported on a continuous foundation.
- - - 4. The maximum anchor bolt spacing shall be 4 feet (1219 mm)for buildings over two stories in height.
- - - 5. Stepped cripple walls shall conform to Section R602.11.3.
- - - 6. Where continuous wood foundations in accordance with Section R404.2 are used, the force transfer shall have a capacity equal to or greater than the connections required by Section R602.11.1 or the braced wall panel shall be connected to the wood foundations in accordance with the braced wall panel-to-floor fastening requirements of Table R602.3(1).

This section is typically referring to embedded anchor bolts, embedded into the concrete or grouted masonry the depth specified (which is specified to be 7 inches minimum). The underlined Exception 1 allows for other alternatives which shall "provide equivalent anchorage". The sleeve or wedge type anchors would need to be looked up on the manufacturer's charts to find their comparable uplift resistance and the associated depth which provides that. You should be able to obtain that information from where you purchased the anchors, or from the manufacturer's web site using the style/type anchor you are considering.

As an example, if the sleeve/wedge anchors you are proposing to use are equivalent to embedded anchors at an equivalent depth, then you would need 7 inch minimum embedment plus 1-1/2 inches for the thickness of the sill plate, plus the thickness of the washer (maybe 1/8 inch), the nut (maybe 5/8 inch), and additional thread (figure 1/2 inch) which means the anchor will need to be 7 + 1-1/2 + 1/8 + 5/8 + 1/2 = 9-3/4 inch long sleeve/wedge anchor minimum.

That part of the code is prescriptive in nature, doing it a different way or using material substitutions may well result in a structure which does not meet code unless engineering is provided which states that it does meet the requirements of the code. In this case, the manufacturer's information may be acceptable to your local AHJ (Authority Having Jurisdiction) as a substitute for any additional engineering.

Hopefully this information will help you arrive at your final depth requirement.

Codeman

[Eric]

So sorry, I am in Pierson Florida and this is a residence I am building. Thanks so much for your help!

[Jerry Peck - Codeman]

Hi Eric,

The Florida Residential code says the same basic thing, if not the exact thing.

This is from the 2004 Florida Building Code, Residential, w/2006 Revisions. (underlining and bold are mine)
- R403.1.6 Foundation anchorage.
- - When braced wall panels are supported directly on continuous foundations, the wall wood sill plate or cold-formed steel bottom track shall be anchored to the foundation in accordance with this section.
- - The wood sole plate at exterior walls on monolithic slabs and wood sill plate shall be anchored to the foundation with anchor bolts spaced a maximum of 6 feet (1829 mm) on center. There shall be a minimum of two bolts per plate section with one bolt located not more than 12 inches (305 mm) or less than seven bolt diameters from each end of the plate section. Bolts shall be at least ½ inch (12.7 mm) in diameter and shall extend a minimum of 7 inches (178 mm) into masonry or concrete. Interior bearing wall sole plates on monolithic slab foundations shall be positively anchored with approved fasteners. A nut and washer shall be tightened on each bolt to the plate. Sills and sole plates shall be protected against decay and termites where required by Sections R319 and R320. Cold-formed steel framing systems shall be fastened to the wood sill plates or anchored directly to the foundation as required in Section R505.3.1 or R603.1.1.
- - - Exception: Foundation anchor straps, spaced as required to provide equivalent anchorage to ½-inch-diameter (12.7 mm) anchor bolts.

Codeman