FAQ: What do I use to outline my roof?
Outlining rooflines with Christmas lights is one of the most classic — and most satisfying — ways to decorate a home. While the finished look feels simple, a clean installation relies on choosing the right materials from the start.
This guide walks through the core components used for traditional C7 and C9 roofline installations, along with practical tips to help you plan, build, and install with confidence.
1. Christmas Light Cord
Traditional C7 and C9 Christmas light cords are constructed using stranded 18 AWG lamp cord and are rated for up to 10 amps. Sockets are evenly spaced along the line and are designed to accept either C7 or C9 bulbs, depending on the socket size.
The terms C7 and C9 refer to the size of the bulb base — not the cord itself. Because the bases are different sizes, C7 bulbs require C7 sockets, and C9 bulbs require C9 sockets.
All available C7 and C9 cords can be found in our Christmas light cord collection.
Learn more: Are C7 and C9 bulbs the same? · Can you mix C7 and C9 bulbs in the same cord?
2. Christmas Bulbs
Choosing bulbs is where style really comes into play. Once you’ve selected the correct socket size, the remaining decisions are about look, color, and technology.
- Bulb size: C7, C9, or round bulbs like G30, G40, or G50
- Technology: Glass incandescent or LED
- Finish: Smooth, faceted, opaque, or twinkle
- Color: Classic warm white, multicolor, or bold single colors
Browse available options on our Christmas bulb collection page.
3. Christmas Light Clips
Clips are what turn loose cords into a clean, professional-looking roofline. The right clip depends on how your roof is built and where you plan to mount the lights.
Many clips slide under shingles, while others flip to mount directly onto gutters. For a crisp outline, plan on using one clip per socket.
The clip shown above is the All-in-One Clip , a long-time customer favorite because it works on shingles, gutters, and rails.
View all available options in our Christmas clip collection .
4. Gilbert (Vampire) Plugs
One of the advantages of 18 AWG Christmas light cord is that it can be cut to length. Once cut, the cord needs a plug — and the easiest solution is a Gilbert (vampire) style plug.
Male plugs are used at the start of a line, while female plugs can terminate a run or be paired with bulk wire to create custom jumpers between roof peaks or windows.
Bulk wire is available here.
Installation & Electrical Tips
- Never exceed 250 feet of 18 AWG cord (including jumpers) on a single circuit.
- Add up bulb wattage per breaker and stay under 80% of maximum load.
- Build and test cords before installing them on the roof.
- Install clips on sockets before mounting whenever possible.
- Use outdoor-rated surge protectors to protect your investment.
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