Air gap between wood floor framing and concrete porch

[Yikes]

I have a client with a raised wood floor - a 1950s house that is legally used as an office. They need to add an accessible ramp and porch to the front door, and they want the porch made out of concrete. That means the concrete will sit against the rim joist of the building.

I thought I remembered something in the code about needing a 2" horizontal air gap between concrete retaining walls, planter walls, etc. and untreated structural wood framing. I can't find it in the IBC. The closest I got was 2304.11.2.6.

Is there a requirement?

(FYI, I plan on adding a raised curb and heavy flashing to weep the wall rainscreen away from the building. So at this point, I'm mainly focused on termites or decay.)

 

[NYC4310]

Section 2304.11.4.2

I have a client with a raised wood floor - a 1950s house that is legally used as an office. They need to add an accessible ramp and porch to the front door, and they want the porch made out of concrete. That means the concrete will sit against the rim joist of the building.I thought I remembered something in the code about needing a 2" horizontal air gap between concrete retaining walls, planter walls, etc. and untreated structural wood framing. I can't find it in the IBC. The closest I got was 2304.11.2.6.

Is there a requirement?

(FYI, I plan on adding a raised curb and heavy flashing to weep the wall rainscreen away from the building. So at this point, I'm mainly focused on termites or decay.)

I would imagine in this application that section 2304.11.4.2 Would apply. No air gap but some type of moisture barrier would be required.

 

[conarb]

This has always been a problem with front porches and some patios, all I've ever done is install sheet metal (copper in more expensive homes) from the top of the joists down a few inches below the mudsill, no inspector has ever disapproved it.

 

[north star]

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[Milt]

The code section you are looking for is 2304.11.2.5 2012 IBC that specifies 1/2". 2" is for clearance from siding to concrete steps, porch slabs, Patio except were naturally durable or pressure treated.

 

[mark handler]

Yikes

Under the old code "UBC" there was a 2"requirement that is not in the IBC series. It was 2" to a planter.

 

[Yikes]

YikesUnder the old code "UBC" there was a 2"requirement that is not in the IBC series. It was 2" to a planter.

Thanks Mark! I found an '85 UBC 2516.7 that said 2" separation between building walls and planter walls.

 

[mark handler]

You are dating yourself, or was that me.....