1. Aggregate area of clusters of portable school classrooms does not exceed 5,000 square feet (1465 m²); and
2. Clusters of portable school classrooms shall be separated as required in Chapter 5.

2. Is there a specific separation distance which would allow the portables not be classed as a cluster? 

3. Is it the intent of this exception that even if the buildings are separated as required in UBC Chapter 5, if the aggregate area exceeds 5,000 square feet they are still required to be provided with a fire-extinguishing system? 

4. Is the exception cumulative?

2. A spacing of 20 feet or greater would be outside the limits of Table 5-A at which separation distance the portables would not be classed as a cluster. (See also SBCC Interpretation No. 93-10.) 

3. The intent of this exception is to exempt portable school classrooms from the automatic fire-extinguishing system requirement. It is clear from RCW 19.27.113 that this was the intent of the legislature. The 5,000 square foot aggregate area limit of a cluster is imposed to provide a level of safety. 

If the 5,000 square foot aggregate area limit is exceeded, the exception would no longer apply and the cluster of portables in question would be subject to the automatic fire-extinguishing system requirement. 

4. This exception would allow any number of complying clusters of portable school classrooms on one site where the clusters are separated from one another as required in Chapter 5. The separation could be by spacing between clusters in accordance with Answer 2 above or since a cluster is considered to be "one building" per Section 503.3, an area separation wall complying with Section 504.6 could be used to separate one cluster (i.e. "building") from another.