In October 2023 I inspected a 1979 house on a wooded lot above Oswego Lake, and the roof was the reason the buyer had called me. It was cedar shake, thirty-some years old, and shaded on its north slope by three Douglas firs that had never been limbed. From the ground, with binoculars, it looked tired but intact. The drone told a different story in about eleven minutes of flight time, and the footage is what the buyer used to negotiate and what the roofer used to quote. This is how I shot it and what showed up.
Why I fly before anyone walks a cedar roof
Cedar shake is one of the few roof types I refuse to walk on an inspection. Old shakes split under a boot, moss makes them slick, and on this house the pitch was 8:12 with a 20-foot drop to a stone patio. A drone gets the camera 15 feet above the ridge without anyone leaving the driveway, and it does it in the same light for every slope. That last part matters more than people expect. When a roofer later walks the roof and finds something my footage did not show, a timestamped, continuous record of every square foot settles the question of whether it was there on inspection day.
I fly a small quadcopter with a 1-inch sensor for this work. Lake Oswego sits a few miles outside Portland’s busiest airspace, but I still check the map before every launch. The tree canopy was the real hazard here, not aviation rules.
The flight pattern that catches shake problems
Shakes fail in ways that are hard to see from straight overhead. Cupping, splitting and lifted butts read as texture, and texture needs a low sun angle and an oblique camera. My pattern for a roof this size, roughly 2,400 square feet of roof surface, runs like this:
- One orbit at about 40 feet above the ridge with the camera tilted 30 degrees down, recording 4K at 30 fps. This is the context pass and it takes two minutes.
- Straight-down stills at 25 feet, 70 percent overlap, in a lawnmower grid. About 60 frames for this roof. These become the orthomosaic if anyone needs to measure.
- Slow oblique passes along each slope at 12 to 15 feet above the surface, camera at 45 degrees, flying parallel to the courses. This is where the useful footage comes from.
- Hover shots at every penetration: chimney, two plumbing vents, a skylight, and the valley where the garage roof meets the main house.
I shoot the video at 1/60 s with a neutral density filter to hold the shutter there, ISO 100, and a flat picture profile so I can pull detail out of the shaded slope later. Exposure gets locked on the roof itself, not on the sky, or the shakes go black under the firs.
What the footage actually showed
The south slope, in full sun, was gray, weathered and mostly sound. The north slope was a different roof. In the oblique passes, moss mats an inch thick covered maybe 40 percent of the surface, holding water against the wood. Where the moss had been scraped in some earlier year, the shakes underneath had cupped hard enough that I could see the felt interlayment in three spots. Around the chimney, the step flashing had lifted on the uphill side and a shake had slid a full 4 inches out of its course. None of that was visible from the ground.
The valley shot was the one that settled the deal. Fir needles had packed the valley 3 inches deep for its full 14-foot run, and the footage showed a dark, wet stain fanning out onto the garage roof below it. I pulled a still from the video, dropped a note on it, and put it in the report with the rest.
Handing the footage to the people who quote the work
Raw drone files are useless to a buyer. What I deliver is a 90-second edit per slope with on-screen labels, full-resolution stills organized by roof plane, and the untouched originals on a shared drive. File names carry the address, the date, and the slope.
The buyer sent the north-slope clips and the valley stills to a Lake Oswego roofing contractor, who priced a full tear-off and replacement from the footage, then confirmed it with a 20-minute site visit. Replacement quotes for a cedar shake roof this size in the Portland area ran between $38,000 and $55,000 depending on whether the owner went back to cedar or switched to synthetic shake. The seller credited a portion at closing, and the footage was the only document both sides agreed on.
Frequently asked questions
How much does a drone roof survey cost before a reroof? A standalone survey with edited clips and stills typically runs $150 to $400 in the Portland metro area. Many home inspectors add it to a full inspection for $75 to $150 more; roofers often fly during a quote visit at no additional charge.
Can a drone see moss damage under cedar shakes? Not directly, but oblique footage at 12 to 15 feet in low sun shows cupping, splits, lifted butts and exposed felt, which are the symptoms that follow long-term moss cover. A roofer will still need to lift a few shakes to confirm the condition of the felt and sheathing.
What time of day is best to fly a shaded roof? Overcast weather gives the most even light across sun and shade slopes. If it is sunny, fly when the sun is 30 to 45 degrees above the horizon and lock exposure on the roof surface rather than the sky.