The exception 4:

4. Exposed combustible mantels or trim is permitted to be placed directly on the masonry fireplace front surrounding the fireplace opening, provided such combustible materials shall not be placed within 6 inches (153 mm) of a fireplace opening. Combustible material directly above and within 12 inches (305 mm) of the fireplace opening shall not project more than 1/8 inch (3.2 mm) for each 1-inch (25 mm) distance from such opening. Combustible materials located along the sides of the fireplace opening that project more than 11/2 inches (38 mm) from the face of the fireplace shall have an additional clearance equal to the projection.

This is speaking of the placement of the mantle, it states that a mantle can be within 6" of the opening but it wont be thicker then 1/8x(how many inches away it is).

What I have found some inspectors say is that because of the height of the firebox the mantle is not backed by 8" of masonry, so they refuse to let the mantle be placed lower then the 8" of masonry,(which in most cases is directly above the damper).

What is sounds like you are asking is a 3 fold question. One question is about a raised firebox and question 2 is about if you can have a flush hearth with a raised firebox. Question 3 is about the width of the surround.

Question 1: Yes you can have a raised firebox with a flush hearth
Question 2: No you cannot have a 16" hearth( here in Mass)
Question 3: According to the Exception you can have a minimum of 6" firebox to the bottom of the mantle as long as it isnt thicker than 1/8x6.

 

The exception 4:
What is sounds like you are asking is a 3 fold question. One question is about a raised firebox and question 2 is about if you can have a flush hearth with a raised firebox. Question 3 is about the width of the surround.

Question 1: Yes you can have a raised firebox with a flush hearth
Question 2: No you cannot have a 16" hearth( here in Mass)
Question 3: According to the Exception you can have a minimum of 6" firebox to the bottom of the mantle as long as it isnt thicker than 1/8x6.

Yes it was 3 fold q.

q2: based on http://publicecodes.citation.com/st/ca/st/b200v10/st_ca_st_b200v10_21_sec011_par018.htm my understanding is, that hearth extension has to be at least 16", right?

q3: So if you take a look at the photo I attached, wood mantel can not be closer then 12" on the side or on the top, right?

Thank you,

Vadim

 

No. You need a 20" hearth unless you have a fireplace that is less than 20 sq.ft.. you can have the mantle within 8" on the sides of the fireplace and within 6 on the top as described. 12" is the standard from what I normally see.

 

but based on "Combustible material directly above and within 12 inches (305 mm) of the fireplace opening shall not project more than 1/8 inch (3.2 mm) for each 1-inch (25 mm) distance from such opening." I understand that if I want to put wood mantel say 8" on the side, it can not be more than 8/9=1", right?

So let's take mantel in the picture. It looks like sides are 4x8 and top is 6x6. Are you saying that sides can be 6" from for opening and top is 8"? Even that sides are sticking out 4" and top is sticking out 6"?

Thanks.

Vadim

PS: I am not saying that 6"&8" will look nice, just trying to understand the code.

 

Distance from top of opening to throat is 8"

 

Fireplace is already there, so I am not touching insides, just mantel.

Currently it is a gas brick fireplace, with fake stone on the brick and on the hearth extension/self.

Idea is to put granite or marble around the opening, then wooden surrounding. Hearth extenuation also as a slab of granite/marble, same level (or slightly raised) as the hardwood floor.

Thanks,

Vadim

 

The original picture the mantle is 8" on the sides and is made out of what looks like 7/8 or maybe 5/4 . The second pic is an insert fireplace. Those might have different codes.....I know they don't hold them to 10 and 2 !

Typicaaly I have never seen mantles less then 8" and the ones that are built out are right to the edge of the fireplace or 12".

You can't go wrong with a 12" tile or whatever your doing.

 

For a non combustable fireplace you might be able to make a smaller hearth.

 

Thank you,

Vadim