How to Set Up an Air Compressor for Roofing Nailers and Cap Guns
Level, regulated, drained and the right hose for the run. Most nailer trouble starts at the compressor.
- Beginner
- 10 to 15 minutes
- Updated
The short answer
Set the compressor on level, dry ground, check the oil and drain valve, run the regulator to the pressure the nailer specifies (commonly 90 to 120 psi), and connect a hose sized for the run, typically 3/8 inch for short to medium lengths. Match couplers, add a water trap in cold or damp weather, drain the tank after use and keep the hose off sharp edges.
An air compressor is the quiet half of a nailing system. The nailer gets the attention, but the tool only works as well as the air it gets. Too little pressure and nails sit proud. Too much and they go through the shingle. A kinked hose, a mismatched coupler or a tank full of water will cause jams and misfires that look like a problem with the nailer.
For roofing you do not need a huge compressor. A single coil nailer or cap nailer uses relatively little air per shot. You need enough tank and pump to keep up with the rate you fire, a proper regulator and a hose that does not choke the flow. This guide covers the setup. For the tool itself, see how to use a roofing coil nailer, and for trouble, how to clear nail gun jams.
Tools
- Air compressor with a regulator and gauge
- Air hose, 3/8 inch for most runs
- Matching couplers and fittings
- Inline water trap or filter
- Pressure gauge for checking at the tool
- Extension cord rated for the compressor, if electric
Materials
- Compressor oil, for oil-lubricated pumps
- Air tool oil
- Thread tape for fittings
- Winter air line antifreeze or additive made for air tools
Safety first
- Never exceed the maximum pressure printed on the tool, the hose or the tank. Overpressure breaks fittings and can injure anyone nearby.
- Relieve the pressure and disconnect the tool before working on it, and unplug or shut down the compressor before servicing it.
- Drain the tank after use. Water sitting in a steel tank rusts it from inside, and a corroded tank can fail.
- Keep the hose out of walkways and away from edges where someone can trip, and never drag the compressor by the hose.
Step by Step
Step 1: Choose a spot and place the compressor level
A compressor that sits on a slope can starve the pump of oil and will vibrate and walk. Put it on a board or mat if the ground is soft. Keep it in the shade if you can, since heat makes it work harder. Point the exhaust and the noise away from neighbours and away from where people will be working.
Do not put the compressor on the roof, where it can slide or fall. Keep it on the ground and run the hose up.
Step 2: Check the oil, filters and drain valve
Oil-lubricated pumps have a sight glass or a dipstick. Top up with the oil type the manual specifies, not engine oil. Oil-free pumps need no oil but wear out faster. The air filter should be clean. A clogged filter cuts output and overheats the pump. The drain valve on the bottom of the tank must be closed, or the tank will not build pressure.
Step 3: Connect power correctly
An undersized cord drops the voltage and makes the motor overheat and trip. Use a cord with the gauge the compressor manual specifies, and keep it as short as you can. Keep the plug and cord out of puddles. Gas compressors must be used outdoors, never in a garage or enclosed space, because of carbon monoxide.
Step 4: Choose and lay out the hose
A 1/4 inch hose chokes the flow on longer runs and cuts the pressure at the nailer. A 3/8 inch hose is the usual choice for runs up to about 100 feet with a coil nailer. Longer runs lose pressure, so set the regulator a little higher and confirm the pressure at the tool. Every extra coupler and fitting also restricts flow.
Run the hose up the side of the ladder and along the ridge or a safe side of the roof, secured so it does not pull on the tool or slide off. Keep it away from the eave and from anywhere people walk. Never lay the hose across a walkway without a cover.
Tip: Use a whip hose of 10 to 15 feet at the tool end so the heavy main hose is not dragging the nailer.
Step 5: Match the couplers and add a water trap
Coupler types are not all interchangeable, and a mismatched plug can leak or fail to lock. Use one type across all the gear. Wrap threaded joints with thread tape, turned the right way, and check for leaks by listening or by brushing soapy water on the joints.
An inline water trap or filter near the compressor catches condensation before it reaches the nailer. It is especially useful in the wet Fraser Valley winters and on humid days.
Step 6: Set the regulator and verify the pressure at the tool
Most roofing coil nailers work in the range of 90 to 120 psi, and cap nailers have their own range. The label on the tool gives the maximum. Set the regulator to start at the lower end and adjust up. On a long hose the pressure at the tool will be lower than at the regulator, so check it. Never set the regulator above the tool's maximum pressure.
Turn the regulator knob only when the compressor is running and the tank is full, so you see the actual working pressure.
Step 7: Oil the tools and watch the compressor during the day
Many nailers are oiled, and a few drops at the start of the day keep the o-rings supple. Others are oil-free, so check the manual. Do not over-oil, which leaves an oily mist and stains shingles. A compressor that never stops running has a leak or is too small for the tool. Turn off, find the leak and fix it.
Step 8: Shut down, drain the tank and store
Water collects in the bottom of every tank. Open the drain valve slowly and let the water and air out. A tank that is not drained rusts from the inside out. Wipe the compressor and store it upright and dry. Coil the hose without kinks and check for cracks and worn spots.
Cold Weather Setup
In cold weather, moisture in the air line freezes in the fittings and the nailer and stops the flow. A water trap, a short warm-up, and air line antifreeze made for pneumatic tools all help. Drain the tank more often, and keep the compressor sheltered from frost and rain when not in use. Cold hoses stiffen, so uncoil them before they are pressurized. Cold oil is thicker, so use the oil weight the manual lists for cold starts.
How Much Compressor Do You Need?
Roofing nailers use a small volume of air per shot, so a portable compressor with a modest tank runs one or two guns. The tool manual lists the air consumption. For two nailers or a nailer plus a cap gun, choose a compressor whose rated output at 90 psi exceeds the combined demand, with a margin. A compressor that is too small runs constantly and overheats. One that is too large is heavy to carry.
Common Mistakes
- Setting the regulator above the tool's maximum. It damages the nailer and can be dangerous.
- Using a thin, long hose. The pressure at the tool falls well below the gauge reading.
- Never draining the tank. Rust forms and eventually weakens the tank wall.
- Mixing coupler types or skipping thread tape, which leads to leaks and pressure drops.
- Skipping the water trap in winter. Ice in the fittings stops the flow at the worst moment.
- Putting the compressor on the roof or dragging it by the hose.
When to Call a Professional
If the compressor trips breakers, leaks from the tank, runs without building pressure or has a pressure switch that does not shut off, stop using it and get it serviced. A damaged tank or a faulty safety valve is a real hazard.
For crew jobs with several nailers, a larger compressor and a manifold are a better answer than trying to stretch a small unit.
Fraser Roofing does free roof inspections across the Fraser Valley, from Hope to Abbotsford. See our Roof Replacement service or the towns we cover.
How to Set Up an Air Compressor for Roofing: Questions
What PSI should I set my air compressor to for roofing?
Set the regulator to the pressure the nailer specifies. Most roofing coil nailers run in the range of about 90 to 120 psi, but the label on the tool is the authority. Start near the low end and raise in small steps until nails seat flush, and check the gauge at the tool because long hoses lose pressure.
What size air hose do I need for a roofing nailer?
A 3/8 inch hose is the common choice for roofing, and suits runs of up to about 100 feet. A 1/4 inch hose restricts flow on long runs and lowers the pressure at the nailer. Use the shortest hose that reaches the work, and match couplers across the whole system to avoid leaks.
Why do you drain an air compressor tank?
Compressing air squeezes out water, and it collects in the bottom of the tank. Left in place it rusts the tank from inside, contaminates the air line and freezes in winter. Open the drain valve slowly at the end of each day to release the water and pressure, and let the tank dry.
Can I run a roofing nailer on a small pancake compressor?
Usually yes for a single coil nailer or cap nailer, because these tools use a small amount of air per shot. The compressor must reach the pressure the nailer needs and recover fast enough to keep up with your pace. If it runs almost constantly or pressure drops as you work, it is undersized.
How do you use an air compressor in cold weather?
Use an inline water trap and an air line additive made for pneumatic tools, drain the tank often and keep the compressor sheltered. Uncoil hoses before pressurizing because they stiffen in cold. Use the oil the manual recommends for low temperatures, and expect nailers to need a depth adjustment as shingles stiffen.
Related Guides
All Roofing Tools guides|The full How-To Library
This guide is general education. Always follow the product manufacturer's installation instructions, the BC Building Code and WorkSafeBC requirements, which take priority over anything written here.
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