Do You Use Student Housing RFIs? Should You?

Originally published by the following source: SBC MagazineOctober 7, 2019
by Sean Shields and Kirk Grundahl, P.E., with contributions from SBCA Professional Engineering Staff

   

When large groups of students gather together and dance, it can create loading conditions neither intended nor anticipated by the building designer. Unfortunately, structural failures in these instances can receive national media attention. A recent floor collapse at Clemson University is a prime example with other examples found at the bottom of this article. In a third party report published by EFI Global, the lead engineer found that the collapse was likely caused by the "rhythmic jumping up and down of the closely spaced crowd attending the party, overloading the trusses."

Given the rise in buildings being built for student housing, and the increased potential for rhythmic dancing loading conditions, it is wise to clearly define the approved floor loads. An example request for information (RFI) and confirmation of design load conditions follows:

Loads to be Modified Per Plan Condition Applied To
____psf 40 psf Live Load Living Top Chord
____psf 40 psf Live Load Corridor Top Chord
____psf 100 psf Live Load Public & Lobbies Top Chord
____psf 27 psf Dead Load All Interior Top Chord
____psf 50 psf Dead Load Exterior Terrace Top Chord
____psf 0 psf Live Load All Conditions Bottom Chord
____psf 3 psf Dead Load 1 hr Ceilings Bottom Chord
____psf 6 psf Dead Load 2 hr Ceilings Bottom Chord

Having this RFI reviewed and confirmed ensures that the owner, building designer, general contractor, component manufacturer and framer know that the occupancy conditions surrounding student housing have been considered and the assumed design loads, as defined in the original plans and specs, are either modified or accepted as defined in the original plans and specs.

310.3 Residential Group R-2

Residential Group R-2 occupancies containing sleeping units or more than two dwelling units where the occupants are primarily permanent in nature, including:

Considerations for Defining Student Housing Design Loads

Floor framing elements, whether they are trusses or I-joists, are designed and installed to resist loads defined by the International Residential Code (IRC) and International Building Code (IBC). Additionally, the IRC and IBC both define the maximum number of people expected to be in a given area. The assumptions that the building designer makes about occupancy are defined and listed on their plans and specifications through occupancy designations. For student dorms, the building is typically defined as Residential Group R-2.

The 2018 IBC defines the maximum occupant load for this space in Section 1006 Egress from Spaces:

TABLE 1006.2.1

SPACES WITH ONE EXIT OR EXIT ACCESS DOORWAY

OCCUPANCY

MAXIMUM
OCCUPANT
LOAD OF
SPACE

MAXIMUM PATH OF EGRESS TRAVEL DISTANCE (feet)
Without Sprinkler System (feet) With Sprinkler System (feet)
Occupant Load
OL ≤ 30 OL > 30
R-2 20 NP NP 125a

Source: UpCodes

TABLE 1004.5

MAXIMUM FLOOR AREA ALLOWANCES PER OCCUPANT

FUNCTION OF SPACE OCCUPANT LOAD FACTORa
Dormitories 50 gross
Residential 200 gross

Source: UpCodes

As can be seen in Table 1006.2.1, there is a specific expected limit of 20 students in a room, the door cannot be more than 125 feet from an exit, and the building is required to have sprinklers. It should be noted that all of these requirements are related to ensuring proper egress for all occupants should a fire break out, and has nothing to do with applied loads.

Additionally, Table 1004.5 defines the number of occupants based on a rate of one occupant per unit of area. As an example, it is anticipated that the maximum number of people would be:

  1. 20 total students in a. dorm or apartment that is 1000 sq. ft. in size.
  2. 5 total people in a home that is 1000 sq. ft. in size.

Likely, this is much less than anticipated by most everyone.

1004.9 Posting of occupant load

Every room or space that is an assembly occupancy shall have the occupant load of the room or space posted in a conspicuous place, near the main exit or exit access doorway from the room or space, for the intended configurations. Posted signs shall be of an approved legible permanent design and shall be maintained by the owner or the owner’s authorized agent.

The IBC also recommends posting occupancy limits in every “assembly” room. Hotel rooms, theaters, and restaurants are common examples. While this does not apply to R-2 occupancies, given the number of high occupant loads that have occurred in the last few years in student housing, building designers should consider adding occupancy limit signage to their specifications and encourage owners to clearly define occupancy limits through building occupant rental contracts and publicly posted reminder signage.

Expected Loading Conditions

The building designer should also seriously consider encouraging owners to revise their assumed live load conditions for student housing. It is reasonable to assume that, unless there are clear restrictions, students will congregate in dormitory rooms or apartments. This is increasingly the case given recent national media coverage of dance parties.

From an assumed design load point of view, the IBC Table 1607.1 provides counsel where “assembly” occupancies are expected.

TABLE 1607.1

MINIMUM UNIFORMLY DISTRIBUTED LIVE LOADS, L0, AND MINIMUM CONCENTRATED LIVE LOADSg

OCCUPANCY OR USE UNIFORM
(PSF)
CONCENTRATED
(pounds)
4. Assembly areas
Movable seats
100m -

Source: UpCodes

The IBC also provides live load recommendations for “residential” occupancies in the same table:

TABLE 1607.1

MINIMUM UNIFORMLY DISTRIBUTED LIVE LOADS, L0, AND MINIMUM CONCENTRATED LIVE LOADSg

OCCUPANCY OR USE UNIFORM
(PSF)
CONCENTRATED
(pounds)
Private rooms and corridors serving them 40 -
Public roomsm and corridors serving them 100 -

Source: UpCodes

Given the well-documented congregational nature of students, it isn’t hard to argue that a student dorm qualifies as either an “assembly” space or a public/private room and should be designed with a 100 psf live load.

No matter what decisions are made, creating an RFI and obtaining confirmation of the assumed loads that need to be used for the building ensures that the owner, building designer, general contractor, component manufacturer and framer know that the occupancy conditions surrounding student housing have been thoroughly considered and loading conditions defined intentionally and specifically.

For additional information, please review these collapses due to overloading by crowds:

 

Check out this extra section in each digital issue of SBC Magazine for additional news, perspective, and advertiser content. Learn more and access 2016-2017 archives here.