California building codes for fireplaces have their basis in the guidelines established by the International Code Council, or ICC. The ICC develops safety and fire prevention codes and standards applied in residential and commercial buildings. Check with your local building code department to find out what the specific rules are for installing fireplaces in your area.
In California, property owners or contractors usually must obtain a permit from the local building department before the installation of a masonry or wood burning pre-fabricated fireplace. Some codes allow the installation of certain gas-burning decorative fireplaces without a permit. Check with your build code department because the regulation may require a permit to install the gas line. Each permit must have specific information regarding the scope of the proposed work.
Some municipalities require builders/owners to submit plans of their projects before approving applications for permits. The plans should include the specifications for the type of fireplace. Installation using pre-fabricated fireplaces tested and approved by specific agencies, such as the International Conference of Building Officials or masonry fireplace specifications that meet the predetermined codes of municipalities, may speed up the permit approval process. Custom-built fireplace plans must have an architect or engineer stamp and calculations and go through the plan review process.
Fireplace hearths, which make up the floor area in front of the fire, must extend at least 20 inches from the front of the firebox into the room and must be 4 inches thick. Acceptable materials include brick, stone or concrete. Some people use marble, slate, terrazzo or quarry tile. Some localities may have additional requirements for the side extension of the hearth.
ICC code requires masonry fireplaces to have a 12-inch thick foundation that extends 6 inches to the front and sides of the chimney and wall. The back and side walls of masonry fireboxes have to be at least 10 inches thick. Builders may use stone, concrete or grouted hollow blocks. Another option consists of using 8-inch thick material and 2-inch firebricks. Rules call for 2 inches of clearance on the sides from combustible materials, such as studs, joists or beams, and 4 inches from the back of the firebox. Builders must install 1-inch-thick fire blocks where the fireplace passes through walls or ceilings. Codes require a minimum of 6 inches from the top of the firebox opening to the trim and mantel.
Prefabricated fireplaces consist of factory made units with metal shells. California allows direct vent, B-vent, and chimney vented fireplaces. Direct vent and B-vent refers to methods of venting using metal pipes through a sidewall or up and through the roof. Most municipalities do not allow vent- free fireplaces because of the concern for carbon monoxide exposure and oxygen depletion from the space. Follow the manufacturers' instructions and local building codes for installing these products.
Generally, masonry and prefabricated fireplaces have similar requirements for chimneys. Masonry or factory-built metal chimneys must meet the local code requirements.The chimney must terminate 3 feet above the roof. The chimney must end at least 2 feet above any portion of the structure that comes within 10 feet of the chimney. For pre-fabricated chimneys, check the manufacturer's guidelines. Often, municipalities require masonry chimneys to have a fired-clay lining for chimneys made of 4-inch brick.
Check the local codes and product specifications for the correct size of the flue, which varies depending on whether you use round or rectangular flues. A fireplace must have its own flue. Chimney located on the interior must have a two-inch clearance from combustible materials. The regulation requires a one-inch clearance for chimneys located entirely on the exterior.