Is there an alternative to NFPA 13D fire sprinklers for modular or prefab homes?

Yes. Automist is a UL Listed water mist system that is increasingly being used as an alternative to traditional NFPA 13D sprinkler systems in modular and prefabricated construction.

Conventional sprinkler systems can create challenges for offsite builds. Rigid pipe networks typically require inspectors to view every joint on-site, which often means ceilings and walls must remain open until final inspection. This shifts finishing work from the factory to the job site, undermining the speed, cost control, and quality advantages that modular construction is designed to deliver.

Automist supports a more factory-aligned approach. Many Authorities Having Jurisdiction (AHJs) accept either:

• Factory-installed systems with pressure testing and verification on-site, or
• Pre-installed conduit routes, allowing flexible hose to be pulled through and connected on-site

Because Automist uses flexible hose and wall-mounted spray heads instead of rigid ceiling pipework, connections are accessible and verifiable without opening finished surfaces. This allows more work to be completed in the factory, improving build efficiency, consistency, and repeatability.

Water supply is another key constraint for modular and offsite housing. Automist operates at a much lower flow rate and connects directly to the standard domestic water supply, meaning in most cases:

• No tapping or meter upgrade is required
• No storage tank is needed

The system is also compact. The pump unit (9″ × 7″ × 14″) fits under a sink or within cabinetry, aligning with the space constraints and repeatable design processes of modular construction.

As California and other states look to scale factory-built housing to address housing shortages, reducing on-site complexity, inspection friction, and infrastructure requirements is becoming increasingly important. Systems like Automist support this shift by enabling more of the build to be completed in the factory without compromising fire protection. As with any fire protection system, acceptance depends on your local AHJ, so it is important to confirm the preferred approach early in the design process.

Disclaimer: This information is not intended to be a comprehensive guide to all of the aspects of the building/fire code but rather a useful source of background information. Whilst every care has been taken to ensure that the contents of this post are correct at the time of publication, it should never be used as any form of substitution for the full NFPA® codes, standards, recommended practices, and guides. It should be noted that there may be specific additional requirements dependent upon the Authority Having Jurisidiction (AHJ).