Open to Below: A Discussion of Allowed Floor Openings Kevin S. Hastings, P.E., LEED AP Jay A. Ierardi, Ph.D., P.E., LEED AP R.W. Sullivan Engineering (617) 523-8227, Fax (617) 523-8016 http://www.rwsullivan.com
Welcome The Boston Society of Architects/AIA is a Registered Provider with The American Institute of Architects Continuing Education Systems. Credit earned on completion of this program will be reported to CES Records for AIA members. Certificates of Completion for non-aia members are available on request. This program is registered with the AIA/CES for continuing professional education. As such, it does not include content that may be deemed or construed to be an approval or endorsement by the AIA of any material of construction or any method or manner of handling, using, distributing, or dealing in any material or product. Questions related to specific materials, methods, and services will be addressed at the conclusion of this presentation.
Learning Objectives Every floor opening is not an atrium! 780 CMR 713.3 and 707.2 provide specific exceptions. Architectural solutions to reduce or eliminate mechanical smoke exhaust. Basic understanding of performance-based approaches to floor openings and smoke control.
R.W. Sullivan Engineering (RWS) was established in 1945 and currently has over 85 employees. RWS is a full service engineering i firm offering integrated services in the following disciplines: i HVAC Electrical Plumbing Fire Protection Code
Agenda Floor Opening Protection Codes 780 CMR: MA State Building Code, 6 th Edition (1993 BOCA) International Building Code, 2003 Edition (780 CMR 7 th Edition) International Building Code, 2009 Edition (780 CMR 8 th Edition) NFPA 101: Life Safety Code NFPA 92B: Smoke Management Systems Types of Floor Openings General 2-Story Floor Openings 3+ Story Floor Openings Atriums Other Permitted Unenclosed Openings Performance Based Approaches
General Floor Openings Shaft Enclosures 780 CMR, IBC, and NFPA 101 require floor openings comply with one of the following: 1 hour rated shaft when connecting 2 or 3 floors. 2 hour rated shaft when connecting more than 3 floors. Meet an exception for an allowed floor opening.
2-Story Floor Openings
2-Story Floor Openings Code Code Section Prohibited Uses Used for Egress Required Separation 780 CMR 713.3 6 th Edition Exception 2 IBC NFPA 101 707.2 Exception 7 None Use Group I-2 & I-3 8.6.8.1 None 8.6.8.2 Unsprinklered Assembly Not Corridors in Use Group I & R Permitted All Unsprinklered Corridors Permitted Not Permitted Not Permitted Corridors in Use Group I & R All Unsprinklered Corridors One of the Floors All Corridors
2-Story Open Exit Stairs 780 CMR (7 th Edition) Section 1019.1 & 2009 IBC Section 1016.1 Exception 8 allows for 50% of the exit stairs between any 2 stories to be unenclosed and used as an exit stair. This stair however cannot be open to more than the two connected stories. 1 Hour Wall
2-Story Open Exit Stairs 780 CMR (7 th Edition) Section 1019.1 & 2009 IBC Section 1016.1 Exception 9 allows for all exit stairs between the first 2 stories to be unenclosed and used as exit stairs in a fully sprinklered building. The connected floors must have 2 exits and are not permitted to be open to any other floors.
Multiple 2-Story Floor Openings 4 th floor 3 rd floor Rated assemblies 2 nd floor Boundaries of floor openings 1 st floor
2-Story Floor Openings Alternative Approach 3 rd floor Sprinkler Protected Glazing or Rating Equivalent to Floor 2 nd floor 1 st floor Alternative design requires approval from the Authority Having Jurisdiction or a variance. Provides smoke reservoir that performs better than a continuous floor assembly.
3+ Story Floor Openings
3+ Story Floor Openings Size Code Code Section Restrictions Required Separation Limits 780 CMR 6 th Edition 713.3 Exception 11 Business Stairs Unsprinklered Buildings Only Use Group B 6 Floors Max Draft Curtains w/ Closely Spaces 160 ft 2 Sprinklers All Corridors NFPA 101 IBC 8.6.8.6 Escalators only No more than 4 stories in Use Groups B & M w/ sprinkler option Twice the Escalator Area Draft curtains w/ closely spaced sprinklers OR Shutter at every floor opening 713.3 Exception 8 Escalator opening 780 CMR 7 th Edition & IBC 707.2 Exception 2 Escalator /Open Stair Unsprinklered Buildings 4 Floors Max in Use Groups other than B & M Twice the Stair Area Draft Curtains w/ Closely Spaces Sprinklers NFPA 101 IEBC 8.6.6 Mini-Atrium 703.2.1 Unsprinklered Educational All Healthcare Unsprinklered Apartments Lowest or Next to Lowest Level must be a Street Floor No more than 3 Floors None Smoke Barriers Adjacent spaces have access to an exit without entering the communicating space.
Escalator / Open Stair Protection ti 780 CMR 713.3 Exc. 8, IBC 707.2 Exc. 2, NFPA 101 8.6.8.6 Openings protected with a draft curtain and closely spaced sprinklers. The opening area is limited to twice the horizontal projected area of the escalator. Also, 780 CMR and IBC limit openings to not more than 4 stories in Use Groups other than B & M.
Escalator Protection for Open Stairs NFPA 101 The Manual Escalator. Same hazard as an escalator, however only 780 CMR 7 th Edition and IBC permit the use of the previously described options for protecting a standard open stair. Approval from the Authority Having Jurisdiction or a variance is required for states adopting NFPA 101.
Mini-Atrium: Configuration NFPA 101 8.6.6 & IEBC 703.2.1 Exception 3 Connects no more than 3 stories (Not Limited by IEBC) Lowest or next-to-lowest floor is street level Open and unobstructed communicating space
Mini-Atrium: Fire Protection NFPA 101 8.6.6 & IEBC 703.2.1 Exception 3 NFPA Fire Separation Options 1 hr fire barrier Smoke barrier in a fully sprinklered building No separation required for detention/correction housing IEBC Fire Separation Smoke Barrier
Mini-Atrium: Egress NFPA 101 8.6.6 Considered a single floor area for egress capacity Occupants within the mini-atrium access to at least one exit without t having to traverse another story within the mini-atrium space Occupants outside the mini-atrium access to at least one exit without having to enter the mini-atrium space
Other Permitted Unenclosed Openings Section 707.2 4 story opening within a dwelling unit (780 CMR Exception 1 & IBC Exception 1) Malls (780 CMR Exception 5 & 2003 IBC Exception 5) Mezzanines (780 CMR Exception 9 & IBC Exception 9) Ramps in parking structures (780 CMR Exception 8 & IBC Exception 8) Use Group I-3 in accordance with 780 CMR 410.5 (780 CMR Exception 7)
Atriums
Atriums 780 CMR & IBC 404, NFPA 101 8.6.7 General requirements Sprinkler Protection: Atriums must be protected with sprinklers (780 CMR 404.2, IBC 404.3, NFPA 101 8.6.7(4)). Travel Distance: Other than the lowest floor, the egress travel distance through an atrium is limited to 150 ft (780 CMR 404.7) or 200 ft (2009 IBC 404.9). Exit Discharge: Permitted within the atrium (780 CMR 404.3.1, NFPA 101 8.6.7(2)).
Enclosure of Atrium 780 CMR & IBC 404.5, NFPA 101 8.6.7(1) Atriums are required to be separated from adjacent spaces by 1 hour rated construction except: Residential guest rooms or dwelling units where egress is provided that does pass through the atrium (780 CMR only). 3 stories are permitted to be open to the atrium if the volume calculated for the design of the smoke control system includes the volume of the spaces not separated from the atrium. (No limit in NFPA 101) Sprinkler protected glass
Sprinkler Protected Glass
Atrium Smoke Control 780 CMR 404.4 & IBC 404.4 Smoke control is required in all atriums that connect more than 2 stories ( connect = opening in floor slab).
Smoke Control Design Criteria Component Interface height above highest walking surface open to the atrium 780 CMR 6 th Edition Design fire size 2000 BTU/s Fire scenarios Axisymmetric 780 CMR 7 th Edition & 2003 IBC NFPA 101 / 92B 2009 IBC 6 ft. 10 ft. 6 ft. 5000 BTU/s minimum Axisymmetric, Balcony Spill, Window Determined by Analysis Axisymmetric, Balcony Spill, Window
Example Atrium
Example Exhaust Rates Code Exhaust Requirement (cfm) 6 th Edition: Axisymmetric * 226,508 Code Exhaust Requirement (cfm) 7 th Edition: Axisymmetric ** 332,891 7 th Edition: 15 Wide Balcony Spill 636,890 7 th Edition: Window Spill Plume 158,658 7 th Edition 636,890 The same variables were used in both axisymmetric cases except for fire size. * Calculated with a 2,000 Btu/s fire as required by 6 th Edition. ** Calculated with a 5,000 Btu/s fire as required by 7 th Edition.
Exhaust Rates Exhaust Requirement (cfm) Open Floors 780 CMR 6 th 780 CMR 7 th Edition Edition & IBC 1 thru 5 195,927 667,559 1 thru 4 138,313 487,593 1 thru 3 89,269 337,603 1 thru 2 49,631 187,613 1 8,604 35,948
Performance Based Approaches Due to the large exhaust rates under IBC alternative designs will likely become more common. 780 CMR 7 th Edition permits alternative designs for smoke control systems (780 CMR 909.20.4). A 3 rd party review and variance is currently required for all alternative designs in Massachusetts (780 CMR 901.7.2.1). 2009 IBC references NFPA 92B which allows CFD modeling
Alternative Design Examples Shutters / Curtains Used to enclose the upper stories of an atrium. Activated by building fire alarm system. Egress Access to required exits outside the atrium boundary Fire Modeling Used to estimate actual smoke production and spread. Deluge Sprinkler System Used to limit the fire size.
Atrium Egress Access to required exits without entering the atrium and allowing the smoke to lower down.
Atrium Fire Modeling
Atrium Fire Modeling Plugholing Relatively shallow smoke layer depth and a high exhaust rate can lead to the entrainment of cold air from the clear layer.
Alternative Protection Example Life Sciences Laboratory Building 2-story floor open (shown in red) Designed as an atrium per NFPA 101 No smoke control provided based on analysis
Alternative Protection Example
Visibility and Smoke Movement: Floor Opening in a University Building 208 ft 154 ft
Thank you. This concludes The American Institute of Architects Continuing Education Systems program. QUESTIONS? Kevin S. Hastings, P.E., LEED AP Jay A. Ierardi, Ph. D, P.E., LEED AP KSH@RWSullivan.com JAI@RWSullivan.com 617.337.9319 617.337.9321 Please email us for a PDF file with full-size slides of this presentation.