When installing a fence, one of the most important steps to ensure a straight, professional-looking result is setting a string line. Whether you’re working on a Greenwood Fence modular system or any horizontal slat design, a well-placed string line will keep your posts and panels aligned from start to finish.
Why a String Line Matters
A string line acts as your visual guide during installation, ensuring that every post and panel lines up perfectly. Without it, your fence could end up with dips, waves, or misaligned sections—something that’s easy to avoid with proper prep.
Step-by-Step: Setting Your String Line
- Mark Your Post Locations Begin by marking the exact locations where each fence post will go. Use spray paint, stakes, or flags for clear visibility.
- Install Corner or End Posts First Set your first corner or end post securely. These posts will act as the anchor points for your string line, so ensure they’re perfectly plumb and level.
- Attach the String Line Tie your mason’s line or durable string to the first post at the exact height where the top of your bottom rail should sit. Pull the string tight and secure it to the opposite corner or end post.
- Check for Level Use a level to make sure your string is perfectly straight. Even small deviations can affect your final fence line, so take your time here.
- Align Posts to the String As you set each post, bring it just to the edge of the string without pushing the string out of line. This ensures all posts stay aligned while keeping your fence straight and professional-looking.
- Recheck Often During installation, periodically recheck your string line tension and height. Weather, foot traffic, or accidental bumps can cause the line to shift.
Pro Tips for the Best Results
- Use bright-colored mason’s line for better visibility.
- For long runs, consider resetting your string to eliminate sag.
- Always confirm post spacing before digging to avoid surprises.

The Greenwood Fence Advantage
When you combine a well-set string line with Greenwood Fence’s modular fencing system, you get a fast, precise installation every time. Our prefabricated components, adjustable gates, and tested durability make it easy for both contractors and DIYers to achieve flawless results that last for decades.