Thread: Clearance to deck

I need to find out the clearance of the termination (cap) from a factory built unit in close proximity to a walking deck. Its my house and I'm building a guest / pool room and want to have an outdoor fireplace in a patio area attached to the outside wall of the room add. FYI, the box is 12' from the existing structure. If its too high above the deck I'll just scrap it and build it in the yard somewhere.
My thought is it might be the same clearance as a B vent?
Thanks
Marc

The attached is for a masonry built chimney, for a factory-built chimney you would need to look at the installation instructions ... if not available I would fall back to the masonry built chimney termination heights as a minimum until someone proved otherwise, and make that clarification: installation instructions not available, minimum termination height is ... blah, blah, blah ... unless stated differently in installation instructions - which were not available

Wording something like that should cover you unless you were able to determine the manufacturer and chimney style/model then look up the installation instructions.

Wood burning, right?

Originally Posted by Marc M

My thought is it might be the same clearance as a B vent?

Originally Posted by Jim Luttrall

Wood burning, right?

Good point, Jim, I presumed that the reference to "might be the same clearance as a B vent" meant it was wood burning, or at least solid fuel burning - but that presumption may not have been correct.

I'm also rethinking this comment Marc made: "FYI, the box is 12' from the existing structure." - Marc, are you saying that the chimney is 12 feet from the existing structure (away from the wall it is shown in front of, or, are you saying that it is 12 feet from the wall I questioned if it was 10 feet from?

Originally Posted by Jerry Peck

Good point, Jim, I presumed that the reference to "might be the same clearance as a B vent" meant it was wood burning, or at least solid fuel burning - but that presumption may not have been correct.

I'm also rethinking this comment Marc made: "FYI, the box is 12' from the existing structure." - Marc, are you saying that the chimney is 12 feet from the existing structure (away from the wall it is shown in front of, or, are you saying that it is 12 feet from the wall I questioned if it was 10 feet from?

Its 12' from the vertical wall (house). I get the 3-2-10 rule, however, this is So.Cal and I cannot build a wood burner. So that why I was thinking in terms of B vent.
My architect doesn't know and I'm trying to save time in plan check.

You might be able to get a quick answer at the local building dept.

Originally Posted by Marc M

Its 12' from the vertical wall (house). I get the 3-2-10 rule, however, this is So.Cal and I cannot build a wood burner. So that why I was thinking in terms of B vent.
My architect doesn't know and I'm trying to save time in plan check.

Marc,

If it is going to be using a B vent, then it will be gas fueled, and a B vent does not have to meet the requirements of the 3/2-10 rule ... they have to meet the 1+/<8-2-10 rule.

The 1+/<8-2-10 rule is that the height of the B vent is required to meet the minimum height required for the slope of the roof which is a minimum of 1 foot and goes up with the slope of the roof and the size of the B vent, and, the B vent also has to be 2 feet higher than any vertical wall or similar obstruction within 8 feet of it.

The 1+/<8-2-10 rule is not as simple and clear cut as the 3/2-10 rule because:
From the IRC (which California has not adopted in full)
- G2427.6.3 (503.6.4) Gas vent termination.
- - A gas vent shall terminate in accordance with one of the following:
- - - 1. Gas vents that are 12 inches (305 mm) or less in size and located not less than 8 feet (2438 mm) from a vertical wall or similar obstruction shall terminate above the roof in accordance with Figure G2427.6.3.
- - - - (Jerry's note: Gas vents 12" or smaller: see table included in this section, which states that for slopes from Flat to 6/12 have a minimum height of 1.0 feet measured on the high side of the sloped roof. This is the "1+" part of the rule.)
- - - 2. Gas vents that are over 12 inches (305 mm) in size or are located less than 8 feet (2438 mm) from a vertical wall or similar obstruction shall terminate not less than 2 feet (610 mm) above the highest point where they pass through the roof and not less than 2 feet (610 mm) above any portion of a building within 10 feet (3048 mm) horizontally.
- - - - (Jerry's note: Gas vents larger than 12" ... OR ... (yes, "or") ... which are less than 8 feet from a vertical wall or similar obstruction shall be 2' higher than any portion of the building within 10 feet. This is the "<8-2-10" part of the rule, however, if the vent is larger than 12" than this also includes the "1+" part of the rule too.)
- - - 3. As provided for direct-vent systems in Section G2427.2.1.
- - - 4. As provided for appliances with integral vents in Section G2427.2.2.
- - - 5. As provided for mechanical draft systems in Section G2427.3.3.

Thus: 1 foot high minimum above the roof measured from the high side of the slope, AND, if larger than 12" then 2 feet higher than any portion of the structure within 10 feet, AND, if 12" or smaller and less than 8 feet from a wall or similar vertical obstruction it needs to be 2 feet higher than any portion of the structure within 10 feet.

However ... (this is the easy part) ... go look at the B vent you are going to use, read its installation instructions - that will tell you exactly what is required for THAT vent.

And if you end up buying a different B vent, you may need to relocate or raise the vent.

So make sure you buy the one you looked at.

Last note: I suspect that all B vents will require the same height for the same size vent across manufacturers.

fireplaces.com | Outdoor Products

You might want to consider the outdoor gas fireplaces. They vent out an upper louver up against the non-combustible facing. You don't need a tall chimney or chase for these Fps. They are basically outdoor ventfree but made of stainless steel and tested for outdoor applications. Just keep the facing all non-comb.

Got it.. thanks you guys. Much appreciated.