Ask to See the Chalk Lines Before the Shingles Go On

A shingle roof is only as straight as the first few rows laid under it. Most homeowners never see those rows, because by the time the roof is finished the lines are hidden under the last course at the ridge. Before the first bundle is opened on the deck, a careful crew snaps chalk lines across the underlayment so every course sits level and the shingle pattern lines up from eave to ridge. Asking to see those lines before the shingles go on is one of the few checks a homeowner can make while the work is still open to view.

What a chalk line does on the deck

A chalk line is a straight mark snapped with a reel of string dusted in colored chalk. On a roof, crews use the lines to set the courses, which are the horizontal rows of shingles. Each course has to overlap the one below it by the amount the shingle wrapper specifies, called the exposure. If the first row starts a little off level, every row above it inherits the error, and the drift only becomes visible when the roofer reaches the far end of the slope and the last row no longer meets the rake or the valley the way it should.

Chalk lines also help with vertical alignment. Many architectural shingles have a pattern that repeats across the course, and a crew that snaps a line for those spacings keeps the pattern from wandering. On a long run of roof, a few inches of wander can leave the pattern visibly crooked from the street, even though each shingle is individually fastened correctly.

Why the lines matter more on St. Louis roofs

St. Louis roofs go through freeze and thaw cycles every winter, and they take hail in the spring and wind in the summer. The shingles that come off a roof after a storm are rarely the ones that look worst. The new roof has to lie flat enough to shed water through every spring thaw, and a course laid off line can leave a small step where one row sits higher than the one beside it. Water finds those steps. A wandering course also puts more stress on the nails in the rows where the overlap is short.

Older houses in the county often have decks that are not perfectly flat, and the chalk line is how a crew works around that. A good crew will check the lines against the eave and the rake, and will re-snap a line if the deck has a dip. A roofer who skips the step and starts laying from the eave by eye is not necessarily doing bad work, but the homeowner has no way to see the difference until the roof is complete.

What to compare between bids

Chalk lines rarely appear as a line item on a proposal, so they will not show up when you compare totals. They show up in how the roofer describes the job. Two proposals can have the same square count, the same underlayment, and the same shingle, and still differ in whether the crew plans to snap lines on every course or only at the start. Ask each roofer directly which of these they do, and write down the answer next to the price.

• Whether the crew snaps chalk lines on the underlayment before the first shingle is laid
• Whether lines are snapped for the exposure printed on the shingle wrapper, and whether that exposure is checked before work starts
• Whether the crew re-snaps lines where the deck dips, around chimneys, or along valleys
• Whether the roofer will let you see or photograph the lines before the shingles are fastened

Each answer should be a plain yes or no, and a roofer who is doing the work carefully will usually answer without hesitation. A vague answer about "our process" is worth a follow-up question, because it means the homeowner cannot tell from the proposal what the crew will do.

What to ask, and when to look

The right time to look is the morning the underlayment goes down and before the first bundle is opened on the deck. Ask the crew lead to show you the chalk lines on the eave side, then walk the rake to confirm the lines run parallel. You do not need to climb onto the roof to see this. From the ground with a ladder at the eave, or from a neighbor's yard, you can often see the chalk through the underlayment on a bright day, and a photo from your phone works well for your records. Keep the photos with the rest of the job file.

If the crew is not ready to show you the lines, ask when they will be. A crew that has snapped lines will have them ready to show. A crew that has not may be laying from the eave by eye, and that is worth knowing before the shingles are fastened, not after.

Shingle brand and the chalk line

Keys Roofing installs Atlas and Malarkey shingles only. Both brands print exposure and installation instructions on their wrappers, and those are the numbers the chalk lines should follow. If you are comparing bids and one roofer proposes a different shingle, ask which exposure that shingle uses and whether the crew has the same spacing marked on the deck. A mismatch between the shingle and the lines is easy to avoid and hard to fix once the roof is covered.

A written scope should name the shingle line and the wrapper exposure. If it does not, add that to your list of questions before you sign. The scope is the document you will hold when the roof needs its first repair, so the detail is worth getting on paper now.

If the lines look wrong

If you see a line that does not run parallel to the eave, or a course that sits visibly higher than the one beside it, say so to the crew lead on the day, and ask for the course to be checked. A reputable roofer will want to know, and will not treat the question as an insult. Photograph the spot and note the time. If the problem is not corrected while the roof is open, it becomes much harder to correct after the last row is down.

For questions about your roof, the Keys Roofing office can be reached at (314) 220-2333. Ask for the crew schedule and the chalk line check together, so both are on the calendar for the same morning.