We called the Montgomery County government to ask about the code for fireplaces and were told the county now requires 12 inches of noncombustible material (in this case, marble) on all sides. All of the other fireplaces we have looked at have only six to 7½ inches of marble forming the surround.
Is the requirement for a 12-inch surround of noncombustible material based on hard data showing that it is safer than a six-inch surround? Is this being required now in other jurisdictions as well?
A: You apparently were given some bad information, or maybe there was a misunderstanding.
Sonya Burke, community outreach manager for the Montgomery County Department of Permitting Services, said in an email that the county follows the fireplace standards in the 2018 International Residential Code, which have not changed recently.
Section R1001.11, which concerns fireplace clearances, says noncombustible material, such as the marble surround you want, needs to extend at least six inches beyond the fireplace opening on both sides and above. But within 12 inches of the opening, any combustible material, such as wood columns or a mantel, can project only ⅛ of an inch for each inch it is away from the opening.
A mantel six inches above the opening can be only ¾ of an inch deep — so shallow that it wouldn’t look right, especially in a fireplace that’s being outfitted to have a classical look. Even 10 inches up, the mantel could be only 1¼ inches deep, which is still too skimpy. That’s why mantels are usually 12 inches or more above the fireplace opening.
The section doesn’t refer to the size of the opening; the standards apply regardless of the dimensions. But the size of your fireplace opening could affect your options for purchasing ready-made trim kits. Dimensions in kits for mantels and columns start outside the surround, not the firebox, although that’s not always clear in the illustrations that accompany online offerings.
For example, mantelsdirect.com shows a Fremont wooden mantel that appears to come in sizes that would work with your fireplace: One is sized for a 54-by-39-inch opening, the other for a 51-by-36-inch opening. But the “opening” needs to include the band of marble or noncombustible material at least six inches wide. For a fireplace like yours, you would need to add 12 inches to the 47-inch width and six inches to the 31-inch height. That means any ready-made kit would need to be sized for an opening of at least 59 by 37 inches.
As you shop, be aware that 59 by 37 is the minimum. If you want marble that’s more than six inches across, add the appropriate amount when you shop for a mantel kit.
There is no rule saying the marble across the top needs to match the width of the marble on the sides. From an aesthetic standpoint, a surround can look good if it’s taller across the top of the firebox than it is wide on the sides. But a surround that’s wider on the sides than it is across the top will probably look too squat.
Mantel kits usually are made of wood or manufactured wood material, such as MDF — all considered combustible. Many designs have a header that sits under the mantel shelf and runs between the columns. Assuming these will be less than 12 inches from the fireplace opening, make sure the columns and the header fit close enough to the wall, so they project no more than ⅛ of an inch for each inch they are beyond the opening.
If you can’t find what you like in a ready-made kit, consider splurging on a custom design. A fireplace is such a focal point in a room that you want something that fits in.
More detail on no-drill grab bars, from a reader
I read the article about no-drill grab bars and wanted to share extra information. We fretted over installing these in our shower, because, really, how could they last and hold weight? Or so we thought. After watching YouTube videos on installation and speaking directly to the company, we took the plunge. The company advised me on important details: Make sure the tile is smooth. Clean it well. Do not use cleaning agents around the connections to the wall, because they might interfere with the adhesive over time. This last part is very important. I used a razor scraper to remove residual soap scum and some alcohol before I used the supplied cleaning packet. I believe doing that and avoiding typical bathroom cleaners have been important to the bars’ adherence.
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