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Fire separation fire walls fire doors what you need to know | Santa Clarita

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Garage to Single family home separation is not a “FIRE WALL” | Santa Clarita

For many of us who are living in our Santa Clarita single family or multi family homes, we go about our day to day activities without knowing that there are literally thousands of building codes which make up your building’s structure.

Many of of these codes will pertain to protection and safety in at least one way or another. Those of us who are not construction minded can manage to live in our houses for years and have no idea such a plethora of building codes even exist. But rest assured, they do.

That is of course until the day arrives when you go to sell your place and are then made aware of some of these codes by the right local Santa Clarita home inspector. This is especially true if you have specific issues which involve specific code / safety systems.

Why is it Important to be Aware of Code?

Mazza Inspection Group wants buyers and sellers alike to be aware that code issues brought up during the course of the sale of the home may affect the sale. But when these issues are brought to light they can come as a complete surprise especially when they cost you real money to improve.

There are, however, some cases where the damage if significant enough may affect the loan process. I cant speak on this from any authority. I only know of this because I’ve been questioned numerous times by various lending agencies about the extent of damages we’ve reported on.

To understand which building codes apply to your specific situation, you must first determine which use classification and which ICC Building Code your specific building falls under. You will also need to determine the zoning.

First off, who the heck knows what zone they fall under? Most of us do not but the reality is, the code book which dictates the specific building codes which thus regulate the building codes for your fire separation and fire doors, will be within that book.

What are R1, R2, and R3 homeowners? What are the differences?

residential types

When referring to zoning, typically we’re referring to the type of residence it is. For UR1 normally, the house is detached. Additionally, R2 can refer be a townhouse or duplex with one attached wall.

R3 may refer to a multi unit complex such as an apartment or condominium complex. Additionally, the designations may also refer to the lot size and density, or how many structures permitted per acre.


A few years ago California adopted the ICC or international Code Council building code series. Basically there are two different building codes which apply to the three most common types of Santa Clarita housing units.

In all honesty, there are actually a few different building codes which may go into the construction of your home.

  1. CBC: The California Building Code contains regulations pertaining to practices used in commercial construction.
  2. CRC: The California Residential Code contains information and regulations applying to residential construction, including the both new construction practices as well as remodeling issues.
  3. Existing Building Code (CEBC)
  4. Mechanical Code (CMC)
  5. Plumbing Code (CPC)
  6. Fire Code (CFC)
  7. International Swimming Pool and Spa Code (ISPSC)
  8. The NFPA collection of codes and standards

Now that you know what classification you are in and thus which building codes apply to your situation, you can better determine the most applicable course of action for repairs or improvements

So what’s a “firewall”?

santa clarita home inspection
Essentially it’s it’s most basic terms, a firewall is a passive fire protection system designed specifically to stall flame spread from one building to another adjacent building. In contrast, active fire suppression methods would be sprinkler systems for example. The 2018 NFPA 221 defines a few different types of firewall systems, however, we’re only speaking about one really.

A firewall serves two purposes.

  1. Contain the fire
  2. Help protect and save the occupants

Fire wall

NFPA* Fire Wall. A wall separating buildings or subdividing a building to prevent the spread of fire and having a fire resistance rating and structural stability.

Firewalls designs have endured rigorous testing and are exposed to extreme heat for long periods of time in order to achieve a rating in minutes or hours.  

Understand, however, that the fire protection rating should not be confused with the fire resistance rating. The NFPA 221 clearly defines the differences between the protection rating vs. the resistance rating here below…

2018 NFPA 221

  1. 3.3.5 Fire Protection Rating. The designation indicating the duration of the fire test exposure to which an opening protective assembly was exposed.
  2. 3.3.6* Fire Resistance Rating. The time, in minutes or hours, that materials or assemblies have withstood a fire exposure as determined by the tests, or methods based on tests, prescribed by this standard.
Two forms of testing are performed by ASTM and UL. Here’s what the code says about testing.

California Building Code 703.3 Methods for determining fire resistance.

The application of any of the methods listed in this section shall be based on the fire exposure and acceptance criteria specified in ASTM E119 or UL 263. The required fire resistance of a building element, component or assembly shall be permitted to be established by any of the following methods or procedures:

  1. Fire-resistance designs documented in approved sources.
  2. Prescriptive designs of fire-resistance-rated building elements, components or assemblies as prescribed in Section 721.
  3. Calculations in accordance with Section 722.
  4. Engineering analysis based on a comparison of building element, component or assemblies designs having fire-resistance ratings as determined by the test procedures set forth in ASTM E119 or UL 263.
  5. Alternative protection methods as allowed by Section 104.11.
  6. Fire-resistance designs certified by an approved agency.

California Building Code 703.2 Fire-resistance ratings

The fire-resistance rating of building elements, components or assemblies shall be determined in accordance with the test procedures set forth in ASTM E119 or UL 263 or in accordance with Section 703.3. The fire-resistance rating of penetrations and fire-resistant joint systems shall be determined in accordance Sections 714 and 715, respectively.

California Building Code 703.5 Non Combustibility tests.

The tests indicated in Sections 703.5.1 and 703.5.2 shall serve as criteria for acceptance of building materials as set forth in Sections 602.2, 602.3 and 602.4 in Types I, 11, Ill and IV construction. The term “noncombustible” does not apply to the flame spread characteristics of interior finish or trim materials. A material shall not be classified as a noncombustible building construction material if it is subject to an increase in combustibility or flame spread beyond the limitations herein established through the effects of age, moisture or other atmospheric conditions.

The testing agencies


4.1 These test methods are intended to evaluate the duration for which the types of building elements noted in 1.1 contain a fire, retain their structural integrity, or exhibit both properties during a predetermined test exposure.

4.2 The test exposes a test specimen to a standard fire controlled to achieve specified temperatures throughout a specified time period. When required, the fire exposure is followed by the application of a specified standard fire hose stream applied in accordance with Practice E2226.

The test provides a relative measure of the fire-test-response of comparable building elements under these fire exposure conditions. The exposure is not representative of all fire conditions because conditions vary with changes in the amount, nature and distribution of fire loading, ventilation, compartment size and configuration, and heat sink characteristics of the compartment.

Variation from the test conditions or test specimen construction, such as size, materials, method of assembly, also affects the fire-test-response. For these reasons, evaluation of the variation is required for application to construction in the field.

UL 263

1.3 These requirements are intended to evaluate the length of time that the types of assemblies specified in 1.1 will contain a fire or retain their structural integrity, or both, dependent upon the type of assembly involved, during a predetermined test exposure. The test evaluates the assembly’s resistance to heat, and in some instances to a hose stream, while carrying an applied load, if the assembly is load bearing.

As both a contractor and home inspector, I hear the term firewall used by a lot of home inspectors when referring to that special wall which separates the garage from the home, or other walls. In some cases, this wall will separate complete living spaces from one another as in the case of some townhouses and apartments. 

If you’re in the California Residential Code (CRC) you’ll quickly find that the word firewall isn’t in the code book but only a couple times. That said, however, when we’re referring to the wall or door within a garage which separates the garage from the house, as contractors we refer to this as the fire separation wall or fire barriers and or course fire doors.

The word firewall denotes a “tested system”. A true firewall is usually designed, which is to say it’s a “designed system.” Moreover, its made-up from special materials all “rated” to resist a fires destructive powers for well, a predetermined amount of time such as for example 1-4 hours. All in order to prevent the spread of fire from one building to another building.

Firewalls are exterior wall systems which extend continuously from a building’s foundation all the way through the roof. The firewall is much more thick than other wall types and are specifically designed with a prescribed fire resistance duration. A firewall allows a building to be subdivided in the event the burning building becomes structurally unstable causing the burning section to break or fall away from other sections of the building.

How does the California Fire Code define Santa Clarita firewalls?

FIRE WALL. A fire-resistance-rated wall having protected openings, which restricts the spread of fire and extends continuously from the foundation to or through the roof, with sufficient structural stability under fire conditions to allow collapse of construction on either side without collapse of the wall.

How does the California Building Code define Santa Clarita firewalls?

[BF] FIRE WALL. A fire-resistance-rated wall having protected openings, which restricts the spread of fire and extends continuously from the foundation to or through the roof, with sufficient structural stability under fire conditions to allow collapse of construction on either side without collapse of the wall.

[BF] FIRE RESISTANCE. That property of materials or their assemblies that prevents or retards the passage of excessive heat, hot gases or flames under conditions of use.

[BF] FIRE PROTECTION RATING. The period of time that an opening protective will maintain the ability to confine a fire as determined by tests specified in Section 716. Ratings are stated in hours or minutes.

Fire separation | more common in the Residential code

Not like the tested fire rated assemblies found in multi-family dwelling units (condominiums, townhouses or duplexes etc.) or the firewall systems in commercial applications, single family residences are provided with a much more simple solution for fire separation.

Here in Santa Clarita, I see home inspectors mis-use the term firewall constantly. As a matter of fact, I can’t recall ever seeing a report which characterized the separation wall for what it truly is… a fire separation wall, not a fire resistance-rated assembly.

The standards for single family home’s separation wall between the garage and the living space is simple. In most cases, ½” drywall is all that’s needed to meet the santa clarita fire separation requirements. When there is a living space above a garage for example, the drywall size is thus increased to ⅝”.

Let’s see what the California Building Codes say about this…

California Fire Code AJ601.3 Separation walls.

Where the work area is in an attached dwelling unit, walls separating dwelling units that are not continuous from the foundation to the underside of the roof sheathing shall be constructed to provide a continuous fire separation using construction materials consistent with the existing wall or complying with the requirements for new structures. Performance of work shall be required only on the side of the wall of the dwelling unit that is part of the work area.

2016 California Residential Code R302.6 Dwelling/garage and/or carport fire separation.

The garage and/or carport shall be separated as required by Table R302.6. Openings in garage walls shall comply with Section R302.5. Attachment of gypsum board shall comply with Table R702.3.5. The wall separation provisions of Table R302.6 shall not apply to garage walls that are perpendicular to the adjacent dwelling unit wall. A separation is not required between the dwelling unit and a carport, provided the carport is entirely open on two or more sides and there are not enclosed areas above.

santa clarita firewall

2016 California Residential Code R302.9.1 Flame spread index.

Wall and ceiling finishes shall have a flame spread index of not greater than 200.

2016 California Residential Code R302.9.3 Testing.

Tests shall be made in accordance with ASTM E84 or UL 723.

Of course, there are other requirements which directly affect the fire separation.

Ductwork in fire separation walls.

Ducts which can be easily destroyed in a fire thus allowing heat to enter a building must maintain minimum material standard which is sheet metal no less than 26 gauge. Furthermore, ducts are not allowed to terminate into the garage.

2016 California Residential Code R302.5.2 Duct penetration.

Ducts in the garage and ducts penetrating the walls or ceilings separating the dwelling from the garage shall be constructed of a minimum No. 26 gage (0.48 mm) sheet steel or other approved material and shall not have openings into the garage.

Other penetrations.

The building code address annular spaces which are the result of pipes, conduit or ductwork which penetrates the fire separation wall. It’s important that the building official verify that these spaces are properly filled and do not compromise the protection offered by the common wall between the garage and the residence against free passage of smoke, fire, noxious gases and odors.

R302.5.3 Other penetrations.

Penetrations through the separation required in Section R302.6 shall be protected as required by Section R302.11, Item 4.

Section R302.11, Item 4.

At openings around vents, pipes, ducts, cables and wires at ceiling and floor level, with an approved material to resist the free passage of flame and products of combustion. The material filling this annular space shall not be required to meet the ASTM E136 requirements.

Townhomes are separate buildings

According to the current building code, the 2015 IBC defines a townhouse as “A single-family dwelling unit constructed in a group of three or more attached units in which each unit extends from foundation to roof and with a yard or public way on not less than two sides”.

Building Code Definitions

2016 California Residential Code R302.2 Townhouses.

[RB] TOWNHOUSE. A single-family dwelling unit constructed in a group of three or more attached units in which each unit extends from foundation to roof and with a yard or public way on not less than two sides.

Unlike single family homes, Townhouses are considered two separate buildings. What exactly does this mean? Well, in a single family house we have fire separation within the garage to living space connection. In Townhouses,  they (where connected) also have another requirement and that is fire separation between buildings from the foundation all the way to the underside of the roof.

2016 California Residential Code R302.2 Townhouses.

Common walls separating townhouses shall be assigned a fire-resistance rating in accordance with Section R302.2, Item 1 or 2. The common wall shared by two townhouses shall be constructed without plumbing or mechanical equipment, ducts or vents in the cavity of the common wall. The wall shall be rated for fire exposure from both sides and shall extend to and be tight against exterior walls and the underside of the roof sheathing.

1. Where a fire sprinkler system in accordance with Section R313 is provided, the common wall shall be not less than a 1-hour fire-resistance-rated wall assembly tested in accordance with ASTM E119 or UL 263.

2. Where a fire sprinkler system in accordance with Section R313 is not provided, the common wall shall be not less than a 2-hour fire-resistance-rated wall assembly tested in accordance with ASTM E119 or UL 263.

Code does not require a fire rated door in single family residences

In single family homes, a fire rated door or fire rated frame assemblies are not a requirement, thus the term “fire door” is not always accurate. To be clear, fire doors are minute and hourly rated assemblies.

Commercial doors are rated “hourly”
Hourly ratings
Steel fire doors are “rated” by time (in minutes or hours) that a door can withstand exposure to fire test conditions. Hourly ratings include 1-1/2-hours, 1-hour, 3/4-hour, and 1/3-hour, with the maximum rating required of any swinging type fire door being three hours.

Not only is the door rated to resist heat in commercial applications, but the frame, the glass and the hardware are all also part of the fire rated assembly.

2010 202 CBC [B] FIRE DOOR.The door component of a fire door assembly.

[B] FIRE DOOR ASSEMBLY. Any combination of a fire door, frame, hardware and other accessories that together provide a specific degree of fire protection to the opening.

[A] LABELED. Equipment, materials or products to which has been affixed a label, seal, symbol or other identifying mark of a nationally recognized testing laboratory, approved agency or other organization concerned with product evaluation that maintains periodic inspection of the production of the above-labeled items and whose labeling indicates either that the equipment, material or product meets identified standards or has been tested and found suitable for a specified purpose.

[BF] FIRE DOOR. The door component of a fire door assembly.

BF] FIRE DOOR ASSEMBLY. Any combination of a fire door, frame, hardware and other accessories that together provide a specific degree of fire protection to the opening.

Can’t go through a bedroom into the garage

santa Clarita fire-doorResidential Openings from the garage are permitted only into rooms that are not used for sleeping. These openings must be protected by the installation of a door comply with the provisions of section 302.5.1.

Many different types of additions and conversions are performed within a home to add bedrooms or a way to gain direct access into a garage. It is a change made to accommodate living arrangements for home owners or as a convenience to get into the garage without having to go outside.

Many of these alterations are performed without obtaining building permits. That is why it is our job to make the buyer aware that if this situation does exist in their potential purchase.

Did you know that a door leading from a garage directly into a bedroom is a violation of current building code? Openings from a private garage directly into a room used for sleeping purposes shall not be permitted.

From Los Angeles County BLS

“Separation of Private Garages. In the one-hour occupancy separation between Group R3 (dwelling) and Group U (garage) Occupancies, the separation may be limited to the installation of materials approved for one-hour fire-resistive construction on the garage side and a self-closing, tight fitting solid-wood door 1-3/8 inches in thickness, or a self-closing, tight fitting door having a fire-protection rating of not less than 20 minutes when tested in accordance with Part II of Uniform Building Code Standard 7-2. Under no circumstances shall a private garage have any opening into a room used for sleeping purposes.
California Building Code Definition [BF] SELF-CLOSING. As applied to a fire door or other opening protective, means equipped with an device that will ensure closing after having been opened.”

The most common situation which most of us are used to is the door between the garage and the inside of the home. Solid wood doors 1 ⅜” thick, solid or honeycomb steel doors and 20 minute fire rated doors are required for use in the opening between the garage and the dwelling unit.  

A self closing device must be installed on these doors as a safeguard to limit free flow of carbon monoxide or other products of combustion into the living area.

Santa Clarita Home Inspectors

R302.5.1 Opening protection.
Openings from a private garage directly into a room used for sleeping purposes shall not be permitted. Other openings between the garage and residence shall be equipped with solid wood doors not less than 13/8 inches (35 mm) in thickness, solid or honeycomb core steel doors not less than 13/8 inches (35 mm) thick, or 20-minute fire-rated doors, equipped with a self-closing and self-latching device

Although not a requirement for the doors leading from the garage into the residence, as contractors having worked in commercial construction with fire door assemblies, we always suggest the door and frame possess a tight seal or weatherstripped.

Since there is no mention in the 2016 CRC of glass installed in the door we assume it’s left up the AHJ to make the final call. They may require the glass to be fire rated, which is extremely likely.

(AHJ) AUTHORITY HAVING JURISDICTION-An organization, office or individual responsible for enforcing the requirements of a code or standard, or for approving equipment materials, an installation or procedure.NFPA 80 Definition AHJ

Many of us hate the self closing device on the door from the garage into the house. Were you aware that the NFPA does not allow “hold open” features like the door kickdowns”?

NFPA The closing mechanism shall not have a hold-open feature.

The NFPA even goes as far as mandating the full and complete latching for the door.

NFPA Self closing doors shall swing easily and freely and shall be equipped with a closing device to cause the door to close and latch each time it is opened.

Other doors into the fire separation wall

firedoor santa clarita
Santa Clarita home inspectors

Many of us have seen those little doors in the ceiling or within our attics in our homes from time to time. But did you know that these doors also have to possess a fire rating? Most all AHJ’s require the door to be rated and in some cases up to 3 hours, depending on your location and requirements of the Building department having jurisdiction. These doors are easily purchased and installed, actually, I personally find them much easier to install than a traditional passage door and frame.

MAZZA Inspection Group Santa Clarita

The Mazza Inspection and Testing group of Santa Clarita is a professional, inspection and testing company operating with Los Angeles.  As a testing only company we offer many different testing services such as;

Visit our website to find out more about us and what we offer as well as pricing solutions for your specific project.

Marc Mazza of Mazza Inspection Company is a  Water intrusion specialist. 

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Comments 3

  1. Thank you for this article about fire separation and fire walls. You implied that fire separation solutions are much more simple in residential settings than commercial ones. I’m kind of interested to learn if commercial buildings would need to utilize more materials or if it depends what kind of fuel is onsite.

    1. Hey Taylor, the NFPA is a great resource for more information regarding specific materials used in commercial fire separation. Cant really compare the separation requirements of commercial to residential separation standards. Looking at the CBC I’m guessing the groups H and S might require specific levels of fire separation but as you know (I’m sure), the primary differences in these walls is their construction i.e. the hour rating or / and listing. Penetrations into these walls is based around the rating of that wall.

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