How many C9 bulbs do you need for a 6,000 sq ft house?
Estimating bulb count for a 6,000 square foot house before the site walk is a common ask from installers pricing jobs remotely. The answer depends on roof style, run count, and whether the property owner wants secondary architectural lighting — but there are usable ranges.
Roofline linear feet for a 6,000 sq ft house
A 6,000 sq ft single-story home with a simple hip roof runs about 300-400 linear feet of primary roofline. A two-story 6,000 sq ft home with the same footprint has roughly the same primary roofline because the extra square footage is stacked, not spread.
A 6,000 sq ft home with multiple gables, dormers, wings, or a complex roof (common in luxury residential) runs 500-800 linear feet of lit-able edge. On the upper end of that range the property may cross into commercial install classification for permitting purposes.
Bulb count by spacing
At 12-inch spacing (standard install): 400 feet × 12 / 12 = 400 bulbs raw. Add 8 percent overage = 432 bulbs. Round to the nearest 25-count pack = 450 bulbs.
At 6-inch spacing (dense luxury install): 400 feet × 12 / 6 = 800 bulbs raw. Add 8 percent overage = 864 bulbs. Round to the nearest 25-count pack = 875 bulbs.
At 15-inch spacing (wider install): 400 feet × 12 / 15 = 320 bulbs raw. Add 8 percent overage = 346 bulbs. Round to the nearest 25-count pack = 350 bulbs.
The Kit Builder tool at /kit-builder runs this math live for any footage and spacing combination.
Secondary architectural lighting
Homeowners on properties this size often request secondary lighting — column wraps, entry arch lighting, deck railings, dormer edges, landscape lighting. On a fully-lit luxury install, secondary lighting can add 200-500 additional feet on top of the primary roofline.
Add secondary lighting into the estimate as a separate line rather than folding it into the roofline count. That way the property owner can see the incremental cost and can trim scope if the total exceeds budget.
Spool selection for a 6,000 sq ft house
For a 400-foot roofline with 12-inch spacing, a single 500-ft SPT-1 socket spool is the natural pick — 100 feet of spare spool at the end of the run gives room for terminations and drops without splicing.
For a 700-foot complex roofline with 6-inch spacing, one 1,000-ft SPT-1 spool is the clean pick. Alternatively a 500-ft plus a 250-ft spool gives more flexibility on branching but adds a splice terminal.
For a commercial-adjacent property with SPT-2 spec, the same footage math applies but the spool line item is SPT-2 rather than SPT-1.