Discussion: View Thread

Expand all | Collapse all

Design for Fire Resistance

  • 1.  Design for Fire Resistance

    Posted 12-03-2018 03:00 PM
    Edited by Tirza Austin 12-03-2018 02:59 PM
    ​Hurricanes devastate entire communities.  In response, we have structural requirements for wind loading and flood resistance (ASCE 7 and 24, for example).  Not to mention requirements for buildings being elevated above base flood elevation.  For seismic design we have many building requirements.  But what about fire resistance?  The disaster in Paradise, California affected more people for a longer time than most if not all modern earthquakes, and wiped out an entire small city.  Most of the trees surrounding the destroyed buildings remain standing and living, so the devastation is not a consequence of a dense tree canopy.  Why were not these buildings more fire-resistant?  How can we make communities more fire-resilient?  Why do building codes allow unprotected wood-frame and burnable roofing materials in regions adjacent to dry, heavily wooded wildlands?   The initial cause of the Camp wildfire in Butte County, California is irrelevant;  if it had not have been one reason there could have been another reason for the fire to have started. What can civil engineers do to build resiliency?

    Dudley McFadden P.E., D.WRE, M.ASCE
    Principal Civil Engineer
    Sacramento Municipal Utility District

  • 2.  RE: Design for Fire Resistance

    Posted 12-04-2018 10:11 AM
    Edited by Tirza Austin 12-04-2018 10:10 AM
      |   view attached
    ​You are right Sr., the first thing to have in mind is why building permits are allowed in those risky places? The second thing to ask is why concrete or stone or even steel construction is not used instead of wood construction? The steel and concrete design for fire is more advanced (see link below) but regardless of that, survive in a natural disaster like that you can not give it for granted, even if you design for fire the most you can get is an opportunity to escape. 


    Roberto Nava Cuellar P.E., M.ASCE
    Monterrey, Nuevo Leon
    5281 41626756


  • 3.  RE: Design for Fire Resistance

    Posted 12-04-2018 12:12 PM
    Edited by Tirza Austin 12-04-2018 12:11 PM
    NFPA 1 National Fire Protection Standards covers requirements for fire resistance requirements for buildings and structures.  This code like other codes is updated every three years.  Requirements in this code are based on the use of and occupancy level of the building.  The code is written to insure that occupants can safely exit the building in case of a fire.  Critical buildings must meet stricter standards than other buildings and structures.  The code will not insure that buildings will survive wild fires.

    Kenneth Clark P.E., M.ASCE
    Civil Engineer
    Oklahoma City OK
    (405) 416-8187

  • 4.  RE: Design for Fire Resistance

    Posted 12-04-2018 01:42 PM
    Edited by Tirza Austin 12-04-2018 01:41 PM
    Older structures will always be more vulnerable, but even newer structures have so far not been required to address the risks seen in these areas.  The current building codes are written primarily looking at fires originating within the structure.  The building setbacks that address exterior sources are based on the assumption of a fire in a neighboring structure with adequate fire fighting response.  Maybe it is time for more jurisdictions in areas vulnerable to wildfires to reassess their minimum standards.  Conventional Wood Frame construction is perfectly capable of being fire resistant, but it requires the appropriate requirements be written into the codes.  Many of the paths of ignition are known, and can be addressed by the proper construction requirements.

    Mark Myers, P.E., M.ASCE
    Gig Harbor, WA

  • 5.  RE: Design for Fire Resistance

    Posted 12-10-2018 01:52 PM
    I agree with Mr. Myer's comment. It seems to me also that main focus of fire protection provisions in building codes is to control the spread of a fire originating inside a building to adjacent buildings. Fire resistance ratings for exterior walls in IBC Table 601 and 602 are determined with this focus and assume a fire load that could be controlled by fire fighters' response.

    For example, load bearing walls in Type V construction and occupancy group R shall be 1-hr rated per Table 601. However, section 705.5 of the code allows exterior walls to be rated for exposure to fire from the inside (only), if the fire separation distance is greater than 10 ft. My interpretation is that typical residential construction would not have exterior load bearing walls rated for an exterior fire exposure, unless the fire separation is less than 10 ft, which is not the case for most homes built in the wilderness. 

    Please correct me if my interpretation of the code is wrong. Perhaps a minimum fire rating for exterior fire exposure could be introduced for type V construction in the proximity of wilderness areas?

    Luca Magenes P.E., M.ASCE
    Powell Industries, Inc.
    Houston TX

  • 6.  RE: Design for Fire Resistance

    Posted 12-08-2018 09:54 AM
    Edited by Tirza Austin 12-08-2018 09:53 AM
    Besides being more expensive concrete and stone have other problems.  Stone and often concrete construction is problematic when you are concerned about earthquakes. 

    Is it better to have safer buildings that are more expensive thus making it harder for many people to afford housing?  Be sensitive to the tradeoffs made by different societies.

    Mark Gilligan S.E., M.ASCE


  • 7.  RE: Design for Fire Resistance

    Posted 12-06-2018 09:52 PM
    Edited by Tirza Austin 12-06-2018 09:52 PM
    First resiliency is a term that has many definitions and thus in effect has no meaning unless you clarify what you mean.

    In response to the question of what can civil engineers do to improve performance when exposed to fire, the basic answer is to be available to assist those who take the lead.  In our current system on projects Architects take the lead with respect to selecting the fire protection strategy and in addressing fire protection issues.  The civil engineers typical role with respect to fires is to assist.

    The decision to build out of wood is driven by cultural and economic considerations.

    To suggest that you shouldn't build in these forested regions seems to ignore the reality that it is common throughout the country to build housing in close proximity to forests.  If this were not allowed many portions of the country would be depopulated.  Fire protection is not the only concern.  We need solutions that  look at the problem from a systems point of view.

    We need to appreciate that the civil engineer typically does not have the authority to change things.  We cannot always be the savior.  We also should appreciate that with rare exceptions civil engineers do not  have any real expertise with regards to fire resistance and protection.  We need to keep this fact in mind if we have urges to take leadership in proposing changes.

    As engineers we are expected to only comment when we have expertise.  As a member of the public we can say whatever we want.

    Could it be that the smoke and carbon released be a bigger concern since it may impact the warming of the planet?  If that is the case then the proposed solutions will have little long-term impact unless we can stop fires from occurring.

    Mark Gilligan P.E., M.ASCE
    Berkeley CA
    (510) 548-8029

  • 8.  RE: Design for Fire Resistance

    Posted 12-07-2018 12:59 PM
    Edited by Tirza Austin 12-07-2018 12:58 PM
    Several opinions in response to Mr. Gilligan's comments:

    1. The question is normative. Americans have often built in wooded areas; this does not give us license to always build anything anywhere.
    2. Engineers are disproportionately influential in shaping building codes, especially in participation with ASCE, AISC, etc.. Strategic-level regulation of building practices based on fire susceptibility is possible (Rancho Santa Fe, San Diego County). Building Codes have this power--as the OP mentioned, we do not design for equivalent wind speed across the country.
    3. Regardless of our legal responsibilities, we cannot knowingly design unsafe buildings. It is easy to forget that professional ethics are a subset of ethics.

    I understand that Mr. Gilligan's opinion comes from experience. However, we must also be proactive in creating change where the status quo has failed. We do not need to be the savior, but we can be on the right side or not.

    Christian Parker EIT, A.M.ASCE
    Structural Project Engineer
    Washington DC
    (202)628-1600 EXT 190

  • 9.  RE: Design for Fire Resistance

    Posted 12-08-2018 09:53 AM
    Edited by Tirza Austin 12-08-2018 11:12 AM
    I never said you should be able to build anything anywhere.  Just consider the implications of what is being proposed.  

    Civil engineers do not have a significant influence in shaping building codes with respect to fire resistance and fire protection.  If there will be change then I suggest that it will come from those with the expertise.  If you want to shape that discussion then I suggest that you understand the science of fire engineering but if  you develop real expertise I suggest that you will do so at the expense of developing your expertise as a civil engineer.

    I Suggest that you read the provisions in the IBC related to fire resistance and protection.  Then read the fire code.  By the way many, parts of the country have no building code and in many more enforcement is lax. In many parts of the country building codes are very much a local thing.

    You say we cannot knowingly design unsafe building but what is an unsafe building?  All buildings have risks, how much risk is too much?  If you are saying that current building codes allow unsafe buildings then you are saying that most engineers are designing unsafe buildings.  Should ASCE sanction most of its members?

    I would suggest that it would be irresponsible for a civil engineer to tell a client that their building was perfectly safe.  Look in ASCE 7-16 where it explicitly recognizes that our codes are based on an acceptance of risk.

    It is easy to adopt distorted interpretations of the ASCE code of ethics.  Be careful. 

    Mark Gilligan S.E., M.ASCE


  • 10.  RE: Design for Fire Resistance

    Posted 12-07-2018 08:49 AM
    Edited by Tirza Austin 12-07-2018 08:49 AM
    California has a specific code for wildfire resistant construction  The question is why is it not mandatory in certain locations? I've been providing wood-framed designs in CA for many years and have yet to be required to follow the Wildfire code

    Robert R Desmarais Jr, PE
    rrd pe corp
    313 West Liberty Street, Suite 101
    Lancaster, PA 17603

  • 11.  RE: Design for Fire Resistance

    Posted 12-07-2018 01:03 PM
    Edited by Tirza Austin 12-07-2018 01:02 PM
    I think the primary reasons for the lack of increased fire resistance are cost and tradition.  It's more expensive to build a home out of concrete, masonry, or steel.  Both for materials and for the labor, typically.  In addition, the residential trades related to the building structure consist mostly of contractors specializing in concrete for foundations and wood framing for walls, floors, and roofs.  Finally, the IRC is heavily focused toward these approaches to construction bringing additional challenges in documenting, permitting, and approval for alternative construction types.

    Integration of increased fire protection on any large scale into the residential construction requirements (IRC or some other secondary adopted standard) would be ruthlessly opposed, particularly those responsible for the construction since most of the cost for implementation will be left with them.  And, since real estate prices are generally established by total square footage, most people would be willing to pay little or nothing for these added safety benefits as they would personally see no impact in their day-to-day use. Sure, insurance premiums may be lower, but the time to break even on the initial investment would be so far in the future that it would be impractical or impossible to ever really recoup these costs.  So, for these reasons, like most efforts for code change, if it increases cost and breaks with tradition, it will be opposed.  It's the unfortunate reality in my experience.

    Cliff Jones P.E., S.E., M.ASCE
    Jensen Hughes
    Portland OR

  • 12.  RE: Design for Fire Resistance

    Posted 12-07-2018 04:18 PM
    Edited by Tirza Austin 12-07-2018 04:17 PM
    The International Wildland-Urban Interface Code (International Code Council) provides requirements for the design and construction of buildings with a potential exposure to wildfires.  This code must be adopted by the authority having jurisdiction before it's requirements are mandated, but that does not prevent the building's designer from applying some or all of the requirements in order to increase the building's resistance to a wildfire.

    Gary Walker P.E., M.ASCE
    Walker Engineering, Inc.
    Birmingham AL
    (205) 854-0160

  • 13.  RE: Design for Fire Resistance

    Posted 12-09-2018 09:01 AM
    Edited by Tirza Austin 12-09-2018 09:00 AM
    Why is no one referencing “How to Design And Build Disaster Safe Homes” by Joseph C.E. Warnes? It is an exiting concept. It is my option that the Lumber Lobby, like most lobbies have too much influence. I have read the book & referenced ASCE-7, ASCE-7-98 & ASCE-7-5. These homes can be built with ceramic panels fastened to the panels during fabrication. I am no expert in this. Although, I worked for a fabricated home manufacturer. Just a suggestion.

    Robert Perugini

  • 14.  RE: Design for Fire Resistance

    Posted 12-09-2018 09:46 PM
    Edited by Tirza Austin 12-09-2018 09:46 PM
    Mr. Warnes seems to promote the use of engineered concrete buildings.  

    Any solution that does not consider the context in which the building will be built is questionable.  People want a building that is affordable.  They want a building that looks like what they believe a house should look like.  These and other considerations will often result in individuals accepting some risk.

    Probably more lives would be saved if nobody exceeded the speed limit when driving.

    We can inform our clients of the risks but is it our right to tell them that they cannot accept some risk?  Yes, there are situations where the risks are too great and we need to say no, but I will suggest that those are extreme cases.  As a professional we have an obligation to help our client meet their needs.

    Consider this as a multidimensional problem.  Understand the non-engineering dimensions.

    Mark Gilligan P.E., M.ASCE


  • 15.  RE: Design for Fire Resistance

    Posted 12-16-2018 06:38 PM
    Edited by Tirza Austin 12-16-2018 06:38 PM
    I know Mr. Warnes, having reviewed the referenced paper for him.  He is really advocating for complete concrete shells as a proven way to resist wind, fire and seismic events.  This goes back to the 1960's when the US built simple ranch-style single family all-concrete homes in Guam which have survived many typhoons.  The key is the concrete roof tied to the concrete walls tied to the foundation slab.  This can be codified just like wood frame construction is today.

    I live in SW Florida and DiVosta builds very affordable homes with poured concrete walls now.  They just don't do the roof, yet, so guess what gets damaged in the hurricane?  I was in Belize a few years ago and they form the roofs in concrete for all types of housing.

    Finally, the question of "affordable" is about to be changed by the insurance industry when they raise the rates on any type of frame construction that did poorly in these hazardous areas.  Once the builders get used to a new system and can set up to build multiple homes, it will become part of the new "vocabulary."  It is a multidimensional problem.

    Alvin Ericson Aff.M.ASCE
    Technical Consultant
    Alvin Ericson - Technical Consultant
    Bonita Springs FL
    (239) 948-1771

  • 16.  RE: Design for Fire Resistance

    Posted 12-08-2018 11:09 AM
    Edited by Tirza Austin 12-08-2018 11:09 AM
    In a recent study "Unraveling the Complexity of Wildland Urban Interface Fires" we argued that a holistic framework is needed to evaluate community risk to wildfires and have highlighted the criticality of including community-specific characteristics such as the interface with the wildland, buildings layout, and local wind speed and direction in the community. We also noted that proper statistical treatment of the parameters controlling these characteristics have to be realized for accurate assessment of risk. These parameters essentially influence wildland ignition probability and community vulnerability, which once calculated, they can be combined to evaluate community risk.  

    Unraveling the Complexity of Wildland Urban Interface Fires
    Scientific Reports remove preview
    Unraveling the Complexity of Wildland Urban Interface Fires
    Recent wildland urban interface fires have demonstrated the unrelenting destructive nature of these events and have called for an urgent need to address the problem. The Wildfire paradox reinforces the ideology that forest fires are inevitable and are actually beneficial; therefore focus should to be shifted towards minimizing potential losses to communities.
    View this on Scientific Reports >

    Hussam Mahmoud Ph.D., M.ASCE
    Associate Professor
    Colorado State University
    Fort Collins CO
    (610) 758-3066

  • 17.  RE: Design for Fire Resistance

    Posted 12-22-2018 09:46 AM
    Edited by Tirza Austin 12-22-2018 09:45 AM
    Perhaps it's worth looking into precast concrete option: modular mass production for maximum affordability while maintaining the robustness inherent in concrete. That's what was used in constructing whole towns oversees. My colleagues there built a town near a new dam site, and another at a new oil field in the desert. Their European precast concrete approach used a limited number of precast concrete shapes that were assembled creatively to produce a wide variety of structures. My precast concrete practice here, in North America, was drastically different: not so much geared into building whole towns out of one precast plant. It might be worth looking into examples of town's mass production. Extra attention to connection-details would be required for structures in hurricane and/or earthquake regions.

    Neil Kazen, M.Eng., M.Sc., P.Eng.
    Retired Structural Engineering Manager, Transportation Division, SNC-Lavalin
    Toronto, Ontario, Canada

  • 18.  RE: Design for Fire Resistance

    Posted 03-25-2019 06:18 PM
    Edited by Tirza Austin 03-25-2019 06:18 PM

    I would second with Nail, however, installing fire resistance features also would be an alternative in addition to use pre-cast concrete. The current fire resistance code is suitable for unwild fire that's originated due to material burning or not installing fire sprinklers in the structures, but the code might not be sufficient in this case of wildfire and can cause devastation. It sounds what you're looking for is the primary and the secondary means to escape from the wildfire. Let us include that wildfire rate is a bit faster than your walking rate, so, it would be better to run. My suggestion is that it's important to change wild lands to domestic by clean up the trees and the bushes before become residential area.

    Sayed Maqsood
    Oakland CA