NEW SMOKE VENTING GUIDELINES

Written by: Andrew J. Johnson

The rules of the game have been changing for those building new warehouse space or extensively remodeling an existing facility because of the widespread adoption of the International Building Code (IBC).

Developed by the International Code Council, the IBC was introduced in 2000 and updated in 2003. Since then it has gained broad acceptance across the United States, with many state legislatures adopting it on a statewide basis. In Illinois, building codes are the province of local government, so adoption of IBC has been more gradual. Now, however, it is reaching critical mass, with about two-thirds of Illinois municipalities adopting IBC.

One aspect of the IBC that can catch warehouse owners by surprise is the requirement for smoke venting in storage facilities with ceilings 12 feet high or greater. Provisions for smoke venting have a long history and are designed to make it easier and safer for firefighters to operate inside a burning building. However, the advent of mandated sprinkler systems in the 1980s made smoke venting less critical, and many codes dropped the requirement for buildings with sprinklers.

The return of smoke venting requirements is based on the experience gained in the intervening years, primarily the realization that sprinkler systems don’t always do the job. When they don’t, firefighters must go in, and smoke venting often helps them.

The new IBC smoke venting requirements apply to most new warehouses, but not all and they also can apply to older buildings if they are substantially remodeled or expanded. In some instances, the presence of an ESFR sprinkler system still makes venting unnecessary. However, warehouses that stack or rack any type of combustible materials will now need venting of some type.

There are two basic types of venting systems. • Passive systems employ hatches or skylights that permit smoke to escape otherwise unaided. • Active systems typically employ exhaust fans to move smoke out of a building interior.

Either type of system then can be set up to function automatically or in response to a manual command. Automatic systems include skylights that melt when interior temperatures reach a certain level, hatches are opened when a link made of a fusible alloy melts or fans that begin operating in response to an alarm system or sprinkler activation.

Manual systems give control to the firefighters, allowing them to decide when or if to activate the venting. The relatively new IBC 2003 puts additional emphasis on manual systems, and fire departments in many communities are working aggressively to put requirements for manual venting into existing codes.

The need to provide venting will add to the cost of building a new facility or remodeling an older one.

We recently completed the installation of a passive venting system that utilizes melt away skylights as part of a major warehouse expansion in Addison, Ill. In that instance, the added cost was approximately $54,000 for a 100,000-square-foot structure.

Active systems are even more costly and usually would not be installed in retrofit situation. However, where a new warehouse requires extensive exhaust system for its normal operations, using that same system for smoke venting actually can save money.

When that is done, however, it is necessary to make sure the system is wired so that it remains operable if the main disconnect for the building is shut down and that the controls for the venting system are easily accessible to firefighters and protected by fire-barriers with a resistance rating of not less than one hour.

Active systems can remove smoke more quickly and can require fewer venting outlets. For venting systems, the IBC requires most warehouses to provide one square foot of venting area for each 100 square feet of floor space within the building. For example, in the 100,000-square-foot Addison warehouse project mentioned earlier, our roofing contractor installed 18 skylights, each measuring six by eight feet to comply with the IBC. However, the vent to floor space ratio can increase to one to 20 in buildings that hold especially hazardous materials.

IBC regulation also requires the vents themselves must be at least 16 square feet each, with no dimension less than four feet.

How these IBC smoke venting regulations apply to warehouse renovation can be another source of confusion. In most instances, buildings being renovated must meet current code requirements if the project results in a 50 percent or greater change in the building. That leaves some room for uncertainty, and as in all such situations, the best solution is to develop a good working relationship with the local municipality and its building code enforcement staff.