Old Skylight Panels Kill Daylighting Performance (And No One Notices Until It’s Too Late)
Walk into a 20–150k sq ft metal building with 15–20-year-old LTP skylights and you’ll hear it:
“We’ve got skylights… but it’s still dark in here.”
The problem isn’t that the building lacks daylighting.
It’s that aged Light Transmitting Panels (LTPs) silently lose performance over time.
In a recent warehouse project, we measured light levels at floor height in an empty building before and after replacing old LTP panels with new RS36 skylights.
- Before (aged LTPs): ~10 lux
- After (new RS36): ~80 lux
That’s an 8× increase in delivered daylight.
Same building. Same roof openings. Same day.
The only change was the skylight system.
What Happens to Old LTP Skylights?
Traditional LTP panels degrade gradually:
- UV exposure causes yellowing
- Resin oxidation reduces visible light transmission
- Surface crazing traps dirt
- Microfractures scatter light instead of delivering it
From the roof, they may still “glow.”
But at the floor, where people actually work, daylight performance drops dramatically.
And because the decline is gradual, it rarely triggers a clear “failure” moment. It just becomes normal for the building to feel dim.
How Aging LTP Skylights Undermine Daylighting Performance for General Contractors
Reduce Callbacks. Improve Perceived Quality.
When a renovated building still feels dark, owners don’t blame the sun.
They question:
- The lighting plan
- The renovation scope
- The contractor
Replacing aged LTP panels is a low-disruption way to dramatically improve how a space feels, without changing structure, layout, or electrical systems.
An 8× increase in floor-level daylight:
- Makes the building feel newer
- Improves tenant perception
- Enhances walkthrough impressions
- Elevates overall project quality
Instead of just “fixing the roof,” you’re restoring building performance.
That’s a measurable upgrade you can stand behind.
How Aging LTP Skylights Undermine Daylighting Performance for Roofing Subcontractors
Upgrade Instead of Patch.
Most aged LTP panels are:
- Brittle
- Yellowed
- Cracked or crazed
- Nearing structural failure
Aged LTP panels are not just dim, they’re often brittle and unsafe to work around.
The traditional approach is patching or replacing a few damaged sections.
But that only solves leaks.
It doesn’t solve daylight loss.
When you replace degraded panels with a high-performance skylight system, you’re offering:
- Structural renewal
- Daylight restoration
- Improved interior brightness
- A visible, immediate upgrade
Instead of a maintenance repair, it becomes a performance improvement.
That changes the conversation from:
“We fixed the problem.”
To:
“We improved the building.”
And that’s a stronger, higher-value position.
The Bigger Issue: Silent Performance Failure
Old LTP skylights don’t fail dramatically.
They fail gradually.
By the time a building “feels dark,” transmission may have dropped significantly from original performance levels.
Electric lighting often gets blamed.
But in many cases, the skylights are no longer doing their job.
Measured at floor level in an empty warehouse, replacing aged LTP skylights increased usable daylight from ~10 lux to ~80 lux, an 8× improvement.
Same roof openings.
Very different performance.
If Your Project Has 15+ Year-Old LTP Panels…
Replacing degraded panels isn’t just a roof repair; it’s a daylight restoration strategy that improves interior brightness, restores intended performance, and enhances how the space feels from the ground up. R&S skylights are engineered specifically for commercial metal roof systems, delivering consistent light transmission, structural reliability, and panel-specific fit. The result isn’t just a new skylight, it’s measurable daylight performance you can see at floor level.
If the building feels dark, the skylights may already have failed, quietly.
