They hold, straighten, and align, and even the best one you can buy costs less than what you’d pay a helper for half a day

Mention clamps, and people tend to think of shop work where pieces of lumber are glued together or bent to make furniture. Though clamps may not be the first tools that come to mind for building decks and other outdoor projects, that is what I first used them for. I had no helpers, but I did have a standard Irwin Quick-Grip clamp — and it held up a lot of lumber.

As soon as I realized how helpful clamps could be, I started buying them in all different sizes. I use the 8- and 16-inch sizes the most, but larger ones do come in handy from time to time, say to clamp 2x12 joists to a 2x12 beam. Advertised as providing 500 pounds of force, the newer Irwin clamps are even stronger and more durable than the older models, and the trigger need not be squeezed all that hard to achieve maximum grip. It’s amazing what they can hold, and I’ve never had one give out because of the load.

One caution about clamps: They are not a substitute for structural connections. If I’m using a clamp to hold a support post to a beam, for instance, I drill and bolt the assembly before standing on it.

George Karsadi owns GLK Custom Decking in Alexandria, Va.

Putting Clamps to Work

I use clamps in dozens of ways that save me time and energy while making my projects look cleaner and more accurate. The most obvious would be to hold two workpieces together, such as a post and a beam that I’m drilling for bolts. Clamps also work great for aligning things, like newel posts or the pieces of a built-up beam. Many times driving a fastener opens up the joint it’s meant to close, but not if you clamp the joint first. And clamps can free up a helper from holding things for you, so his or her time can be spent more productively.

Clamps secure a post and beam prior to drilling and bolting. Another way to line up beam members is to clamp them to a perpendicular joist. One clamp draws diagonally to align the members of a beam. The second clamp is just snugged in place, ready to be tightened when the beam is lined up. Clamp temporary posts to stringers so the concrete landing can be poured exactly in place. A couple of hammer taps will level out adjacent newels. Clamping material together prior to nailing yields tighter joints. Rim joists often need to be tweaked into alignment. Clamp the subrail to the newels, and toenail from behind to give your rails a hidden-fastener look. Clamp the cap rail in place, then secure it with pocket screws or toe screws from below. Place the clamp’s jaws flat on both surfaces to flush up a miter joint before fastening. Composite decking is usually straight, while the 2x4 used for subrail is not. Clamps align the two prior to fastening.