mud sill strap/bolting and IRC

[Bruce A. King]

Did the IRC reduce the code requirements a few years ago where no strap or bolt is now required within one foot of a mud sill plate splice?

[James H. Bushart]

The IBC (2308.6) of 2006 requires a bolt or anchor strap not more than 12 and not less than 4 inches from the end of each piece.

[Jeffrey R. Pope]

Not that I am aware. . .

2003 IRC 403.1.6; 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.

[Marcel R. Cyr]

There is also an exception in the IRC that states foundation anchor straps, spaced as required to provide equivalent anchorage to 1/2"-diameter anchor bolts.

There are numerous types of hold-downs and each of them have there own installation requirements to be followed.

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.

On achor bolts, I believe if a two story, the spacing is upgraded to 4' o.c.
Correct me if I am wrong.

Hope this helps Bruce.

Marcel

[Barry Adair]

Originally Posted by mcyr

On achor bolts, I believe if a two story, the spacing is upgraded to 4' o.c.
Correct me if I am wrong.

Hope this helps Bruce.

Marcel

Section 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 D1 and D2, anchor bolts shall
also be spaced at 6 feet (1829 mm) on center and located within 12 inches (305 mm)
from 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 (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 R318 and R319.


Section 403.1.6.1 Foundation anchorage in Seismic Design Category D2.
In addition to the requirements of Section R403.1.6, the following requirements shall
apply to wood light-frame structures in Seismic Design Category D2 and wood
light-frame townhouses.
1. Plate washers conforming to Section R602.11.1 shall be used on each bolt.
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) from the ends of each
plate section when supported on a continuous foundation.
3
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) from 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.

[Richard A. Hetzel]

I believe anchor bolts on 4-foot centers is good practice, despite the code allowing 6-foot centers. Four feet was the standard before the IRC came into being. The IRC requirements for bolts on short pieces or near ends are a good addition to standard practice, though. I do not like straps at all, Period.