Low to Moderate (Not recommended for novices due to critical fire safety and structural requirements; professional masonry and code compliance experience is often essential for safety and longevity.)
A fireplace hearth rebuild involves critical fire-safety elements, structural integrity of masonry, and adherence to specific clearance and material requirements per the IRC, requiring skilled execution to ensure occupant safety and code compliance. It is not considered simple due to these inherent risks.
Project Guidelines & Rules
Permitting & Administration
3 Rules
Obtain necessary permits from your local building department prior to commencement of any work involving structural alterations or changes to fire-rated assemblies.
2024 IRC R105.1 (Permits required)
Submit detailed plans or specifications, including proposed materials and construction methods, to your local building department for review and approval.
2024 IRC R106.1 (Submittal documents)
Schedule and pass required inspections by your local building department at specified project stages (e.g., rough-in, final masonry, final inspection) to verify compliance.
2024 IRC R109.1 (Inspections)
Hearth Construction Requirements
6 Rules
Hearth extensions shall be supported by structural elements capable of safely carrying the imposed load, independent of the firebox structure, unless otherwise specifically engineered.
2024 IRC R1001.10 (Hearth extension material and support)
For fireplaces with an opening 6 square feet or larger, the hearth extension shall project at least 20 inches in front of and at least 12 inches beyond each side of the fireplace opening.
2024 IRC R1001.12.1 (Hearth extension dimensions)
For fireplaces with an opening less than 6 square feet, the hearth extension shall project at least 16 inches in front of and at least 8 inches beyond each side of the fireplace opening.
2024 IRC R1001.12.1 (Hearth extension dimensions)
Hearth extensions shall be constructed of noncombustible material, such as brick, concrete, stone, or tile, with a minimum thickness of 4 inches.
2024 IRC R1001.10 (Hearth extension material and support)
The top surface of the hearth extension shall be level with the bottom of the firebox opening.
2024 IRC R1001.12.2 (Hearth extension level)
Any combustible forms or temporary supports used during the construction of hearth extensions shall be completely removed upon project completion.
2024 IRC R1001.10 (Hearth extension material and support)
Firebox, Lintels & Clearance Considerations
5 Rules
Inspect the firebox for integrity. Any cracks or damage to firebrick or refractory mortar must be repaired or replaced with approved materials to prevent heat transfer to combustible construction.
2024 IRC R1001.3 (Firebox lining)
Ensure the fireplace opening has a minimum effective area of the flue not less than 1/12 the area of the fireplace opening, or as specified by engineered design.
2024 IRC R1001.6 (Fireplace opening dimensions)
Verify and maintain required clearances to combustible materials around the firebox, ensuring no combustible components are within the specified critical distances (e.g., 10 inches from the back and sides of masonry fireboxes to combustibles).
2024 IRC R1001.14 (Combustible material clearance)
Combustible mantels or other trim shall not be placed within 12 inches of the fireplace opening. Combustible materials located within 18 inches of the opening shall not project more than 1/8 inch for each 1 inch distance from the opening.
2024 IRC R1001.15 (Combustible trim and mantels)
All steel lintels or supports over fireplace openings shall be minimum 3/16 inch thick steel, with a minimum bearing length of 4 inches at each end.
2024 IRC R1001.9 (Lintel support)
Material Standards & DuPage County Climate
2 Rules
All masonry units, firebrick, and refractory mortar used in the construction of the firebox and hearth shall be approved materials and meet appropriate ASTM standards for their intended use.
2024 IRC R1001.3 (Firebox lining); 2024 IRC R1001.10 (Hearth extension material)
For any exterior fireplace components, foundations supporting hearths or associated structures must extend below the 42-inch frost depth or be designed as frost-protected shallow foundations in accordance with accepted engineering principles, to account for DuPage County's climate.
2024 IRC R403.1.4 (Frost Protection)
Electrical & Gas Appliances
3 Rules
Any electrical components associated with gas logs, blowers, or lighting must be installed by a licensed electrician in accordance with the 2023 NEC.
2023 NEC 110.3(B) (Installation and Use)
Electrical wiring or devices in close proximity to the fireplace shall maintain required clearances from heat sources and comply with NEC requirements for temperature limitations of conductors and devices.
2023 NEC 110.12 (Mechanical Execution of Work); 2023 NEC 310.14 (Conductors in General)
Gas piping for existing or new gas log inserts must comply with the 2018 International Fuel Gas Code (IFGC) and be inspected for leaks and proper operation by a qualified professional.
2018 IFGC 406.1 (General); 2018 IFGC 406.4 (Test pressure)
Plumbing Code Applicability
1 Rules
The Illinois Plumbing Code is generally not directly applicable to a fireplace hearth rebuild unless the project involves the relocation or modification of water supply, drainage, or venting systems which intersect or are integrated with the fireplace structure.
Illinois Plumbing Code Section 890.100 (Scope and applicability)
