Appeal 34963

Table 601 – Floor construction and associated secondary structural members for Type V-A

1-hour fire-resistance rating

It is requested to provide non-fire-resistance-rated floor construction at the proposed deck replacement.

CLASSIFICATION: Classify the deck as a “similar projection” per §705.2.3.1.

SPRINKLERS PROVIDED: Extend sprinkler coverage to the deck through a dry automatic sprinkler system.

NON-RATED FLOOR CONSTRUCTION: Provide non-fire-resistance-rated floor construction at the deck as allowed per §705.2.3.1 Exception 3.

1-HOUR SUPPORTING CONSTRUCTION: Provide all supporting construction with a 1-hour fire-resistance rating. Wood beams and joists will be calculated to meet char depth requirements as allowed per AWS 2018 National Design Specifications (NDS) for Wood Construction and outlined in Technical Report 10 (TR10). Steel posts will be protected with 1-hour spray-applied fireproofing. See detail on A0.70.

LIMITED LENGTH: Limit the aggregate length of the deck to not more than 25 percent of the building’s perimeter on the level it is associated with.

LIMITED FLOOR AREA: Limit the total area per floor to that of Type V-B (including the increase for sprinklers and frontage).

INDEPENDENT EGRESS: Provide all egress for the building independent of the deck; provide all egress for the deck independent of the building.

TRAVEL DISTANCE: The maximum exit access travel distance for the deck area is less than the 75 ft allowed for common path of travel.

FIRE-RESISTANCE RATING FOR TYPE OF CONSTRUCTION: The proposed deck is covered and considered part of the building area, thus requiring compliance with the fire-resistance rating of building elements per Table 601. While most fire-resistance ratings are achievable, the floor construction is not due to both the plank dimensions and the gaps between the planks to allow for drainage.

FIRE-RESISTANCE RATING AS A SIMILAR PROJECTION: Per §705.2.3.1, balconies and similar projections are allowed to be constructed of heavy timber construction in accordance with §2304.11. However, compliance with this section cannot be fully achieved due to the dimensions of the planks and the lack of sheathing in the floor construction.

SPRINKLER PROTECTION TO ALLOW NON-RATED FLOOR CONSTRUTION: Therefore, it is proposed to apply §705.2.3.1 Exception 3 which allows a “similar projection” to be of Type V-B construction where sprinkler protection is extended to these areas. While the definition of “balconies and similar projections” is not defined, the 2021 IBC Commentary §705.2.3.1 lists “balconies, porches, decks, …” together when describing the requirements for this section; thus, it is asserted that decks fall under “similar projections”. The difference for this deck as opposed to most “balconies and similar projections” is that it is a self-supporting, independent structure that is not supported by the building. However, the contribution to fire loading on the building is the same, whether independent or not, and the proposed sprinkler protection will reduce this risk substantially.

INDEPENDENT EGRESS AND TRAVEL DISTANCE: As stated in the proposed design, the egress for the building and deck areas are independent; therefore, the occupants of the building are not relying on the deck for egress. As well, the total travel distance for deck occupants is less than the 75 ft allowed for common path of travel for Group A occupants; this includes the distance on-grade to the edge of the deck overhang. So, while the floor construction is not protected with a 1-hour fire-resistance rating, the path of egress is very short, as is the duration during which this floor needs to serve occupants egressing. Additionally, a fire/smoke event originating from or near the deck space would be easily detectable, both visually and through smell, allowing occupants plenty of time to egress. This could likely occur even before activation of the sprinkler system. See G0.31 for clarification.

BUILDING AREA RELATIVE TO TYPE OF CONSTRUCTION: The largest floor is 18,725 sf. While the application of a frontage factor of .75 is all that is required to meet building area for Type V-A construction (allowing up to 20,125 sf per floor), Type V-B construction could be met for each floor in terms of area when considering both sprinklers and frontage (allowing up to 19,500 sf per floor when applying the minimum frontage factor of .25, which the building exceedingly meets); meaning, if the building was considered as two stories instead of three, with the lower level classifying as a basement (which it appears to meet the requirements for) adjacent to a double-height space that connects to the first story, the building would comply with Type V-B construction. Unfortunately, it is currently permitted as three stories and would require some interpretation and discussion to change that classification. Classification as Type V-B would, of course, allow the deck to be constructed of non-rated construction. Therefore, it is proposed to limit the area per floor to that allowed for Type V-B to support classification as a “similar projection”. See attached Cascade Crest As-Built Drawings of Main Building for clarification.

CONCLUSION: It is requested to allow the deck floor construction to be classified as a “similar projection” per §705.2.3.1, thus meeting compliance with §705.2.3.1 Exception 3 since the area is provided with a dry sprinkler system. This allows the floor construction to be provided without a fire-resistance rating.

ATTACHMENTS:
Appeal Attachment #1 (G0.20, G0.30, G0.31, A0.70, A0.80, A1.00, A1.10, A1.11, A1.60, A1.61, A2.00, A2.50, A2.51, A3.00)
Appeal Attachment #2 (Cascade Crest As-Built Drawings of Main Building – A3.3 and A3.4)