As a result of rising real estate costs and a shortage of space, "high-piled combustible storage" buildings such as warehouses, manufacturing facilities, and retail buildings are getting taller to take up the least amount of square footage possible. However, taller spaces need increased fire protection, and new storage methods present engineers with challenges they may not have previously encountered.

Definitions and Permits

High-piled combustible storage is defined by most fire codes as storage of closely packed piles of combustible materials on pallets, in racks, or on shelves where the storage top is greater than 12 ft in height. When high-hazard commodities are involved (e.g., Group A plastics, rubber tires, flammable liquids, and idle pallets), minimum height drops to 6 ft.

Most codes require that an operational permit is obtained when more than 500 sq ft of high-piled storage is present in a building. These permits are most often regulated by fire departments and are not transferable to new tenants or building owners. The reason for the prerequisite is that the required protection features are dependent on the proposed storage commodity, height, and method of storage, thus ensuring that each individual case be reviewed for compliance. Quite often, the existing protection (if present at all) is inadequate.

Potential clients frequently call in a panic, having purchased a building that was previously used as a warehouse or storage facility only to find out that they need to obtain a high-piled storage permit. Even when a facility is new and the project team is aware of the high-piled storage issue, those tasked with obtaining permits often are not fully aware of the requirements (including local ordinances) associated with this hazard or do not have a full understanding of the appropriate system design.

Required Protection

The required protection for high-piled storage areas falls into six main categorizes: automatic fire-extinguishing systems; fire detection system; building access; curtain boards, smoke and heat removal; small hose valves and stations; and storage limitations.

Automatic fire-extinguishing systems are typically provided using an automatic sprinkler system. Common installations include ESFR sprinklers, which are specifically designed for the protection of storage, or standard ceiling systems with in-rack sprinkler systems. The fire detection systems requirement usually includes smoke or heat detection, with a good requirement being beam-type smoke detection systems.

Building access involves providing the fire department with exterior access doors and an access road around the building. When curtain boards, and smoke and heat removal is required, automatic smoke and heat vents (operable skylights) are provided and the warehouse space is divided by curtain boards that extend 6 ft down from the ceiling into areas of 10,000 sq ft or less.

Small hose valves and stations, which are 1.25-in. hose valve connections and 100 ft of hose evenly spaced throughout the storage area, are typically required for manual fire fighting and mop-up operations by the fire department. Storage limitations represent a set of restrictions placed on aisle widths, size of storage piles, and flue spaces.

Sprinkler System Challenges

The most difficult protection issue in terms of design expertise is the sprinkler system. It tends to be the most cost intensive but also provides the most protection for the money. There have been numerous advances in recent years, with sprinkler companies continuing to produce a wider selection of products with different flow characteristics.

Improvements include low-pressure, quick-response, and extended coverage sprinklers. For protection, the most significant advances have been the ESFR, ESFR K25, and K-17 sprinklers that allow users to provide required protection at lower pressures or eliminate the requirement for in-rack sprinklers. Difficulties in providing adequate sprinkler systems do not appear to stem from improper design or installation but with changes in what is being protected. Tenants also change, as does the storage.

New Codes

So what does the future hold given the development of the new building codes (ICC, NFPA)? As far as high-piled combustible storage is concerned, not much relief is provided. The most significant changes deal with the installation of curtain boards. The elimination of curtain boards for buildings/areas protected with automatic sprinkler systems is being allowed, but the new codes still refer to the smoke and heat venting requirements of the "building code," which in turn requires some curtain boards.

In summary, anyone involved with high-piled storage, whether it is a new project or an existing warehouse, should be aware of what it involves. Too many times, this issue is not dealt with properly or early enough and it spells trouble for any project. ES