How many feet of lights your roofline needs, and how to measure it

The short answer

You need as many feet of lights as the roof edges you plan to light, measured along each edge rather than along the wall below it. For most houses that means the front roofline: the main eave, both rakes of any gable that faces the street, and the garage. Around here a two-story colonial usually needs 120 to 180 feet of lights across the front, and a ranch needs 60 to 80.

Those ranges are a starting point, not your number. A side-entry garage, a second eave over the porch or one more gable can push two neighbors far apart, so measure your own house before you buy a strand or ask for a price.

Below are three ways to get there: a tape along the ground under the eave, a cross-check against houses like yours, and one photo in the LightCast measuring tool. Three shorter guides go deeper on each step: the best photo for measuring your roofline, how to measure a roof peak, and getting an estimate online.

Lit feet vs total roofline

• Total roofline is every roof edge on the house: the front, both sides, the back, porch roofs, dormers and the garage. The full perimeter is always much larger than what the street sees.
• Lit feet are only the edges you choose to light. For most owners that is the street face, sometimes a side elevation on a corner lot, rarely the back.

Lit feet is the number that matters, whether you are shopping or pricing. LightCast prices a permanent install at $22–34 per lit foot with nothing due in later years, and leases a seasonal C9 display at $18–32 a foot per season. Neither charges for an edge you leave dark, though the seasonal lease carries a minimum of $595.

What goes into lit feet:

• Level eaves, measured at the outer edge of the roof from corner to corner, including the overhang past each wall.
• Rakes, the sloped edges of a gable, measured along the slope from eave to peak.
• The garage, whether it shows the street a short eave or its own gable.

What does not count: stretches you skip, the back of the house, and the lead from the outlet to the start of the run. For how lit feet become a price, see what permanent lights cost per foot.

Ground method: tape along the drip line

The drip line is the line on the ground directly below the outer edge of the roof. On a house without gutters you can often see it as a worn strip in the mulch or a row of splash marks in the stone. On a house with gutters it sits under the front lip of the gutter. Measure along it and you get the true length of the eave, which is longer than the wall because the roof overhangs at each end.

You need a 100-foot tape or a measuring wheel, a helper, and two or three stakes or bright stones. No ladder.

1. Choose your edges from the street. Stand where guests park and write down every line you want lit: upper eave, lower eave, front gable, garage.
2. Mark each end on the ground. Stand under a corner of the eave and sight straight up to its outer edge, or have your helper line you up from the curb. Set a stake at that spot, then do the same at the other end.
3. Run the tape between the marks. Keep it straight and parallel to the house. Walk it around shrubs rather than draping it over them, since every sag adds feet that are not there.
4. Work around what blocks the line. Where foundation plantings, a deck or a stoop make the drip line impossible to walk, measure the wall instead. Then measure the overhang at a clear corner, from the wall out to your stake, and add it at both ends.
5. Write every run down separately. Upper eave, lower eave, garage eave and the width of each gable each get their own line. Gables need an extra step, and separate runs map neatly to zones later.
6. Add the runs and round up to the next 5 feet.

A second-story eave with a porch roof under it drops its drip line onto that lower roof, not the lawn. On most colonials the upper wall sits directly over the lower one, so the ground-floor front wall plus both overhangs gives you the upper run. If your second floor juts out past the first, measure from the corners of the upper wall instead. Where a garage or bay steps forward, measure the house wall behind it.

Do this in October if you can. Once snow covers the beds, the drip line disappears and stakes will not go into frozen ground.

Adding gables without the math

A gable is where most measurements go wrong. Each sloped rake runs longer than half the gable's span on the ground, and the steeper the roof, the bigger that gap. A steep Tudor-style front gable carries far more footage than its width suggests, while a shallow garage gable adds only a little.

From the ground, set a stake under each bottom corner of the gable, tape the width between them, and write it down with a note: shallow, medium or steep. Count the peaks while you are there, and note any valley where two roofs meet.

Turning that width into rake length depends on the roof pitch, and it has its own guide: measuring gables and peaks for lights walks through finding your pitch and converting it. If you only want a planning number tonight, add the width once and then add to it: the pair of rakes on a 6/12 roof runs about an eighth longer than the width, and on a steep 12/12 front gable about two-fifths longer. The peak count matters too. Each peak means extra cuts and more time at height, which moves a house up within the price band even when the footage barely changes.

A hip roof is the easy case: no rakes, just an eave that wraps each corner.

A sanity check by house type

Once you have a total, hold it up against houses like yours. Our city pages for Macomb and Oakland County list the same six house types, each with one front roofline range, and the table names a city page where you will find each type.

Two quick checks catch most mistakes:

• Count garage doors. Use the double door as a 16-foot yardstick (a single one is 9). From the street, estimate how many double-door widths fit along your main eave. Five of them is about 80 feet. If your tape says 150, go back and look.
• Look at your gutter paperwork. If your gutters were installed or replaced, the invoice often lists linear feet. Gutters follow the level eaves, not the rakes, so if the invoice breaks out runs by side, the front runs should sit close to your eave total.

A total well outside your range usually means a rake counted at its flat width, a wall measured without overhangs, or part of the back creeping into the list.

With a checked number you can read a price straight off our table. Permanent lighting on a 100-foot front comes to $2,200–$3,400, paid once; leasing C9s for that front is $1,800–$3,200 per year. Measure 150 feet and permanent becomes $3,300–$5,100, against a lease of $2,700–$4,800 per year. The price table and 5-year calculator run the rest of the rows side by side.

Or measure it from one photo

If the beds are overgrown or you would rather skip the tape, a photo gets you to the same place. From the far curb, shoot the front of the house square on and load it into our roofline measuring tool, which traces the edges by itself. Then tap something of known size for scale. A garage door is ideal, 16 feet for a double and 9 for a single, and a front door or window works at 3 feet.

Pixels become linear feet, peaks and valleys get counted, and both the permanent and the lease price come out of that single measurement. The measuring happens in your browser, and your photo is never uploaded. If detection misses a line, manual mode lets you tap it yourself.

New subdivision fronts in Macomb Township are quick to measure this way, with a street-facing garage door built in as the ruler. The side-entry colonials found in Troy need the front door instead. How to take a photo that measures well, from where to stand to what to do about a tree, is covered in measuring your roofline from a photo.

Better still, do both. When the tape and the tool agree within a few feet, trust the number. When they do not, the gap usually points at a gable.

Confirming on site

A tape total and a photo total are planning numbers. They are good enough to set a budget, compare permanent against a lease, and decide which lines you want lit. They are not what we order from.

Before any channel or C9 run is ordered, we confirm the footage at the house: every run, every peak and the edges you have chosen. Our crews clean roofs and gutters year round, so reading a roofline in person is familiar work. The visit also settles what a tape cannot, like whether the lower eave looks better lit or dark.

To make the estimate go quickly, have the list you wrote at the drip line ready:

• each run with its length, labeled upper eave, lower eave, garage and gable
• the gable widths with your shallow, medium or steep note
• the number of peaks on the front
• whether you want permanent lighting, a seasonal lease, or a price on both

Autumn is the practical window for permanent installs, and the calendar fills in the order requests arrive. When your runs are written down, send your footage through the estimate form. We confirm the request within 24 hours, and your measured feet become a price for your own roofline.

Where this applies

Typical roofline lengths and priced examples for these communities are on their own pages.

• Troy
• Macomb Township

Sources

1. Roof Online: Roof pitch factor table roofonline.com
2. TAMCO: Roof slope factors tamcometalroof.com