# OSB against concrete



## Rick18071 (Jul 24, 2013)

The dummies poured concrete right up to the bottom of the OSB sheeting on the exterior walls so it was level with the inside slab. There will be vinyl siding 0n the USB. 2009 IBC.

2304.11.2.2 Wood supported by exterior foundation walls. Wood framing members, including wood sheathing, that rest on exterior foundation walls and are less than 8 inches (203 mm) from exposed earth shall be of naturally durable or preservative-treated wood.

This doesn't apply because there is concrete, not earth.

2304.11.2.6 Wood siding. Clearance between wood siding and earth on the exterior of a building shall not be less than 6 inches (152 mm) or less than 2 inches (51 mm) vertical from concrete steps, porch slabs, patio slabs and similar horizontal surfaces exposed to the weather except where siding, sheathing and wall framing are of naturally durable or preservative-treated wood.

This doen't apply because it is not siding.

Can someone fine a section that says how far the USB should be from the concrete?

The concrete parking lot/sidewalk also slopes toward the buiding, but I know where to find that. This job is going to be fun. Owner is building his own mini store. my first inspection they had the underslab plumbing sloped the wrong way. It took 3 more inspections for them to get it right.


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## Sifu (Jul 25, 2013)

IRC 317.1 #2, #7, #5 if you can find a way to apply the IRC.  Stinks to need a code for that, do the plans indicate protection of wood?  I had an a big R2 this past week that used osb as a spacer between the deck girders, I was able to go to the plan that told us they had to use treated for all exterior wood.


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## Rick18071 (Jul 25, 2013)

This is commercal, can't use IRC. Was looking on manufactors directions, all I could find is not to store it on the ground. So I guess it's ok to have concrete against it


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## kilitact (Jul 25, 2013)

You say it's not siding. What is it? I would call it sub siding and use sec. 2304.11.2.6


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## Coder (Jul 25, 2013)

Sounds like it ought to be rotting/molding in no time. Just some random thoughts. How far down into the concrete does it go? Wonder if they could cut the osb flush with the concrete then replace the first 2 ft or so vertically with pt plywood and flashing at the bottom? Then the osb embedded in the concrete could just deteriorate over time and not affect the rest of the wall. More random (and sometimes useless) thoughts can be provided if needed. :cheers


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## Rick18071 (Jul 25, 2013)

It's not embeded. Just the bottom edge is against the concrete.

There is a list of Weather coverings (siding) in table 1405.2. OSB is not listed. Under Vinyle Siding application (1405.14.1) the siding shall be applied over sheeting....

Never herd anyone call OSB siding, it's sheeting.


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## Forest (Jul 25, 2013)

Rick18071

            The best answer I could fine in the 2009 IBC was in section 1403.In 1403.2 under exceptions were testing required to prove resistance to wind driven rain at intersections of dissimilar materials in reference to exterior wall weather resistance.


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## jar546 (Jul 25, 2013)

If this is commercial, how is this detailed on the approved plans?

Is the RDP aware of this situation?

In an attempt to protect the building owner, I would get them on site, show them and explain the long term effects.  Sometimes the owner who is paying the bills can control a common sense item that the code does not.


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## Frank (Jul 25, 2013)

Not sure what your climate is, but in central VA I would give that design about 3-5 years to failure of the OSB and the studs it is attached to if it is in the shade or on the north side of the building.

At that time removal of the osb and the bottom foot of the wood studs will be doable bare handed


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## tmurray (Jul 25, 2013)

Is there a capillary break in the concrete?


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## Rick18071 (Jul 25, 2013)

No capillary break. Poured the concrete without any inspection first. Owner is the builder. I will be meeting with him next week. I don't have the plans on hand, kept in a different office. I just wanted a code section I could quote. Any idea how far the OSB should be from the concrete?


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## David Henderson (Jul 25, 2013)

The 2010 CBC is based on the 2009 IBC says wood siding 6" from earth, 2" from concrete 2304.11.2.6


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