Ties That Bind
Lightweight connectors give a house hidden strength.
As a contractor, I love it when I can show a client how to gettop return on a minimum investment. Almost always, the advantage isin planning.
Take something as simple as connectors designed to hold theframe of a house together in high winds. This is something a lot ofus in regions outside of hurricane territory were slow to embrace.But ask folks in Florida or the coastal Carolinas. They'll tell youabout grand beach houses blown apart in big storms because roofsystems, walls, and foundations weren't tied together properly.
Tie-downs and hold-downs are among the least expensive hardwareitems in a house. And because they're so easy to install atappropriate stages of construction, I think anyone building a houseor an addition should insist on them.
This term now refers to just about any connector that ties insections of a house's frame. But most builders mean the hardwareused at the point where rafters or upper-story floor joists sitatop walls.
In normal conditions, gravity helps hold roofs and wallstogether. That's why many inland builders don't include thetie-downs. It's when powerful winds pry roofs upward that troublebegins.
I've seen storms peel roofs entirely off walls, exposinginteriors as if they were dollhouses. Sometimes winds rip off roofsystems and deposit them intact elsewhere. The problem is not inholding a roof together but in keeping it locked onto the walls andfoundation.
The most common hurricane clip is a twisted metal strap withpredrilled nail holes; one face of the strap is nailed to the roofsupport, the other to the wall top plate. These clips should beattached wherever rafters meet walls. The number of nail holes inthe straps may vary, and you might not need to use every one. Localcodes specify how many nails are considered adequate for eachconnector. Here's a tip: Don't overdo the nails. You increase thechance of splitting a stud or rafter with every extra nail.
These are variations on the typical hurricane clip. They'remade for designs in which, instead of resting on the top of wallplates, the bottoms of horizontal roof beams butt directly intothem from the side. What you need here is a strap that secures theright-angle connection between wall and roof beam. It lookssomething like a hinge frozen in a 90-degree position. Again, thereare predrilled holes on each strap face. Consult local codes forthe required number of nails in each strap.
Shear-wall connectors Builders in earthquake areas alreadyknow about this technique, but we're seeing more and more of thesewall systems in Nantucket. Because a lot of modern house designsare so complex, architects and engineers like to use fortifiedinterior walls for extra structural support. These are shear walls,framed with 4 by 4s and sheathed with plywood beneath the gypsumwallboard or other finish materials.
The idea is to create a wall that resists the domino motion of astructure under stress. Not only do we beef up the wall with fatterstuds and plywood, we also anchor it with stirrup-like connectorsat its base. The 4 by 4s sit in the metal stirrups, which arebolted straight through to the foundation. At the top of the wall,where it meets rafters or second-floor joists, we use standardhurricane clips. So the whole fortified system is tied in fromfoundation to roof.
The retrofit challenge How about homes built before tie-downhardware became common? Can you install clips and tie-downs afterwalls and ceilings are in place?
To do this right, you have to get beneath wall and ceilingcoverings to the places where structural elements meet. This is noproblem if you're doing an addition or major remodeling. But you'llneed to weigh costs against benefits if you have to tear up yourhome to install hardware. I recommend that you never miss areasonable opportunity to reinforce your house. It will protectyour investment and perhaps your life.
We don't endorse any particular kind of clip or connector,but one manufacturer, Simpson, has such a great Web site on thesubject, we think it's worth pointing readers to it: wellconnectedhouse.com.Besides having great illustrations of how connectors work, the siteoffers terrific links to sites with info about housing codes.
If you want to see what one of the most hurricane-vulnerableareas in the country requires of new construction, check out Florida'srecently updated building code.