Cal-133 FAQ

Questions & Answers

A Fire Test for Seating Furniture in Public Buildings
State Department of Consumer Affairs, Bureau of Home Furnishings and Thermal Insulation


Q. What is California Technical Bulletin 133 (TB 133)?

A. TB 133 is a full-scale fire test for furniture manufactured for use in certain public buildings.

Q. Why was TB 133 developed?

A. TB 133 was developed by the bureau for two reasons.

In 1972 the California legislature enacted law requiring all upholstered furniture sold in California to be fire retardant. The Bureau of Home Furnishings was assigned the responsibility of developing fire standards. The bureau first addressed the fire safety of furniture in the residential occupancy by publishing Technical Bulletins 116 and 117, which became law in California in 1975, and are the minimum standards for any occupancy in California. It was not the bureau’s intent that TB 116 and TB 117 be the prescribed standards for public buildings. Therefore, TB 133 was developed to address the specific fire problems of furnishings in public buildings.

Second, after the issuance of TB 116 and TB 117, the bureau received many requests from fire departments, interior designers, architects and others asking for a fire performance standard for public building furniture. TB 133 was initially published in May 1984 as a document to be used by local fire authorities and others in buildings where they saw the need for such a standard.

Q. What is meant by a “full-scale fire test?”

A. TB 133 tests an actual article of furniture, or a furniture “mockup,” which includes all of the essential features of the finished furniture. A finished piece of furniture is placed in a test room and ignited by a gas ignition burner. Various measurements of temperature, smoke, carbon monoxide, heat generation, and weight loss of the furniture are taken. The measurements are then compared with test criteria developed by the bureau, which define acceptable fire performance. The standards does not specify how an article of furniture should be built, but only how the furniture should perform when tested by the procedure specified in TB 133. Therefore, TB 133 is known as a full-scale fire performance test.

Q. In the above answer a furniture “mock-up” is mentioned. What is a “mock-up?”

A. TB 133 permits testing of finished articles of furniture, or furniture “mock-ups.” Appendix D in TB 133 describes in detail the construction of a furniture “mock-up” system. Manufacturers interested in the “mock-up” approach to testing should carefully review this section of TB 133.

Q. What type of components comply with TB 133?

A. TB 133 is a full-scale fire performance test of complete articles of seating furniture, or furniture “mock-ups.” Therefore, there are no furniture components which by themselves comply with the requirements of TB 133. Only composite assemblies can be tested.

Q. Is TB 133 just “one more fire retardancy test?”

A. No. TB 133 does not call for tests of small samples of component materials. It requires that a complete seating furniture product be exposed to a large open flame in a specially designed test room. It then measures what happens when the components are used together.

Q. If I have other questions who should I contact at the bureau?

A. For questions regarding testing, contact Dr. Said Nurbakhsh. Questions regarding bureau policy or the implementation of TB 133 can be directed to the bureau chief, Gordon Damant. Both may be reached at (916) 920-6951 or FAX (916)488-7623.


Q. What is measured in the TB 133 test?

A. The test measures the amount of heat generated and the rate at which it is generated. In addition smoke opacity, carbon monoxide generation, and temperature are measured in the test room, as well as the weight loss of the product being tested. Test criteria have been developed which set limits on each of the measurements listed above.

Q. How can I find out more details about TB 133?

A. A copy of TB 133 is available at no cost from the bureau. In addition, the bureau has a Flammability Information Package available which contains a copy of all of the bureau’s fire test standards.

Q. What is the procedure for a manufacturer or supplier to have a product evaluated by the bureau?

A. If you would like to have products tested by the bureau, you should contact the bureau’s fire test engineer, Dr. Said Nurbakhsh. He will be able to provide all the information and test documentation that you need prior to testing. You will need to follow the following procedure:

1. Fill out a product description form for each product you wish to have tested;

2. Agree, in writing, to pay for the testing cost by either pre-paying or providing a purchase order number;

3. Indicate if you want a video tape of the test – there is a small additional cost; and

4. State if you would like to be present at the bureau’s test facility for the testing.

Q. Are there other test laboratories available that can perform the TB 133 test?

A. Yes. The bureau can provide a list of laboratories that are known to have the capability of testing in accordance with TB 133. Please contact Dr. Nurbakhsh.

Q. My fire test room is a little smaller than the room used by the bureau. Can I use it for TB 133 testing?

A. TB 133 permits rooms of different sizes to be used for testing, if it can be shown that equivalent test results can be obtained. Tests by the bureau, and others, have shown that other available test rooms, such as the ASTM test room, do provide equivalent test results. In addition, TB 133 also permits testing using a full-size furniture calorimeter.


Q. What kind of buildings is TB 133 intended for?

A. TB 133 is a standard for public buildings or public assembly areas. The specific types of public buildings might vary from state to state, depending upon local regulations. However, in California, TB 133 will apply to prisons and jails, hospitals, healthcare facilities, board and care homes, old age convalescent homes, licensed child care facilities, stadiums, auditoriums, and public assembly areas of hotels and motels.

Q. What is a public assembly area in a hotel or motel?

A. For the purposes of TB 133, a public assembly area is considered to be any area in the hotel or motel containing ten (10) or more articles of seating furniture.

Q. Does TB 133 apply to hotel and motel guest rooms in California?

A. No. Only to public assembly areas of hotels and motels as described above.

Q. Does TB 133 apply to one and two family homes?

A. No! In California all furniture sold in the state must comply with the requirements of Technical Bulletin 117. This is the minimum standard for all furniture sold in the state, including furniture intended to be used in the home. TB 133, on the other hand, is a special standard for public buildings.

Q. Is TB 133 applicable only to public areas accommodating 50 or more people?

A. Many states are adopting TB 133 as a seating standard for public buildings, but the specific types of buildings and the definition of public buildings may vary from state to state. The legislation, which has been enacted by several states, requires the local state fire marshal’s office to develop regulations which would implement TB 133 for those states. Although TB 133 is the referenced test procedure in the states that have adopted it, it is only a test procedure. The method by which it will be implemented and enforced by each state will be decided by local authorities. For example, California will require TB 133 compliance in facilities such as jails, penal institutions, hospitals, healthcare facilities, old age convalescent homes, stadiums, auditoriums, licensed child care facilities, and public assembly areas of hotels and motels. The definition of a public assembly area of a hotel and motel is any location containing ten or more articles of seating furniture. Therefore, under California requirements there is no restriction to buildings with 50 or more occupants. In addition, some local fire authorities may be more restrictive than the bureau’s requirements for particular buildings in their area of jurisdiction.

Q. Is TB 133 required in sprinklered buildings?

A. In California, TB 133 is voluntary or discretionary in any facility which is fully sprinklered in accordance with NFPA 13-1987 or UBC Standard No.38-I, 1988. In this type of facility a manufacturer may choose to comply with TB 133, but it would not be a mandatory requirement. However, in California, even in sprinklered facilities, seating furniture must comply with California TB 117, which is the minimum standard in the state.

In other states, where TB 117 does not exist, granting an exemption for sprinklered buildings will be more difficult since those states have no alternative standard, such as TB 117.

Also, before deciding not to comply with TB 133 in sprinklered buildings, manufacturers and others may wish to contact their attorney. The fact that a building is sprinklered may not relieve them from liability in a products liability lawsuit


Q. Does TB 133 only apply to furniture sold in California?

A. The bureau’s jurisdiction applies only to the state of California. However, several other states have adopted TB 133, and others are expected to follow.

Q. How will TB 133 be enforced in other states?

A. All of the states that have adopted TB 133, other than California, have designated the state fire marshal as the person responsible for developing regulations and enforcing the standard. Questions regarding regulations and enforcement in those states should be directed to the Office of the State Fire Marshal.


Q. How can a furniture manufacturer comply with TB 133?

A. There are two basic methods of compliance with TB 133. One method is to find a compatible selection of components, which, when assembled, work well together under the test conditions of TB 133. Since TB 133 is a fire-performance test of finished furniture, or furniture “mock-ups,” no components can claim to be in compliance, nor are there any recommended components or material specifications. Since TB 133 is based solely on fire performance, a furniture manufacturer is permitted to make furniture in any manner he or she wishes, provided that the furniture complies with the test criteria of TB 133. The second basic method of compliance would be by use of an interliner or fire-blocking layer. There are a number of excellent materials available for this purpose. There may be advantages and disadvantages in using this approach. Depending upon the type of blocking layer selected, a double upholstery process may be required and a fire-resistant thread will be needed to sew cushions, etc. together. However, the use of a fire blocker may facilitate significant exchangeability to cover fabrics without the need for retesting. Where blocking layers are not used, fire performance may be drastically affected by generic changes in cover fabrics and other furniture components. In addition, the use of fire blockers may result in other trade-offs. For example, highly fire-retardant, and more expensive, cushioning materials may not be required. Also, fire-retardant treatments of cover fabrics may be unnecessary where appropriate fire blockers are used.

Q. TB 133 tests only the seat surface of furniture, therefore, should a manufacturer only protect the inside surfaces of the furniture, or should he be concerned with the outside furniture surfaces also?

A. The bureau’s intent in developing TB 133 is that furniture complying with the test be safer furniture. It is not the bureau’s wish that manufacturers seek to compromise the intent of the standard or attempt to “beat the test.” In designing a fire test such as TB 133, it is clearly not possible to use multiple ignition sources and multiple ignition locations on products. The intent of TB 133 is that furniture be manufactured to perform in a fire-safe manner irrespective of the point of ignition of the furniture. Therefore, manufacturers should produce furniture with the intent of making it safer furniture.

Q. How are products, such as sleeper sofas, handled under TB 133? Is the mattress tested separately?

A. TB 133 is a test of a finished product, or “mock-up.” Therefore the test is performed on a sleeper sofa as a finished product, which is the combined unit. However, federal law also requires all mattresses to comply with the federal mattress cigarette standard, 16 CER 1632 (DOC FF 4-72).

Q. If a manufacturer tests a chair, for example, with certain components, is it safe to assume that the same components would perform similarly in other types of style products?

A. This is a question which addresses classification of products. It is important to remember that TB 133 is a fire-performance test of a finished product, or “mock-up,” and the way the product performs in the test is the only criteria that concerns the bureau. The bureau’s TB 133 regulations do not specify the amount or type of testing that manufacturers should conduct.

In fact, the bureau’s regulations specifically state that testing is at the discretion of the manufacturer. It is not the bureau’s intent that a manufacturer test one of every product made. Classification of furniture is certainly possible. For example, it may be possible for a manufacturer, who makes 100 different products, to classify those products into groups which could be represented by, for example, 5-10 TB 133 tests. The classification should address worse case conditions, and should be based upon the styles of furniture made, the kinds of upholstery fabrics used, and whether or not fire blockers are used. The bureau is willing to give assistance and suggestions in the classification process, however, it is an issue that is too broad and comprehensive to cover in this booklet.

Q. Are there any secrets for complying with TB 133?

A. There are no secrets for compliance. All manufacturers have access to the same materials, which are made by a relatively small number of vendors. The bureau alone has tested products from more than 100 furniture manufacturers that are in compliance with TB 133. In addition, the bureau can provide a list of names and addresses of material suppliers whose products may be useful in complying with TB 133, when used along with other compatible components.

Q. What about the wood in furniture? Does it need to be fire resistant also?

A. Although wood is a flammable material, it is much less flammable than most fabrics and cushioning materials. It is not usually necessary to treat wood used in furniture, because vigorous burning of wood usually indicates that the furniture has already failed the test due to combustion of the fabrics and cushioning materials.

Q. Can plastics, which are used as part of the furniture structure, affect the TB 133 test?

A. Yes, structural plastics can create considerable problems in the TB 133 test, depending on the generic type of plastic used and the location of the plastic on the furniture. It is important for manufacturers to not only address flammability issues relating to fabrics and cushioning materials, but also other component materials, such as structural plastics. These materials may melt and drip during the test, creating a pool of burning molten plastic which may be an added ignition source for the furniture.


Q. It has been reported that certain fabrics do not perform well in the TB 133 test, and that some cushioning materials are better than others. How does a manufacturer find out what works and what doesn’t?

A. This is a question without an easy or short answer. Here are some general concepts. It is unlikely that furniture containing conventional California TB 117 polyurethane foam, or equivalent type products, will comply with TB 133 without the use of a fire blocker. Also certain types of fabrics such as polypropylene (or olefin) and vinyl (or PVC), are unlikely to perform well without the use of fire blockers. In addition, the bureau has encountered antagonistic reactions between materials, which are not fully understood, when manufacturers choose not to use fire blockers, but use a component approach to compliance with TB 133. However, in questionable areas the use of appropriate fire blockers will allow a wide selection of component materials to be used.

Q. How will a vinylized fabric, such as PVC, perform in the TB 133 test?

A. The bureau has found that typical vinyl type fabrics may create difficulties in the TB 133 test. Often there appears to be antagonism between some types of PVC fabrics and typical cushioning materials, which cause the smoke and carbon monoxide levels to exceed the test criteria. This can often be resolved by use of fire-blocking layers. These may be separate blockers which are placed between the PVC fabric and the cushioning materials, or the fire blocker may be incorporated into the design of the vinyl fabric. In the latter case, a separate fire blocker would not be necessary.

Q. A fabric supplier has indicated he has a TB 133 approved fabric. If I use this fabric will my furniture comply with TB 133?

A. No! There are NO furniture components of any kind that comply with TB 133. As indicated above, TB 133 tests furniture and not components. Therefore, there are no TB 133 approved fabrics.

Q. Although I manufacture contract furniture, most of the fabrics I use are provided by interior designers (COM fabrics). How will this affect testing and compliance with TB 133?

A. It is important to remember that the responsibility for compliance with Th 133 rests with the furniture manufacturer. Therefore, manufacturers should be certain that all components used in making furniture are compatible, with respect to TB 133. The use of highly flammable fabric on furniture may significantly affect the way the furniture performs in the TB 133 test. If you receive a lot of COM fabrics, you have little or no control over many of the fabrics you use; you should look carefully at the various fire-blocking materials available. The use of a high-quality fire blocker will allow a broad spectrum of upholstery fabrics to be used without significantly affecting the TB 133 test results.


Q. If decide to use some type of fire-blocking layer, are there any special precautions that I should take?

A. First, it is important to understand the concept of using a fire blocker. A fire blocker is used to create a fire barrier and to protect the furniture cushioning materials, which are often the major fuel source in furnishings, from the ignition source. Fire blocker materials are made from materials that are highly resistant to ignition. If the fire blocker is to perform properly, it is important that the integrity of the fire blocker be maintained at all times. If a manufacturer intends to sew the fire blocker into the furniture construction, it is critical that a tire-resistant sewing thread be used. Clearly it makes no sense to use a highly fire-resistant blocker with a conventional combustible sewing thread, which would quickly ignite and thus compromise the physical integrity of the blocking layer. Suppliers of fire blockers can recommend appropriate methods of application for their particular product

Second, it is a wise construction practice to cover all flammable cushioning surfaces with the fire blocker. Because the TB 133 test ignites furniture on the seat surface, there is a tendency by some manufacturers to use the fire blocker only on the interior surfaces of the furniture. Numerous bureau tests have shown this is not a wise practice. Many test failures have been caused by ignited fabrics burning into unprotected areas of furniture, thus causing a failure of the total system.

Q. Are there different types of fire-blocking layers?

A. Yes, there are several kinds of fire blockers available. Some are relatively simple products consisting of fiberglass yarn; others are made from highly fire-resistive fibers; some consist of a combination of materials; and others are highly-engineered products. A manufacturer should choose the fire blocker which works best for his or her manufacturing process.

Q. Will fire blockers work with all types of furniture?

A. Fire blockers can probably be made to work with almost any style of upholstered furniture. However, it is important to remember that the effectiveness of fire blockers may be compromised if the physical integrity of the fire blocker is violated. Therefore, it is not usually advisable to use fire blockers in furniture intended for use in occupancies where there is a known high incidence of vandalism. This may be typical of jails, prisons, mental health facilities, and public transport, for example. In addition, authorities in such facilities should periodically check furnishings for evidence of vandalism which may result in a compromise of fire-safety features built into products.


Q. Does TB 133 require furniture to be labeled?

A. The bureau’s regulations require a flammability label to be attached to each article of furniture stating the following:



Q. How large should the label be? And are there any other requirements?

A. The minimum label size is 2 x 3 inches. In addition, the regulation requires all lettering in capitals, no less than one-eighth inch in height.

Q. Should I be aware of any other labeling requirements?

A. Every article of upholstered furniture sold in California is required to have a “law label” attached. This is the label which shows a generic description of the concealed filling materials in the product and lists them in percentage by weight. The label also shows the assigned Registry Number of the manufacturer. The bureau has a separate booklet available which provides information regarding the “law label” requirements and shows approved “law label” formats.

Q. How may I obtain a Registry Number?

A. It is a requirement of California law that every manufacturer of upholstered furniture selling in the state, hold a valid, unexpired furniture manufacturer’s license with the bureau. As part of the licensing process, a Registry Number is issued by the bureau, which uniquely identifies the manufacturer. Once the license is issued, it must be renewed every two years. The license is required for the manufacture and sale of any type of upholstered furniture in California and covers residential, office, and contract furniture.


Q. How much will TB 133 add to the cost of furniture?

A. That is a difficult question to answer because there are many styles of furniture and a number of possible ways of complying. Manufacturers with little, or no, experience with TB 133 sometimes quote cost premiums of 30-40 percent. However, knowledgeable manufacturers who have developed creative ways of making furniture less flammable, and who are familiar with fire-blocking materials and other fire-retardant products, can produce TB 133-complying furniture for 5 percent or less, depending on style and other factors.