When the Ridgid R84040 18-volt adhesive/caulk gun arrived at the office, my crew and I shared the same thought: Just because you can make something doesn't always mean you should. But while that adage applies to many things, our test proved the R84040 isn't one of them. It quickly earned our approval.


Run mondo beads from 30-ounce construction adhesive tubes onto framing or smooth caulk beads from 10-ounce tubes onto trim with the R84040.


The Ridgid R84040 is designed to easily handle 30-ounce construction adhesive tubes and 10-ounce caulk tubes–a very nice feature.

To dispense either size, open the adhesive or caulk normally (using the convenient puncture stick located on the tool body), then load it. Next, flip off the safety lock, set the variable-speed selector, and pull the trigger. The R84040 applies pressure on the plunger at the selected rate and pushes as long as you pull the trigger. When the tube is empty, the tool automatically shuts off. Switching between tube sizes doesn't require any special change-outs or work.

Running different beads with the tool–from mega 3/8-inch subfloor runs to a delicate bead along base molding for paint–was easy using the tool's power setting. The tool provides consistent results from start to finish and the flow stops with no drips.

Battery Power

Ridgid designed a low-profile battery for the R84040, but it accepts any 18-volt Ridgid battery. The dispenser ships with one battery, which worried me, but the company says you can run 250 30-ounce tubes on one charge. With one tube gluing about four sheets of plywood, that means the R84040 squeezes enough glue in one charge for 1,000 sheets. I'd run out of juice long before this tool would. On site, the tool had no problem keeping up with my framers.


The carriage and plunger can be wiped down easily or you can dip the working end of the tool in a bucket of solvent. Nice.



The R84040's framing guide makes spreading glue on joists much easier.

The R84040 comes with a handy joist follower attachment. The 2-1/4-inch-wide foldout guide enables you to keep the tool centered on a joist or truss. The tool also ships with a well-made tool bag for the charger and battery. The tool itself hooks onto the outside of the bag, helping to keep glue off the charger and battery.


At $149, it costs about three times as much as a standard manual caulk gun, but this well-built tool provides production efficiencies, especially laying subfloor adhesive, and Ridgid's excellent three-year limited service warranty, lifetime service agreement, and 90-day satisfaction guarantee make me very comfortable about the investment. This tool will find a home on my jobsites.

Ridgid R84040 battery-powered caulk/adhesive dispenser: $149. 800-474-3443.

–Michael Davis is a contributing editor for Tools of the Trade.