Ties That Bind

Lightweight connectors give a house hidden strength.

As a contractor, I love it when I can show a client how to get top return on a minimum investment. Almost always, the advantage is in planning.

Take something as simple as connectors designed to hold the frame of a house together in high winds. This is something a lot of us in regions outside of hurricane territory were slow to embrace. But ask folks in Florida or the coastal Carolinas. They'll tell you about grand beach houses blown apart in big storms because roof systems, walls, and foundations weren't tied together properly.

Tie-downs and hold-downs are among the least expensive hardware items in a house. And because they're so easy to install at appropriate stages of construction, I think anyone building a house or an addition should insist on them.

Hurricane clips
This term now refers to just about any connector that ties in sections of a house's frame. But most builders mean the hardware used at the point where rafters or upper-story floor joists sit atop walls.

In normal conditions, gravity helps hold roofs and walls together. That's why many inland builders don't include the tie-downs. It's when powerful winds pry roofs upward that trouble begins.

I've seen storms peel roofs entirely off walls, exposing interiors as if they were dollhouses. Sometimes winds rip off roof systems and deposit them intact elsewhere. The problem is not in holding a roof together but in keeping it locked onto the walls and foundation.

The most common hurricane clip is a twisted metal strap with predrilled nail holes; one face of the strap is nailed to the roof support, the other to the wall top plate. These clips should be attached wherever rafters meet walls. The number of nail holes in the straps may vary, and you might not need to use every one. Local codes specify how many nails are considered adequate for each connector. Here's a tip: Don't overdo the nails. You increase the chance of splitting a stud or rafter with every extra nail.

Inside-corner connectors
These are variations on the typical hurricane clip. They're made for designs in which, instead of resting on the top of wall plates, the bottoms of horizontal roof beams butt directly into them from the side. What you need here is a strap that secures the right-angle connection between wall and roof beam. It looks something like a hinge frozen in a 90-degree position. Again, there are predrilled holes on each strap face. Consult local codes for the required number of nails in each strap.

Shear-wall connectors Builders in earthquake areas already know about this technique, but we're seeing more and more of these wall systems in Nantucket. Because a lot of modern house designs are so complex, architects and engineers like to use fortified interior walls for extra structural support. These are shear walls, framed with 4 by 4s and sheathed with plywood beneath the gypsum wallboard or other finish materials.

The idea is to create a wall that resists the domino motion of a structure under stress. Not only do we beef up the wall with fatter studs and plywood, we also anchor it with stirrup-like connectors at its base. The 4 by 4s sit in the metal stirrups, which are bolted straight through to the foundation. At the top of the wall, where it meets rafters or second-floor joists, we use standard hurricane clips. So the whole fortified system is tied in from foundation to roof.

The retrofit challenge How about homes built before tie-down hardware became common? Can you install clips and tie-downs after walls and ceilings are in place?

To do this right, you have to get beneath wall and ceiling coverings to the places where structural elements meet. This is no problem if you're doing an addition or major remodeling. But you'll need to weigh costs against benefits if you have to tear up your home to install hardware. I recommend that you never miss a reasonable opportunity to reinforce your house. It will protect your investment and perhaps your life.

Connect online
We don't endorse any particular kind of clip or connector, but one manufacturer, Simpson, has such a great Web site on the subject, we think it's worth pointing readers to it: wellconnectedhouse.com. Besides having great illustrations of how connectors work, the site offers terrific links to sites with info about housing codes.

If you want to see what one of the most hurricane-vulnerable areas in the country requires of new construction, check out Florida's recently updated building code.

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