For years, data center containment relied on "fallout panels"— horizontal roof panels that helped to seal roof systems in cold aisle containment, vital for cooling efficiency. In the case of fire, these panels were designed to drop from the horizontal roof system, allowing suppression systems or sprinklers to operate.

The design worked as intended but also created an unintended consequence in some jurisdictions. Since the panels drop out of the horizontal roof system and fall to the floor, some AHJs (Authorities Having Jurisdiction) have flagged this as a life-safety issue rather than a minor compliance footnote, banning fallout panels in all new builds and retrofits.

This left data centers in these jurisdictions with no compliant means of sealing containment roofs. For years, facilities were left with two options: leave the gap or install sprinklers in every aisle. Most operators took the simpler route, leaving the aisle never truly sealed.

What was required was an alternative material to solve the problem in these locations. Something that wouldn't fall, wouldn't burn, and would disappear cleanly when hit with sprinkler water. Surprisingly, the fix came from outside the industry, found in a material already used in food production and nuclear facilities. It was EPA-safe, non-combustible, and able to dissolve almost instantly on water contact.

This article details DAB panels' origin story to help us understand why this material exists and why it's now effectively the de facto standard for compliant containment in markets where fire code enforcement is strictest.

Where Containment Meets Compliance: How a Life-Safety Ban Reshaped Data Center Containment

Containment has long been considered the standard for cooling efficiency. Sealing the aisle and properly regulating airflow are relatively straightforward measures based on well-established principles of physics that consistently deliver proven energy savings and lower cooling costs. But full containment only works if the aisle is completely sealed. So why has the roof never been fully sealed in all data center locations?

For many years, the ceiling panel has been closed with what the industry refers to as fallout panels. As per fire regulations, these lightweight roof panels were designed and engineered to do exactly what their name suggests; in a fire event, they dropped out of the horizontal roof containment grid, clearing the way for sprinklers to reach the aisle below. It was a clever piece of dual-purpose design: seal the space for cooling, then drop out of the way for safety.

The trouble exists in some jurisdictions with "dropping out of the way".  

When the Fix Became the Problem

Fallout panels worked in exactly the way they were built. However, in a fire event, as the panels were released from the horizontal containment ceiling grid, they landed, and in a working aisle, they drop into the very space that first responders and evacuating personnel needed to move through. Unfortunately, what had been designed as a life-safety feature was, in practice, generating debris in the exact corridor people needed clear.

While not an issue everywhere, AHJs didn't just treat the situation as a minor code infringement. It was flagged as a safety issue, and the response was decisive. Fallout panels were banned outright across an increasing number of jurisdictions.

That left the data center industry with a real design quandary. Containment still needed a sealed roof to deliver its cooling efficiency. Fire code still needed suppression systems to reach the aisle unobstructed, and the one option that reconciled those two demands was no longer allowed.

Two Poor Options

With fallout panels no longer a choice in certain jurisdictions, this left new and legacy data centers with no compliant means of sealing containment roofs. Data center operators were left picking between two compromises:

1. Leave the roof gap. Skip a sealed roof system of the cold aisle entirely, accepting the air mixing between the hot and cold aisles and absorbing the efficiency loss. This was, and still is, the path most operators in these locations defaulted to, simply because it required no new engineering. It also meant a large share of "contained" data halls were never truly sealed.
2. Sprinkler every aisle. Rather than relying on panels to clear the way for fire suppression, install pipe sprinkler heads inside every contained aisle. While this option solved the code problem, it adds cost, complexity, and a maintenance burden most facilities aren't designed or prepared for.

Neither option solves the underlying problem. So how do you seal a contained cold aisle for cooling purposes while guaranteeing, with certainty, that it will not become an obstruction or a hazard the moment fire suppression is activated?

Looking Outside the Industry

The eventual answer didn't come from a cooling engineer or a fire protection specialist. It came from re-examining the material itself.

The specification was narrow and demanding. The panel required was one that would not fall as rigid debris, would not burn or add fuel to the fire, and would immediately remove itself from the aisle the instant it contacted sprinkler water. It needed to do this automatically without manual removal or contribute to post-incident cleanup.

It was discovered that this combination of properties did already exist, just not near any data center. A water-soluble, non-combustible sheet material had been used for years in food production environments, and in nuclear facility applications. This solution is suitable for all contexts where a barrier needs to hold its shape under normal conditions and then disappear instantly and safely on contact with water. By virtue of its existing applications, this material has already been certified EPA-safe, is already non-combustible, and already proven to dissolve almost immediately on water contact.

Applied to containment, this became what the industry now refers to as a Dissolvable Air Banner (DAB) panel. A containment roof panel that seals the aisle for cooling purposes exactly as a fallout panel but one that responds to a fire event by dissolving rather than falling. No debris. No obstruction. No secondary hazard for firefighters or evacuating staff. The suppression system can reach the aisle within seconds of activation, and the panel itself ceases to exist as a physical object in the space.

Why It's the Default

In markets with the strictest fire code enforcement – jurisdictions where AHJs scrutinize containment design line by line – DAB panel systems have evolved from a novel alternative to a de facto specification. As the last line of defense against exactly the issue fallout panels created, AHJs are not typically early adopters of unproven materials. Their acceptance of DAB panels as a compliant solution therefore says more about the material's reliability than any vendor claim could.

Lessons Learned

The lesson embedded in the fallout panel's ban in certain locations is a useful one for the sector generally: a design that satisfies and is acceptable in one jurisdiction doesn’t necessarily get approval in another one.

In this case, the fix wasn't a smarter version of the old panel. It was recognizing that the old panel was solving the wrong problem and that elsewhere the right material had been solving it all along.

For operators still considering the dilemma of gapped roofs versus aisle sprinkler retrofits, the DAB panel option is definitely worth a second look. It’s not an emerging trend but a solved problem borrowed from industries that found the solution first.