Math Behind the Moment™
You can’t fake tension. Or ambiance.
Here’s why overhead lighting needs real structure — and how Pillar Pro™ nails it.
Every string light droops. The question is: how much should it?
Here’s how to calculate the right span, sag, and tension — and why it matters for safety and beauty alike.
To estimate the horizontal tension required to hold a run of string lights over a level span, we use the standard small-sag, uniformly distributed load approximation:
Formula
T ≈ ( w · L² ) / ( 8 · δ )
Where
- T = horizontal tension in the line (pounds, lb)
- w = total weight per unit length of the lights (lb/ft) — include cord, bulbs, clips, etc.
- L = horizontal span between supports (feet, ft)
- δ = mid-span sag (feet, ft)
Important units
If you measure sag in inches, convert to feet first (δ_ft = sag_in / 12).
What this means
For a given span and weight per foot, smaller sag requires higher tension. The relationship is parabolic with span (tension scales with L²), which is why long, flat runs demand much higher forces at the anchors and poles.
Assumptions and scope
- Supports are at equal height; the load is uniform along the span.
- Sag is small relative to span, so the catenary is well approximated by a parabola.
- This is a quick design check, not a stamped engineering analysis. Real-world design should also consider wind, temperature, hardware ratings, and site conditions.
This relationship between span, sag, and tension follows the same curve that defines suspension bridges and power lines—the catenary. It’s the natural shape a line takes under its own weight, balancing gravity and force. Understanding that curve is the foundation of every YARDHAUS overhead system.
The Catenary Curve
Gravity and force at work
Our Lightweight Outdoor Infrastructure™ (LOI) approach uses precision-machined anodized-aluminum poles and simple anchor geometry to create a clean overhead framework. Designed to hold real tension, the LOI system is scalable, easy to install, and built to be permanent—if you want—or easily re-configured as your space evolves. The result: architectural lightness you can feel.
Why the Weight Matters
How can a six-pound strand of string lights create forty pounds of force?
For a 25-foot span with just six pounds of string lights and a six-inch sag, the horizontal tension on the line climbs to nearly 40 pounds — about the same as a five-gallon pail of water hanging ten feet in the air.
That’s a constant, invisible load working against every pole, anchor, and connection point — even before wind or rain add more stress.
We’ve installed a lot of lights over the years, and the Govee lights below are by far the lightest we’ve found.
Even so, we always recommend using a guide wire to reduce wear at each segment and preserve tension integrity over time.
Installing the Framework
The same physics that define the catenary make Pillar Pro installation fast and precise. Pillar Pro's modular design creates a straight, tension-ready line in under 90 minutes — with just a drill.
Pillar Pro - It Holds the Moments
Structure that disappears into design.
- Engineered to hold real tension across spans
- Minimal architectural profile
- Modular mounts for lighting and accessories
Create your slice of paradise
With a single strand of lights overhead, the space starts working. Most decks have lights pushed to the perimeter—great for walking, poor for faces. YARDHAUS uses Pillar Pro to establish an overhead plane so light falls from above—intentional, ambient, and roof-free
New or upgrade
- Upgrade - replace your old setup, or claim your Air Rights on your existing deck
- New - plan Air Rights into your new build.
The basics
- What it does: Pillar Pro creates the overhead plane— that holds lights overhead. Not on the perimeter. Not at waist height.
- Where it lives: Most decks look best with the light line set around 8–10 ft high. A gentle ~6" drape over a ~12' span reads clean and comfortable.
- How it mounts: Railing post-mounted, aluminum poles + a simple anchor point (often on the house).
- What it fits: Works with most wood, composite, and metal railings (metal railing brackets sold separately); compatible with standard string lights or guide wire (guide wire brackets sold separately)
- Lighting options: string lights, bistro/café lights, pendant lights. Use a guide wire for longer runs, straighter lines, or pendants.
Design help
- Not sure about height, span, or rail details? We’ll map some suggested layouts for you—free.
- What to send: a few photos of your deck, railing, and stairs, plus approximate length × width.
- What you’ll get: a fit confirmation, suggested product list, and a simple layout sketch
Mini FAQ
- Does this add a roof? No—Pillar Pro adds one overhead slice (the Light Line); your Air Rights stay open.
- Will it work on my deck? In most cases, yes. If you’re unsure, email a photo to service@yardhaus.co and we’ll confirm fit.
- Guide wire compatible? Yes.
- Install time? Under two hours for most decks.
- Returns? 30-day Better-Lit Deck guarantee.
Free Shipping | Award-Winning Design | Lifetime Warranty
The Light Hanging Kit
It holds the lights, so you can share the moment.
Patented compression anchors and anodized aluminum deliver a solid, contemporary overhead lighting installation system that performs as beautifully as it looks — an award winning way to put lights where they should be.
Claim Your Air Rights™ Today.