Like many builders, we used to use hammer tackers to staple up housewrap, felt, and other siding and roofing membranes. Hammer tackers are fast, but they can cut through the material, the staple holes can leak, and foot traffic or wind can tear the material off the staples.

Using capped fasteners can eliminate those problems, which is one reason why many major manufacturers of housewrap and synthetic roofing underlayment now recommend or require them. Plastic caps increase a fastener's surface area, thereby increasing its holding power. As a result, the membrane is much less likely to tear out from underneath the fastener, especially when exposed to wind—even a light breeze can pressurize housewrap and underlayment, causing tears around staples and ordinary roofing nails.

We switched to hand-driven plastic-cap nails a few years ago to comply with the new manufacturer recommendations. The fasteners work well, but only a small number can fit into a nail bag, and hand-nailing is awkward and slow. Hoping to dramatically speed up the work, we bought a pneumatic Hitachi NV50AP3 coil cap nailer. That was almost a year ago, and so far, we've been happy with that decision.


We initially considered buying a pneumatic cap stapler, but quickly switched our focus to cap nailers because nails are more dependable in high winds and are approved by more synthetic-roofing underlayment manufacturers. Also, the most powerful cap-nailer models can drive longer fasteners.

Based on my research, we shortened the list to two options: the Bostitch N66BC and the Hitachi NV50AP3. The Bostitch can drive cap nails up to 2 ½ inches long, so it can be used to attach 2-inch-thick foam. It holds 300 coiled nails, but only one cylinder of 100 string-collated plastic caps, which means you have to reload the caps three times per nail coil.

The Hitachi, on the other hand, drives cap nails up to only 2 inches long but conveniently holds 350 coiled nails and a matching reel of 350 plastic or metal caps. Also, we've owned more than 20 Hitachi nailers during the past 13 years with almost no complaints, and the NV50AP3 is a third-generation model that has been on the market since 2005. Although the Hitachi cost about $180 more than the Bostitch, we bought the Hitachi.


We've used the NV50AP3 to install Tyvek HomeWrap, ¼-inch fan-fold foam, #30 roofing felt, and RhinoRoof synthetic roofing underlayment—driving more than 30,000 1 ¼-inch-long plastic-cap nails. Hitachi sells them by the case for about $52, packing 2,800 caps and nails into a sturdy cardboard box with dividers that keep the rolls from uncoiling.

I'd estimate that using the tool is at least five times faster than hand-nailing. Once we dial in the driving depth, the NV50AP3 consistently sets nails to the desired depth even in foam, which is hard to do when hand-nailing. Although we've used the tool in temperatures down to 15°F, it has misfired only occasionally—when a cap hadn't completely severed from the roll. It was easy to clear the problem and get back to work.

As advertised, the tool is well-balanced and feels lightweight. The cap magazine is bulky but doesn't prevent us from nailing into tight spots. The cap and nail magazines are both easy to load one-handed while we're working out of a nail apron on a roof or ladder, holding the tool with the other hand. We also appreciate the translucent magazine covers, which let us check the contents at a glance. You can easily adjust the exhaust vent so it doesn't blow air in your face, and a simple switch toggles between bump and sequential firing.

On the downside, the tool doesn't have a rafter or belt hook, and you have to install your own 3/8-inch NPT male plug at the air inlet. But overall, Hitachi's cap nailer has been a great tool that's paying its way in labor savings.

—Josh Dunlap is production manager forConsolidated Design & Construction Group, a residential design/build remodeling contractor in St. Louis.