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Outdoor Chemical Storage Buildings

Quick Tips #257

Chemical Storage BuildingSafely storing hazardous materials and wastes is a common problem for many companies. Outdoor Chemical Storage Buildings provide an effective solution to the problem. The National Fire Protection Association (NFPA) defines an outdoor chemical storage building as: "a prefabricated structure, manufactured primarily at a site other than the final location of the structure, and transported completely assembled or in a ready-to-assemble package to the final location." These buildings provide an economical means of storage and secondary containment because they eliminate the expense of constructing permanent structures.

A number of things need to be considered when selecting appropriate outdoor chemical storage buildings. Your choice will depend on the type of materials to be stored, the location of the building and design requirements.

Type of Material to Be Stored

If the materials to be stored are either flammable or combustible, you will need a building that meets the NFPA Code 30, Uniform Fire Code (UFC) Articles 79 and 80, or an equivalent local code. Check with your local Fire Marshall to determine which code is locally enforced.

The class of the flammable-combustible material (refer to NFPA Code 30) can also determine what type of building construction is required. Highly flammable materials, such as Category 1, 2, or 3 liquids, will require either a Non–Combustible building or a Fire-Rated building. Non–Combustible buildings are constructed of non-combustible material (such as steel), whereas a Fire-Rated building are constructed of non-combustible materials and include fire resistant insulation in the walls. Fire–Rated buildings are further divided into categories based on the fire resistance of the walls, roof, and openings (doors and vents).

When storing liquids that are not considered a flammable (such as corrosives or toxics), a Non–Combustible building should be sufficient.

Storage vs. Dispensing

The design of the building will also be affected by whether or not you will be dispensing from containers stored in the building. If you will be dispensing a Category 1, 2, or 3 liquid within the building, additional design features such as explosionproof wiring, explosion-relief panels and a ventilation system may be required.

Amount of Material to Be Stored

The interior size of the building should accommodate the number of containers required in a single layer and an adequate sump capacity to comply with the Environmental Protection Agency (EPA) Secondary Containment Requirements (40 CFR 264). To meet this regulation, the sum containment should be large enough to hold 100% of the volume of the largest container stored in the building or 10% of the total volume of all containers stored in the building, whichever is larger.


The type of building you select will also have a bearing on the chosen location. Factory Mutual (FM), an insurance and testing agency, specifies minimum distances between the storage building and any other main (occupied) building on the site and the property line of the facility. The following distances are specified by FM:

Type of Building Distance from Main Building or Property Line
4 hour fire rated: (Walls rated for 4 hours, roof and opening rated for 3 hours) < or =10 ft.
2 hour fire rated: (Walls rated for 2 hours, roof rated for 1 hour, and openings rated for 1-1/2 hours) 10-50 ft.
1 hour fire rated: (Walls rated for 1 hour, roof rated for 1 hour, and openings rated for 3/4 hour) 50-75 ft.
Non-combustible: (No fire rating) >75 ft.

Compliance and Approvals

As mentioned earlier, construction of outdoor chemical storage buildings must comply with a number of regulations including EPA 40 CFR, OSHA 29 CFR 1910, NFPA Codes 30 and 70, and UFC Article 79 and 80. In addition to the construction requirements, certain approvals may also be required for these buildings. These approvals include UL (Underwriters Laboratories) Classification and FM Approval.

Additionally, certain states require that a Professional Engineer apply a Seal of Approval to the building, indicating that it meets all state regulations. Please contact your local Fire Marshall or the agency in your jurisdiction for more details on this State Seal Program and to confirm if your state requires this approval seal.


A variety of options are often available for outdoor chemical storage buildings, helping you to meet all regulatory codes, or to simply customize the building to your needs. Available options include electrical service, heating and cooling systems, fire suppression systems, shelving, insulation, and explosion-resistant features.

More Assistance

If you have further questions regarding outdoor chemical storage buildings or if you would like help selecting and designing a building to meet your needs, please feel free to contact for all technical inquiries about our Outdoor Chemical Storage Buildings, please contact your local Grainger branch.

Commonly Asked Questions
Q.   Can outdoor chemical storage buildings be moved from one location to another?
A.   Yes. Outdoor chemical storage buildings are designed to be portable. When moving a building to a new location, be sure to confirm that the new location meets all required distances and local codes. A building can also be moved indoors if needed. Buildings being relocated indoors should have a continuous ventilation system that is exhausted to the outdoors, a 4-Hour fire rating, a fire suppression system, and explosion relief panels directed towards a safe exterior location. Again, be sure to consult your local Fire Marshall to insure compliance with all local and/or state codes.


29 CFR 1910.106 Flammable Liquids

40 CFR 264 Standards for Owners and Operators of Hazardous Waste Treatment, Storage and Disposal Facilities

National Fire Protection Association Code 30 Flammables and Combustible Liquid Codes

National Fire Protection Association
Quincy, MA

Factory Mutual
Norwood, MA

(Rev. 2/2013)

Find even more information you can use to help make informed decisions about the regulatory issues you face in your workplace every day. View all Quick Tips Technical Resources at

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Please Note:
The content in this newsletter is intended for general information purposes only. This publication is not a substitute for review of the applicable government regulations and standards, and should not be construed as legal advice or opinion. Readers with specific compliance questions should refer to the cited regulation or consult with an attorney.

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