- Always check local codes as those will trump these recommendations.
- Do NOT install a home standby generator under a wooden deck or platform.
- Units that do not feature the SwRI logo must be installed 5 ft. from combustible materials and 3 ft. from non-combustible materials.
Home Standby Generator Clearance Requirements
Clearance requirements ensure the generator is operated at a safe distance where heat and fumes will not cause fires or health hazards. The exhaust gets extremely hot and remains hot after shutdown. Flammable material may ignite and burn from the heat of the exhaust system.
NFPA 37 Overview
- The National Fire Protection Association’s standard for the installation and use of stationary generators.
- Its requirements limit the spacing of the generator from a structure or wall.
- The unit must be located where it’s readily accessible for maintenance, repair, and first responders.
- Minimum clearance requirements are for adequate airflow, maintenance, and safety.
NFPA 37 Requirements
For a complete and updated list, see the NFPA 37 web page.
- 5ft. from openings in walls (operable windows, doors, vents, window wells, or openings in the wall).
- 18 in. of clearance from the back of the generator to a stationary wall or building (based on testing done by the Southwest Research Institute or SwRI).
- 5 ft. of clearance above the generator.
- 3 ft. of clearance at the front and both ends. This includes trees, shrubs, and bushes. Vegetation not in compliance could obstruct airflow and exhaust fumes could inhibit plant growth.
- In addition to these requirements, verify all potential for water intrusion is directed away from the generator enclosure: sprinklers, roof run-off, down spouts, and sump pump discharge.
Site selection and preparation
Potential CO entry points
Generator exhaust can enter a structure through large openings, such as windows and doors. However, exhaust and CO can also seep into the structure through smaller, less obvious openings.
Protect the structure
Verify the structure itself as correctly caulked and sealed to prevent air from leaking in or out. Voids, cracks, or openings around windows, doors, soffits, pipes, and vents can allow exhaust gas to be drawn into the structure. Some examples of entry points are described and included in, but not limited to, the accompanying table.
What about other requirements and codes?
Codes vary by region - Contact your local building inspection department. This department can usually be contacted through your local city government web site.
Permitting varies by region - This includes the time frame to receive a permit, what permits must be pulled, and the costs of the permits. See What factors influence the cost of installing a home standby system? Plumbing and electrical - Generator installation involves plumbing and electrical work. This should be performed by experienced professionals. We recommend contacting a local certified dealer: How Can I Find a Generac Service Dealer in My Area? Further information, such as the distance from the gas meter, can be found in the installation manuals. See the How Do I Find a Copy of My Home Standby Generator Owner's Manual, Spec Sheets, or Installation Manual? article for more information. Note that local codes should always be followed. 
