HomeMy WebLinkAboutCode Compliance Narrative - Gorsuch Hause 2020-09-08
4445 Northpark Drive, Suite 204,
Colorado Springs, CO, 80907 USA
O:+1 720-441-6608
September 8, 2020
Christian Barlock
Principal
4240 Architecture Inc.
3507 Ringsby Court, Suite 117
Denver, Colorado 80216
RE: Gorsuch Haus – Aspen, Colorado
Code Compliance Narrative (DRAFT)
The proposed Gorsuch Haus project is a commercial residential (hotel and condominium) hospitality facility in Aspen,
Colorado. The building design covers a footprint of approximately 26,000 square feet and is generally four stories above
adjacent grade with several sub-grade floors housing parking and support/amenity spaces. Located on sloping terrain, the
building will maintain a consistent height above the adjacent grade but will increase in overall height as the grade elevation
rises.
Jensen Hughes has been asked to evaluate the proposed design and outline fundamental code-related building
characteristics in addition to specific code provisions applicable to the project that require some level of adjudication, owing
to the design’s unique character. The proposed design is unique in that full conformance with the prescriptive provisions of
the code will mandate some safeguards where no hazard exists while other hazards, specific to the project, may be
unmitigated. The project is subject to the 2015 International Building Code (IBC) as amended and adopted by the City of
Aspen and the 2015 International Fire Code (IFC) as adopted by the Aspen Fire Protection District.
The provisions of IBC Section 104.11 permit the authority having jurisdiction (AHJ) to approve alternative designs without
strict conformance with the code where compliance with code intent and life safety objectives can be demonstrated. This
authority is exercised in three possible ways: 1) relief from a requirement where it is demonstrated that the hazard
addressed by the requirement does not exist, 2) approving an alternative method of compliance where it is demonstrated that
the hazard addressed by the requirement can be effectively mitigated in a way other than the prescriptive code, and 3)
requiring supplemental safeguards where the prescriptive code does not address the hazard adequately.
The following narrative addresses key code provisions applicable to the project as a way to assist in the regulatory process
and to demonstrate compliance, and where equivalency by alternate is proposed, includes the specific code requirement,
associated intent, and description of how the project achieves compliance with each. Exhibit A, attached, summarizes the
same information in a matrix format.
Occupancy Classification
The facility will house both Groups R-1 and R-2 occupancies (hotel and condominium) in addition to Groups A-2/A-3 (dining
and meeting spaces) as well as Group S-2 (enclosed, below-grade parking) and various functional building support rooms
and guest amenity spaces.
The building’s various occupancies will be constructed per the provisions for mixed, nonseparated occupancies in 508.3. In
accordance with this approach, the most restrictive provisions of IBC Chapter 9 and minimum construction type determined
from the occupancies present are applicable to the entire building.
Building Height and Area
Stories. A building’s number of stories above grade is based on the location of grade plane or the finished ground level,
whichever is most restrictive (202). For this building, Levels 2 and above qualify as stories above grade resulting in the
Gorsuch Haus; Aspen, Colorado – Code Compliance Narrative 4240 Architecture
building being classified an 8-story building. Construction type for this building is driven by the number of stories above
grade, which, given the occupancies present, will require a minimum of Type I-B construction (Table 504.4).
Building Height. In a building of Type I-B construction, the maximum allowable building height is 180 feet. Building height is
measured from grade plane to the average roof height. The method for establishing the average roof height on a roof with
multiple facets as in the proposed design is not clear in the code. For this project, the average roof height was established at
the midpoint in a single theoretical plane representing the roof. The resulting building height is calculated to be
approximately 43 feet, well within the code allowable height.
Building Area. In a building of Type I-B construction, the allowable floor area per story and the total building area is unlimited
per Table 506.2.
Construction Type
Type I-B construction requires structural elements (Table 601) to be of noncombustible materials with a minimum 2-hour fire-
resistance rating (FRR) for primary structural frame, bearing walls, and floors, and a minimum 1-hour FRR for roof
construction and associated secondary members. Per Table 601, footnote c, heavy timber is permitted for roof construction
and associated secondary members.
Special Requirements Based on Use and Occupancy
High Rise - General. A high-rise building, per the current IBC definition, is a building with an occupied floor located more
than 75 feet above the lowest level of fire department vehicle access. IBC Chapter 4 contains special provisions for high-rise
buildings intended to address the life safety and fire protection challenges unique to very tall buildings (403). Such buildings
are characterized by, among other things, vertically stacked stories with a limited number of vertical routes for evacuation
and emergency responder access, a lack of exterior vertical access for fire suppression and rescue, building sway due to
wind, and opportunity for vertical smoke migration by “stack effect” through tall shafts.
The proposed design meets the technical definition of a high-rise building owing to its height variation along the length of the
sloped site, not because of vertically aligned and stacked stories. Maintaining a consistent maximum of four stories above
adjacent grade, the proposed building does not present the same hazards which the high-rise code provisions are intended
to address.
Multiple provisions within IBC 403 are only applicable to buildings greater than 120 feet or 420 feet tall. Whereas this
building has a calculated height of approximately 43 feet, code provisions applicable to buildings greater than 120 feet in
height are considered not applicable to this project and are not addressed herein. (403.2.3, 403.3.1, 403.3.2, 403.5.2,
403.6.1)
High Rise – Construction.
403.2.4 SFRM. This provision requires the bond strength of SFRM (Spray-applied Fire-Resistive Material) to be significantly
enhanced over base code requirements in very tall buildings to address conditions where SFRM adhesion is challenged due
to building sway or movement due to wind and the possibility of airborne missile impact. This code requirement was
incorporated into the code as a direct result of research conducted after the World Trade Center terrorist attacks of
September 11, 2001. Whereas this building has only four stories above adjacent grade, the conditions warranting enhanced
SFRM bond strength are not present.
403.3 – Automatic Sprinkler System. The building will be protected throughout by an automatic sprinkler system designed in
accordance with 903.3.1.1.
403.3.3 – Secondary Water Supply. The secondary water supply requirement is applicable to Seismic Design Cat. C, D, E,
or F. Seismic Design Category is yet to be determined.
High Rise – Emergency Systems.
403.4.1 – Smoke Detection. Full prescriptive compliance will be provided. Area detection is required in non-sprinklered
mechanical, electrical or phone equipment rooms and in each elevator machine/control room and elevator lobby.
Gorsuch Haus; Aspen, Colorado – Code Compliance Narrative 4240 Architecture
Mechanical, electrical, and phone equipment rooms are sprinkler protected and elevator machine/control rooms and elevator
lobbies will be detected.
403.4.3 – Standpipe Systems. Full prescriptive compliance will be provided. A standpipe system is required in a building
where the highest occupied story is more than 30 feet above the lowest level of fire department vehicle access (905.3.1). A
Class I standpipe system will be required per 905.3.1, Exception 1.
403.4.4 – Voice/Alarm Communication System. Full prescriptive compliance will be provided. Emergency voice/alarm
communication system per 907.5.2.2 will be provided.
403.4.5 – Emergency Responder Radio Coverage. Full prescriptive compliance will be provided. Emergency responder
radio coverage per IFC 510 will be provided.
403.4.6 – Fire Command Center. A fire command center (FCC) will be provided in accordance with the requirements of
Aspen Fire District.
403.4.7 – Smoke Removal. Full prescriptive compliance will be provided. Smoke removal will be accommodated by fixed
clearable glazing.
403.4.8 – Standby and Emergency Power. Standby power is prescriptively required for: FCC power and lighting and
elevators. Emergency power is prescriptively required for: exit signs and means of egress lighting, elevator car lighting,
voice/alarm communication system, and fire detection/alarm systems.
High Rise – Means of Egress.
403.5.1 – Remoteness of Exit Stairways. Full prescriptive compliance will be provided. Distance between required stairs will
be minimum 30 feet or ¼ the diagonal of the space served.
403.5.3 – Stairway Door Operation. Full prescriptive compliance will be provided. Stairway doors will not be locked from the
stairway side.
403.5.3 – Stairway Communication System. Full prescriptive compliance will be provided. A Stairway communication
system is required when the stair doors are locked on the stair side. Stair doors will not be locked from the stairway side.
403.5.4 – Smokeproof Enclosures. Exit stairs serving floors greater than 75 feet above the lowest level of exit discharge are
required to be smokeproof enclosures. In this design, the tallest stair does not serve an occupied story greater than 75 feet
above the lowest level of exit discharge.
403.5.5 – Luminous Egress Markings. Luminous egress markings are required in high rise interior exit stairs where
enhanced vertical egress efficiency is mandated due to protracted egress durations within extremely tall interior stairs and
where the possibility of catastrophic electrical failure due to a single event exists. This code requirement was incorporated
into the code as a direct result of research conducted after the World Trade Center terrorist attacks of September 11, 2001.
The egress design of the Gorsuch Haus requires interior exit stair travel through no more than four floors from any part of the
building before reaching required access to the building exterior, performing no differently than a four-story building with
regard to the intent of luminous egress markings. Luminous egress markings are not proposed for this design insofar as the
perils that merit them in high rise exit stairs do not exist with this egress arrangement.
Fire Protection Systems
Fire Alarm. A manual fire alarm system is required residential (Group R-1) occupancies with smoke detection required in all
interior corridors serving sleeping rooms, common areas, laundry rooms, and mechanical rooms (907.2.8, 907.2.8.2
amendment). A manual and automatic (by amendment) fire alarm system is required in Group R-2 and Assembly
occupancies (907.2.9, 907.2.1).
Means of Egress
Each floor is served by a minimum of two exits as required by IBC 1006.3.2. The exits provided are either interior exit stairs
or exterior doors leading to exterior exit stairs. On all stories above the street level (Level 1) the two required exits route
egressing occupants to opposite sides of the building, that is, one exit routes to the east building exterior and the other to the
Gorsuch Haus; Aspen, Colorado – Code Compliance Narrative 4240 Architecture
west building exterior. Once outside the building, occupants travel north at or nominally at grade along a cascading stair that
discharges at the public way. Normally, such an exterior stair is classified and regulated as exit discharge. However, due to
site constraints, the exit discharge is not able to achieve the dimensional requirements of IBC 1028.2. As a result, the
exterior stairs are designed and protected as required for exits, specifically exterior exit stairs.
Exterior Exit Stairs.
1027.5 – Location. Exterior stairs are required to have a minimum fire separation distance of at least 10 feet from adjacent
lot lines. Due to site constraints, a 10-foot fire separation distance for the exterior exit stairs cannot be accommodated.
Additionally, one objective of the project’s functional program is to provide unrestricted visual and physical access to the
adjacent lots, something that a physical barrier at the property line would conflict with. As an alternative, compliance with the
intent of 1027.5 will be achieved by the establishment of approved legal instruments restricting use of the adjacent parcels
sufficient to achieve equivalent protection to the prescribed fire separation distance.
1027.6 – Exterior exit stairway protection. The exterior exit stairways will be separated from the interior of the building in
accordance with the provisions of 1027.6.
Exterior exit stairs are not permitted in the means of egress from a high rise building or a building with more than six stories
above grade plane (1027.2). The restriction on using exterior exit stairs for egress from tall buildings is in recognition that
egress can be affected by occupants experiencing the effects of vertigo induced by the fear of a shear fall from a great height
from the stair. A fall down a stair run is not contemplated by this provision and is otherwise addressed by the requirement to
interrupt vertical stair rise by landings at no less than twelve-foot intervals (1011.8).
While the building meets the high-rise definition only in technical terms, it is no more than five stories above grade plane by
calculation and the stairs’ walking surface is nominally at grade for its entire length. The exterior exit stairs serving this
building do not present the same fall threat intended to be addressed by 1027.2 and will serve the code-required purpose
accordingly.
Exterior Walls
Exterior Wall Covering. Exterior wall covering, as regulated by the IBC, includes veneers, siding, cornices, soffits, and facias
(202). In a building of Type I-B construction, combustible exterior wall coverings are permitted but are limited to a maximum
of 40 feet above grade plane (1406.2.1, 2). Combustible exterior wall coverings constructed of fire-retardant-treated wood
are permitted up to a height of 60 feet above grade plane (1406.2.1, 3). Where located more than 60 feet above grade
plane, exterior wall covering is required to be non-combustible.
Balconies. Exterior balconies are limited to a maximum of 50 percent of the building’s perimeter on each floor (1406.3)
unless sprinkler protection is extended to the balcony areas (1406.3, Exception 4). Balconies made of combustible
construction are required to be Type IV, heavy timber construction or have a minimum 2-hour FRR (1406.3). Guards,
pickets, rails, and similar guardrail devices are permitted to be of untreated wood (1406.3, Exception 2).
If you have any questions regarding this evaluation or would like to discuss further, please feel free to contact me directly at
jevans@jensenhughes.com or 719-314-7381.
Sincerely,
JENSEN HUGHES
Jeffrey Evans, RA, CBO