Hold-downs are connections commonly used for foundations, wall-to-wall connections, wall-to — concrete connections, and wall or floor-to-drag strut. Hold-downs are also called anchor downs and tie-downs. They can be difficult to install, but if you plan ahead and install as you go, the job is more manageable. Hold-downs that attach walls to the concrete foundation are typically attached to bolts already in the concrete. These bolts are generally set in place by the foundation crew. Sometimes they won’t be set in the right place.
You will want to locate the hold-down as close to the end of the shear wall as possible. If the bolt is already in the concrete, you will have to locate a hold-down on either side of the bolt. When considering the location, be aware of how it relates to what is on the floor above it; you don’t want, for example, the hold-down coming up in a door or window.
You should also allow enough space to install and tighten nuts and bolts.
Although it is common to wait until the building is framed to install the hold-downs, waiting can also present problems, such as studs that are already nailed in place where you want to install the holddowns, sheathing that is hard to nail because it may be on the exterior of a second or higher floor, and possible pipes or wires running in the stud cavity.
It is helpful to install the hold-down studs as you build the walls. The layout framer should detail the hold-down studs while detailing the wall plates, and should also drill the plates for the anchor bolt or the threaded rods. If an upper floor is involved, the framer should also drill down through the subfloor sheathing and the top and double plate of the wall on the floor below. The wall builder should drill the
studs before nailing them into the wall. When the wall sheathing is installed, make sure it is nailed to the hold-down studs using the same nailing pattern that was used for edge nailing. (See “Hold-Down Nailing" illustration.)
Install the hold-downs and bolts, and washers and nuts, as soon as possible. Note, too, that when installing hold-downs after the walls are built, it is more productive to do an entire floor at one time. If the anchor bolts in the concrete do not extend high enough, a coupler nut can be used to extend the length. (See “Coupler Nuts Can Extend Anchor Bolts" illustration.)
As noted previously, the holes drilled for the bolts attaching the hold-down to the studs should not be more than!/іб” bigger than the bolts. However, it is acceptable to oversize the holes you drill for the threaded rod that passes between the floors. This will make installation easier without affecting
strength. (See “Drill Hole Size for Hold-Downs" illustration.)
With all nail-on connection hardware, it is important to use the right size nail. Hardware manufacturer’s catalogs indicate nail size appropriate for each piece of hardware. Most catalogs also give some options for nail use.
Hold-downs
Drill Hole Size for Hold-Downs
Drill holes no more than /16" bigger than bolts to maintain strength.
