Fire Separation Distance for Decks

[Paul Sweet]

Several years ago I worked for an architect who designed McMansions along the SC coast. The decks had to be 10 ft. or more above ground to get above the FEMA flood line. They also had to be supported separately from the house, and were separated from the house by an inch or two, probably for seismic reasons if I remember properly. I don't recall having to fire rate any of them, although the localities they were built in had very strict zoning which probably kept them out of the fire separation distance.

There's a lot of difference between a 200 SF or so deck a couple feet off the ground and these huge platforms, so one size won't fit all.

 

[Sifu]

I agree with everything you point out Glen. In searching for more information I came across an ICC forum thread that hinted that ICC was now giving information contrary to the projection interpretation but I haven't been able to confirm it or find out what that information might be. This is the first time I have encountered a property line separation question for a deck, but I have had townhouse issues. In at least one former jurisdiction we required rated wall construction between the decks. I can't remember if we had any minimum extents such as height but I do remember requiring the separation. I suppose a similar method could be used if one absolutely had to have the deck that close to the property line.

 

[Mr. Inspector]

So Glen there are no definition of a deck in the IRC.

So when is it a deck, or a covered deck, or a porch, or a balcony. or just a large landing?

 

[Glenn]

So Glen there are no definition of a deck in the IRC.

So when is it a deck, or a covered deck, or a porch, or a balcony. or just a large landing?

Funny. That's also on my to-do list for 2024. You forgot "elevated walking surface", "patio", "paved surfaces" (for cladding clearances). This terminology is a huge mess.

There was a definition of deck and balcony up until the 2009 IRC.

 

[Sifu]

That's also on my to-do list for 2024.

You are a busy man...but we're better for it so thanks.

 

[Mr. Inspector]

I always question does a simple wood stairway landing landing or a wood porch that is barely off the ground need to build with the deck requirements with tension devices.

 

[classicT]

I always question does a simple wood stairway landing landing or a wood porch that is barely off the ground need to build with the deck requirements with tension devices.

Oooohh.... I want to see Glenn's response to this question. He may just leave you wondering if you ever need tension ties.

 

[Mr. Inspector]

If someone builds a roof over a deck does it now become a Category 1 Sunroom per 2015 IRC 301.2.1.1.1 and it will need stamped plans? In the past I have asked questions about sunrooms on this forum (just search sunrooms) from this section and the AAMA/NPEA/NSA 2100 but only got crickets. Doesn't anyone else comply to this?

 

[tmurray]

The code here requires any platforms built closer then 4' to the property line to be non-combustible.

 

[Glenn]

I always question does a simple wood stairway landing landing or a wood porch that is barely off the ground need to build with the deck requirements with tension devices.

I've done a lot of research into this connection detail in the code and the research others have done on the subject. I put this video together before the 2015 IRC in an attempt to remove the provisions. I was not successful. I have a lot to say about this subject, but if you have not seen this video, please watch it first.

 

[Mr. Inspector]

Thanks but i saw it and it's very interesting. But without a definition of a deck I don't know if a wood Category 1 Sunroom floor, landing, covered deck, porch, etc. can or is is required to be built as the IRC requires for a deck..