HDQ8 holdowns are required on both ends of a shear wall and connected to the end stud or post because an earthquake has the ability to shake a shear wall back and forth and exert uplift forces on both ends, one end at a time. With the added resistance from holdowns, the post is better able to resist the tension load from uplift as well as the simultaneous compression load at the opposite end of the shear wall.

While there are no prescriptive requirements in the Building Code for the installation of holdowns, an architect, engineer or contractor will have a good idea of when and where they are necessary.

When HDQ8 holdowns connect an upper and lower wall through a floor they generally come in pairs – one for above and for below. This allows uplift forces to be transferred from the wall above to the wall below through the threaded rod that has been bolted to the holdowns.

Not every uplifting experience is a welcome one, and with Simpson Strong-Tie HDQ8 Holdowns you’ll be able to filter out the seismic variety.