Over the years I’ve built hundreds of fireplace mantels. I’m often asked:
What is the typical and safest distance between the mantle piece and fireplace?
RULE OF THUMB (considering the mantel is wooden)
The most common measurement is to place it 12″ above the top of the fireplace system, and for every additional inch that the shelf protrudes out, add an additional inch. So when using this method, I would start out with 3/4″ lumber (common sized wood = 3/4″ thick) and keep the wood on the sides and top at least 12″ away from the firebox (opening of the fireplace). Then for every one inch distance away from the box, add an inch to the depth. Example: a 6″ protrusion would be 18″ above the opening. Two common distances that I’ve worked with are to place the top of the mantel about 55 to 65 inches above the floor and try to finish with a mantel shelf depth of 8 – 12 inches. Use your own personal tastes as there is no exact number. (always contact a licensed and insured professional to design and build your mantel and fireplace trim)
2009 IRC BUILDING CODE (check with your local and state building department)
Exposed combustible mantels or trim may be placed directly on the masonry fireplace front surrounding the fireplace opening providing such combustible materials are not placed within 6 inches (152 mm) of a fireplace opening. Combustible material within 12 inches (306 mm) of the fireplace opening shall not project more than 1/8 inch (3 mm) for each 1-inch (25 mm) distance from such an opening. (Source Code)
Stockings Were Hung With Care
Keep Christmas time safe. Use good judgement and don’t hang Christmas stockings directly in front of the firebox. To lower the opportunity of unsafe conditions (considering you have a pre-fab unit) consider keeping the wire mesh pulled shut while you have the fireplace working. On wood burning fireplaces the wire mesh will protect you from hot embers falling out of the firebox.
DO NOT place your Christmas Tree near your fireplace, whether the fireplace is pre-fab or job built. Dry pine needles are perfect kindling and will easily catch fire. Also, never ever ever cut up your tree and burn it in the fireplace.
— Gary Smith (@MSHomeInspector) December 24, 2013