Mantel Clearance for Masonry Versus Manufactured Fireplaces

For site-built fireplaces you need to check local codes, but for manufactured units you follow the UL specs. August 28, 2010

Question
I am re-surfacing a fireplace and adding a solid wood mantel but keep finding conflicting information on mantel clearance. The mantel projects 9" off the wall and I have received height requirements that range from 9" to 19" to even 32" above the firebox for placement. Any advice would be appreciated as the client wants the job completed as soon as possible.

Forum Responses
(Architectural Woodworking Forum)
From Gary Katz, forum technical advisor:
Most of Los Angeles county is 12 in. on the sides and 12 in. on the top. I would call the building department that inspects your jobs and check with them.

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From contributor U:
Below is an image from a fireplace insert company. I've used it often to set distances. I would still check with local codes, though.

Click here for higher quality, full size image

Here are side clearances, same manufacturer. By the way this was a gas insert.

Click here for higher quality, full size image

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From contributor J:
I am a professional mantel builder and we get this question often. Basically the answer is very simple if it is a manufactured firebox. A manufactured fireplace is an appliance, it is therefore listed and approved by U.L. You must follow the manufacturer’s listed instructions.

Mason built fireplaces are a different story, you must follow the adopted code of the area. Most codes require 6" clearance from the firebox opening for combustible material projecting no more than 3/4" from face with a graduated distance equal to 1" distance for every additional 1/8" of projection. Once at 12" clearance there is no restriction as to projection.