To keep houses from shaking apart in earthquakes or being
blown away in hurricanes, engineers and architects specify
hold-downs, metal framing connectors, and plywood shear
paneling. The idea is to use metal connectors and plywood to
create a continuous "hold-down path" that ties the structural
wooden frame together from foundation to roof peak. In
California, where I live and work, every set of house plans
addresses the issue of tying the structure to the
Scan the Plan
of hold-down hardware, whether it’s a simple 1/2-inch
J-bolt or a custom metal clip, will be marked on the foundation
plan and in the structural details. When reviewing a set of
plans, I use a colored marker to highlight every hold-down and
shear panel anchor bolt. As I mark each one, I keep a running
count of each type and familiarize myself with their locations.
Hold-downs are typically called for in pairs, located, for
instance, at each end of a shear wall or on both sides of a
window or door where the shear wall is interrupted by the
opening (see Figure 1).
Scanning the PlansFigure
1. Hold-down installation begins with a careful review
of the plans. An overlooked hold-down bolt or embedded strap
can turn into a costly retrofit once the slab is poured. The
author uses colored highlighters to locate every piece of
hardware specified by the engineer.
With experience, it’s pretty easy to find (and even
memorize) the location of the hold-downs.
Although we usually keep an extra supply of the most popular
clips in the storage shed, it’s expensive to go back and
do a special installation of an omitted hold-down, especially
for the larger, more costly anchors. So if you are new to these
kinds of anchor systems, be prepared to do a close examination
of the plans to avoid a costly retrofit installation.
Nevertheless, this is a common problem, especially on a
complicated set of plans. If you do omit a hold-down, ask your
structural engineer for a solution. For example, a common fix
for a missing foundation anchor is to drill into the foundation
or footing and install a retrofit bolt or a length of threaded
rod, secured with epoxy.
The plans I get from architects are very specific, and
it’s my job to locate the foundation hardware and to see
how it will connect to the shear walls, and to the door and
window openings. I look for places where some other building
component, such as waterlines or power conduits, might
interfere with the installation of the hardware. If the house
has a second story, I’m careful to note any connection
called out between floors so that my framer can adjust the stud
and post layout to accommodate the connecting hardware.
I then turn to the roof framing plan and note how the
engineer has created a hold-down path up to the roof diaphragm.
These systems can be complicated, so if anything is unclear I
notify the engineer and ask for guidance. To avoid confusion
between subs, I meet with our lead framer and foundation
foreman to discuss the plan and to note any changes.