Roofing underlayment performance is highly dependent on storage conditions.
Throughout the year, we received some complaints related to:
- Surface printing or ghosting
- Telescoping rolls
- Wrinkling
- Underlayment that is difficult to unroll
What made these complaints unusual:
- The batches traced back clean
- Retained samples from the same production runs performed perfectly
- No formulation or process issues were found
We later found out the root cause was storage conditions.
The Two Most Common Storage Issues
Across all cases, the same factors appeared:
- Underlayment stored horizontally
- Prolonged exposure to direct sunlight or heat
Both create predictable deformation in asphalt-based roofing underlayments.
Why Horizontal Storage Causes Underlayment Deformation
When rolls are stored horizontally:
- The full weight of the roll applies constant pressure to one side
- Heat softens the asphalt over time
- Internal layers shift unevenly around the core
This leads to:
- Telescoping
- Surface prints
- Internal stress memory
- Rolls that resist laying flat during installation
Why Direct Sunlight Makes the Problem Worse
Even high-temperature rated underlayments are not designed for long-term UV and heat exposure during storage.
When rolls are stored outdoors or in direct sunlight:
- Surface temperatures rise far above ambient air temperature
- Asphalt softens while under compression
- Release films and surface textures imprint into the membrane
This can result in:
- Visible surface markings
- Wrinkling during unrolling
- Difficulty in peeling release film
- Reduced handling ease for contractors
Why Retained Samples Perform Normally
Quality control samples are stored:
- Vertically
- Indoors
- In temperature-controlled conditions
- Away from UV exposure
The same batch with different storage behavior and different outcome.
Best Practices for Roofing Underlayment Storage
For customers carrying roofing underlayments:
- Store rolls vertically, never horizontally
- Keep pallets out of direct sunlight
- Avoid long-term outdoor storage, especially in warm climates
- Do not stack pallets in ways that introduce side load or compression
- As much as possible, follow first-in, first-out inventory rotation
Good product plus proper storage results in fewer callbacks and fewer headaches.
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