How do you measure for gutters?

Step 1: Find the runs

Gutters go on the eaves, the level edges of the roof where water drips off. Gable ends, the sloped edges, do not get gutters. Sketch the house from above and mark each eave, including porches, bay windows and garage roofs.

Step 2: Measure each run

• On a one-story house, measure along the fascia from a ladder, or measure the wall at ground level and add the overhang at each end.
• Where the gutter wraps a corner, measure each side to the corner and note it as an inside or outside corner.
• Add a couple of inches per run for end caps and trimming.

Step 3: Count the fittings

• Inside and outside corners.
• End caps, two per straight run.
• Outlets, one per downspout.

Step 4: Plan and measure downspouts

Mark downspouts at the ends of runs and below valleys, roughly one per 30 to 40 feet of gutter. Measure from the fascia to the ground at each, then add elbows: typically two at the top to bring the pipe back to the wall and one at the bottom to turn water away.

Step 5: Note the size

Record whether the existing gutters are 5 inch or 6 inch across the top, and whether the downspouts are 2 by 3 or 3 by 4 inch. Large or steep roof planes may call for upsizing.

Sectional gutters are sold in fixed lengths, so convert footage to pieces with overlap. Seamless gutters are formed to each run's exact length. See gutter sizing, seamless gutters and guards and how roofers measure a roof.