PURPOSE:

The adoption of these revisions to the Burbank Municipal Code will modify the date for complete removal of wood roofs in the Mountain Fire Zone, revise the section regarding replacement and repairs to wood roofs and wood siding and revise the City�s fuel modification requirements (brush clearance) via a Burbank Municipal Code Amendment to the California Fire Code. The boundary line for the Burbank Mountain Fire Zone will be revised to eliminate any arbitrary jogs and inconsistencies in the present Zone border that may add possible fire hazards to adjacent properties.

BACKGROUND:

At the March 23, 2004 meeting of the Burbank City Council, Fire Chief Mike Davis made a presentation of the proposed modifications to the present requirements regarding fuel modification or brush clearance and wood shake/ wood shingle roofs and siding in the Mountain Fire Zone.  The Council requested that the modifications be clarified in regards to the restriction on wood siding and brought back to them at a future meeting. 

ANALYSIS:

I.  MATERIAL RESTRICTIONS IN THE MOUNTAIN FIRE ZONE

The intent of the revisions to the Mountain Fire Zone requirements is to minimize the available fuel load and, therefore, the ability of a fire to spread rapidly.  This will be accomplished by implementing both the brush clearance program and the restrictions on the types of materials used for exterior siding and roofing.

While the guidelines for extending the brush clearance area and the removal of exposed wood shakes and shingles are well defined, the restrictions on the selection of siding materials are dictated by additional considerations.   The following sections describe the criteria used for approving siding materials in the Mountain Fire Zone.

II.  FIRE RATING SYSTEMS

There are three fire rating systems that can be considered when identifying appropriate fire retardant materials for use within the Mountain Fire Zone.

A.  FIRE-RESISTIVE CONSTRUCTION

Fire-resistive construction is a readily recognizable standard in the construction industry.  It is common to refer to 1-hour rated walls or 20-minute rated doors.  However, this rating typically refers to a construction assembly and not to an individual product or material.  For example, a 1-hour rated wall may be constructed of several layers of fire-retardant gypsum board over 2x wood studs.  It is the combination of these materials that results in the ability of the assembly to resist exposure to fire over a period of one hour or more.  The individual materials, by themselves, are not necessarily rated and may, as in the case of wood studs, offer no fire resistance at all.  The International Code Council (ICC), Underwriter�s Laboratory UL), and other organizations test and rate the various construction assemblies.

B.  FLAME SPREAD RATING

In contrast to fire-resistive construction, the Flame Spread Rating of a material focuses on the contribution of that material to the fire�s fuel load which allows the fire to spread rapidly.  The building code specifies maximum flame spread ratings based on building use.  For example, residences have the least restrictive requirements, while assembly occupancies such as theaters have some of the most restrictive.    This is based on the concept that a residence is less hazardous than a crowded theater.  However, this also means that residences are permitted to install finish materials that are more flammable, and therefore more hazardous, than other occupancies.  

C.  FIRE CLASS RATING

The Fire Class Rating is based on a specific material�s ability to resist the effects of prolonged exposure to fire.  Class A, B, and C ratings are standard classifications for roofing materials which, in many cases, are also applied to exterior siding materials.  Basically, Class A materials are effective against severe fire exposure, Class B against moderate exposure, and Class C against light exposure. 

Rating tests utilize various sizes of wooden brands which are ignited and placed on the surface of the tested material.  The brands are allowed to burn out and the materials are examined for flammability, protection of the roof deck, slippage, and production of flying brands.  These tests are conducted under guidelines established by the International Code Council (ICC), which in turn are based on standard specifications developed by Underwriter�s Laboratories (UL).       

III.  THE PURPOSE OF FIRE RATING SYSTEMS

The purpose of each rating system varies slightly, and those differences are important factors in determining which siding materials may or may not be acceptable under the proposed revisions to Mountain Fire Zone standards. 

The purpose of establishing fire ratings for Fire-Resistive Construction, or construction assemblies, focuses on life-safety, that is, protection of a building�s occupants during a fire.  These assemblies assure the occupant�s ability to safely exit a building by protecting doors, corridors, and stairways.  Construction assembly ratings are not designed to save the structure, but only to permit the occupants adequate time to vacate that structure.  This is a critical distinction in determining acceptable siding materials.

Both the Flame Spread Rating and the Fire Class Rating, on the other hand, are designed to identify a material�s capacity to contribute to a fire�s fuel load and, therefore, contribute to the rapid spread of the fire itself.  It is this characteristic that most impacts material selection in the Mountain Fire zone   

MATERIAL SELECTION IN THE MOUNTAIN FIRE ZONE

The primary intent of the proposed code revisions is to prevent the rapid spread of a wildfire in the Mountain Fire Zone.  The critical factor in material selection, then, is to restrict the potential amounts of available fuel to prevent the fire from spreading.  Because the immediate fuel load and resulting rate of flame spread, is dictated by the exposed material rather than the overall assembly, the emphasis must be on those exposed siding materials.  For example, a 1-hour wall in a residential zone, can be constructed utilizing wood lap siding over fire-rated gypsum board.  While this assembly may not structurally fail for one hour allowing an occupant to exit safely, the exterior wood siding will nevertheless contribute to the overall fuel load.  In a mountainous area filled with vegetation, this solution becomes unacceptable.  The selection of appropriate materials must be based on either the Flame Spread Rating or the Fire Class Rating.

APPROVED MATERIALS

A.  Based on Flame Spread and Fire Class Ratings, the following siding materials can be approved for use in the Mountain Fire Zone:

          1.   Fiber-Cement Siding. 

               a.       Hazard Rating:  Class A

                      NFPA Flammability: 0 (minimal/ insignificant)

               b.       Appearance:  Fiber-Cement Siding is manufactured in planks and panels simulating both horizontal wood

                      sidingand shingle siding.

           2.  Vinyl Siding over �� Fire-Rated Gypsum Board.

                a.       Hazard Rating/ Vinyl:  Flame Spread Rating 20

                       NFPA Flammability 1  (slight)

                b.       Hazard Rating/ Gyp Board:  NFPA Flammability: 0 (minimal/ insignificant)

                c.      Appearance/ Vinyl:  Vinyl Siding is manufactured in panels simulating both horizontal wood siding and shingle

                      siding.

            3.  Aluminum Siding over �� Fire-Rated Gypsum Board.

                 a.      Hazard Rating/ Aluminum:  Non-combustible, not rated.

                 b.    Appearance/ Vinyl:  Vinyl Siding is manufactured in panels simulating both horizontal wood siding and shingle

                       siding.

B.  Based on Flame Spread and Fire Class Ratings, the following siding materials cannot be approved for use in the Mountain Fire zone:

1.  Wood Siding- Traditional solid wood siding 

•  Hazard Rating:  Flame Spread 65 � 200

2. Hardboard Siding- Multifiber or pressed wood type siding

• Hazard Rating:  Flame Spread 76 � 200

3. Engineered Wood Siding- Plywood panel siding

• Hazard Rating:  Flame Spread 76 � 200

4. Intumescent Paints, Coatings, and Other Fire Retardant Treatments.

• Because physical damage, repairs and maintenance, alterations, and exposure to weather may reduce or eliminate the effectiveness of these products, they will not be approved as alternative fire protective options in the Mountain Fire Zone.

C.  Alternative materials will be considered individually based on ICC Evaluation Reports, UL Testing Reports, Material Safety Data Sheet (MSDS) information, and other documentation provided by a third party testing agency.  Documentation from manufacturers only will not be approved for use in the Mountain fire Zone.  Approval of alternate materials will be by the Fire chief and the Building Official.

SUMMARY:

The proposed changes are as follows:

1. No roof covering shall be applied over existing wood shake or wood shingle roofing.

2. Roofs with two or more layers of roof covering, in which one of those layers is wood shake or wood shingle, must be completely removed before applying a new roof covering.

3. For all property owners with currently covered wood roofs, 1 or 2 layers, the deadline to remove and replace all the roof coverings remains August 14, 2012.

4. All exposed wood roofs in the Mountain Fire Zone shall be removed and replaced by August 14, 2005.  The current deadline to remove all wood shake and shingle roofing is August 14, 2012.

5. In the Fire Mountain Zone the allowable replacement of wood shingle siding with a one hour underlay and treated shingles or shakes is to be eliminated.

6. Mountain Fire Zone boundary line shall be revised to include additional areas that presently have been arbitrarily excluded from the Mountain Fire Zone. The map of the Burbank Mountain Fire Zone is referred to in BMC Section 7-1-3601 and is on file in the Office of the Building Official. 

7. All City owned property within the Mountain Fire Zone shall continue to have native brush areas modified to provide clearance from structures to a minimum of 100 feet and immediately add a fuel modification zone from 100 feet to 200 feet from all structures. This change has been approved and funded by City Council and work is in progress.

8. All privately owned property within the Mountain Fire Zone shall continue to have native brush areas modified to provide clearance from structures to a minimum of 100 feet and shall be required to add a fuel modification zone from 100 feet to 200 feet from all structures by June 1, 2004.

9. Fuel modification / brush clearance must conform to the California Fair Plan Standards in all cases.

10. No wood shakes or wood shingles shall be installed as an exterior wall covering on any     new or existing building or structure. No wood board, hardboard, or engineered wood siding shall be installed as an exterior wall covering on any new or existing building or structure in the Mountain Fire Zone. Pressure treated wood, intumescent paints, and other protective coatings shall not be allowed in the Mountain Fire Zone. The following types of siding may be used: Fiber-Cement siding with a Class �A� fire rating, Vinyl siding with a maximum flame spread of 25 as defined in Table 8-A of the California Building Code. Such vinyl siding shall be installed over 1- layer of Type �X� gypsum board with a minimum thickness of ��. Alternate siding materials, not mentioned, may be used when approved by the Building Official and Fire Chief in accordance with Section 104.2.8 of the California Building Code.

STAFF RECOMMENDATION:

The staff recommends that the City Council adopt the revisions, as written, with authorization for the City Clerk to publish the revisions to Sections 7-1-1405 and 7-1-1503 of the Burbank Municipal Code relating to the installation and maintenance of wood shake / shingle roofing and siding and the Burbank Municipal Code Section 15-1-1103 Amendment to the California Fire Code creating an additional 100 foot fuel modification zone for a total 200 foot protection zone within the Mountain Fire Zone.