Ask Each Roofer How Often Their Nail Gun Is Calibrated

A roofer's nail gun decides more about your roof than most homeowners expect. Set too hard, the gun drives the nail through the shingle's mat and leaves a dimple that holds no water and tears under wind. Set too soft, the nail head sits proud of the shingle, and the tab lifts in the next storm. St. Louis puts real load on that fastening. The freeze and thaw cycle works the shingles every winter, and hail season can arrive with one warm front and a hard wind behind it. The gun setting is one of the few details in a roof job that can be checked on the day it is done, so it is worth asking about before you choose a roofer.

Why the gun setting belongs in the comparison

Shingle manufacturers print nailing instructions on the wrapper and in the install sheet. Those instructions give the nail count per shingle, the nail placement, and the depth the head should reach. A crew can follow the words on the wrapper and still miss the depth, because the depth depends on air pressure, the hose length, and how the gun has been adjusted over the past few weeks. Air pressure drops as the compressor runs down, and a gun set on a cold morning can drive differently by noon. A roofer who calibrates at the start of each day and again after a break is working to a fixed standard. A roofer who sets the gun once and leaves it alone is hoping the number holds.

Keys installs Atlas and Malarkey shingles only, so the nailing instructions a Keys crew follows come from those two manufacturers. Ask each roofer you compare to name the shingle line they plan to install and the nailing pattern printed for that line. If one roofer can name the line and the other cannot, that is a useful difference before any price is discussed.

Roofer comparison

Put the answers side by side in a short table on one sheet. Give each roofer one row and three columns: how often the gun is calibrated, who does the check, and whether the check is written down. A roofer who answers with a time, a name, and a record is describing a process. A roofer who answers with a general sentence about careful crews is describing a hope. Write the words they use, not your summary of them, so you can read the answers back to them later if the job changes hands.

Ask whether the check is done with a test nail in a scrap shingle, a depth gauge, or by eye on the first course. A test in scrap gives you a direct measure. A check by eye is still a check, but it depends on the person looking. Ask whether a foreman signs off the first course on each slope before the crew moves to the next one. That step catches a drifting gun before it has set a few hundred nails in the wrong depth.

What it costs

Calibration is usually a few minutes of crew time each morning, and most roofers carry it inside labor rather than as a separate line. That is the normal case, and it is worth confirming in writing rather than assuming. Ask whether the price includes the gun, the hose, the compressor, and any replacement gun if the first one fails on your roof. A worn gun that leaks air or fires inconsistently costs time and nails, and the question of who pays for that repair belongs in the bid before the first course goes on.

Ask whether the bid carries a line for a second test or a crew reset if the first inspection finds the nails are set wrong. Some crews reset the gun and re-check. Others pull the nails and renail the course. Those are different amounts of work, and the bid should say which one applies. A roofer who has thought through the answer will name it without hesitation. A roofer who has not may need a day to find out, and that gap is a fair thing to weigh.

What to ask

1. How often does the crew check the gun setting, and at what points in the day?

2. Who on the crew does the check, and does the foreman sign off the first course on each slope?

3. Is the check written down, and can I see the log for a finished job?

4. What depth does the nail head need to reach, and where does that number come from on the wrapper?

5. What happens to the nails already set if the gun is found to be out of spec after part of the roof is done?

6. Is the cost of a worn or failing gun included in the bid, and who replaces it?

Send the same six questions to each roofer in writing, and note the date and time each reply arrives. Specific, dated answers are easier to hold a roofer to than a phone conversation you may remember differently a week later. If an answer stays vague after a second request, call the office at (314) 220-2333 and ask the question again by phone, then write down what you were told and when. The point of the exercise is not to catch a roofer out. It is to find out whether the crew that will be on your roof has a standard it can name, and whether it keeps to that standard on the day that matters.