Coil roofing nailers are the most abused tools on my jobsite. They withstand blistering rooftop heat under summer sun, take two-story high-dives onto frozen mud in winter, and endure constant grinding as I drag them across 10-grit shingle granules. And that doesn't even account for the grime that builds up inside and outside the tools from working in this merciless environment. So, to say roofing nailers have a tough job is an understatement.
I field-tested 11 nailers–the Bostitch RN46, Craftsman 18180, DeWalt D51321, Hitachi NV45AB2, Makita AN451, Max CN450R, Paslode 3175-RCU, Porter-Cable RN175A, Ridgid R175RNA, Senco 455XP, and Spotnails VRN45–putting them through their turns fastening heavy laminated (aka architectural or dimensional) shingles in cold and moderate weather conditions. While I looked at operational functions (power and recoil, depth-of-drive adjustments, driver blades, and exposure gauges) and ergonomic and durability features (reloading nails, handling, and wear guards), it was power, recoil, and speed that mattered most. At the beginning, middle, and end of the day, I need a nailer that skips across shingles with minimal recoil and flush-drives every nail–every time.
The Driving Force
Power and Recoil. I don't have the gear to objectively test a nailer's driving power, so I gauge it with my hammer–the more I have to take my hammer out of my loop to pound down proud heads, the more air pressure I know a nailer needs. Since all the tools in the test specify a pressure operating range of 80–120 psi, I set my compressor with an output regulator to 100 psi. I then ran the tank at 110–130 for constant air output, which leveled the playing field for all the nailers. Most of my roofs are sheathed with 5/8-inch AdvanTech–an exceptionally dense product–and I typically install 35-year or better laminated shingles. Like most roofers, I position the shingles and bounce-nail across each course. My speed is greatly influenced by how fast a nailer cycles and how little recoil it has. To maintain top speed, I want little or no recoil so the tool skips across the surface rather than jumping after every nail.
The Max, Hitachi, Senco, DeWalt, Spotnails, Porter-Cable, and Bostitch all drove nails consistently with little recoil. The Makita and Ridgid were noticeably less powerful with medium recoil, leaving occasional proud nail heads. The Craftsman and Paslode needed more power for my roofs. Even with the depth-of-drive dialed to the max and the compressor regulated at 100 psi, the Craftsman couldn't set all the nails on a full row of shingles and the recoil was too strong while bump-nailing. The Paslode recoiled a little less but was also underpowered, and without a depth adjustment there was no way to increase drive depth to compensate.
Drivers. Drivers are among the most expensive replacement parts on a roofing nailer, and as they wear down nail heads don't set flat. The good news is that you can grind a driver two or three times before it becomes too short and needs replacing.
Drivers come in two flavors: crescent and full-round. The Bostitch and Max tools have full-round drivers that make full contact with the nail head. The remainder of the field use crescent-shaped drivers, which only make contact with one-half to three-quarters of the nail head (depending on model). When nailing into dense material, crescent drivers sometimes bend the nail head and leave an edge sticking up. That nail head can cut into the shingle above or prevent it from sealing securely to the row beneath. The bent edge problem was exacerbated when I used generic nails and also was worse on nailers with the largest hollow in the driver: Makita and Craftsman.
Depth Adjustments. At 7 a.m. on one of my test days it was 45 degrees. The shingles had been chilling all night and they were stiffer than cold pizza. It required all the nailers' muscle to drive all nails flush and seat the shingles on the deck. But by noon it was 85 and sunny, the shingles were as soft as lasagna, and the nails were starting to punch through. Years ago I'd have had to climb down to the compressor and adjust air pressure or connect an in-line regulator. Today most roofing nailers have depth-of-drive adjustments, so no matter what the temperature or roof sheathing material, I can tweak a knob on the tool and get a flush-set with nearly every nail.
The Max, DeWalt, Senco, Ridgid, and Porter-Cable have easy-to-turn thumbwheels right beneath the trigger to dial-in depth. These five tools were excellent–I liked them all. Since the thumbwheels are away from the "business" end of the nailer, there's no fear of an ill-timed misfire doing you bodily harm.
The Hitachi has a narrow-diameter wheel that's tricky to twist. The action of squeezing pressure on the small wheel in order to pull it against the spring pressure while turning it is awkward for fat/numb-fingered guys like me.
Makita's adjustment wheel is front-located on the upper right side of the nose and has stepped adjustments. Craftsman's is front-located, too, just above the contact tip. Bostitch mounted an adjusting dial right on the front of the nose that locks into positive stops. Spotnails' drive-depth adjustment requires two small crescent wrenches (not supplied), so even though it works, it's unlikely most workers would bother. The Paslode has no adjustment.