Concrete slab against interior or exterior sheathing

[Cinci-hal]

Is there an area of the IRC that address concrete slabs such as garage floors or concrete landings that are above the foundation stem wall and end up being against the interior (drywall) or exterior (OSB) sheathing. I'm looking for such things as clearances, flashing, and expansion joints that would protect against water damage or for other reasons. Could someone point me to the section(s) that would cover that?

 

[Yikes]

You are looking for stated code requirements, not ‘best practice’ details?

 

[Cinci-hal]

You are looking for stated code requirements, not ‘best practice’ details?

Yes...or both. I would prefer not having the concrete slab above the concrete foundation. Owner is asking if we can do concrete above. I am gathering all the information I can to show them the pro's and con's of their ideas and try to offer them solutions. Would like to know what IRC says about it. But if you have best practice opinions, I would be more than happy to hear about those as well.

 

[bill1952]

Isn't this a question of how close to ground it is?

 

[mark handler]

 

[Paul Sweet]

IRC R317 tells where wood and wood-based products must be protected from decay. Metal flashing with a joint filler between it and the slab is usually considered an adequate separation.

 

[bill1952]

Isn't this a question of how close to ground it is?

 

[Paul Sweet]

IRC 317.1 Location Required gives lots of dimensions

"Protection of wood and wood-based products from decay shall be provided in the following locations by the use of naturally durable wood or wood that is preservative-treated in accordance with AWPA U1.

1. Wood joists or the bottom of a wood structural floor where closer than 18 inches (457 mm) or wood girders where closer than 12 inches (305 mm) to the exposed ground in crawl spaces or unexcavated area located within the periphery of the building foundation.
2. Wood framing members that rest on concrete or masonry exterior foundation walls and are less than 8 inches (203 mm) from the exposed ground.
3. Sills and sleepers on a concrete or masonry slab that is in direct contact with the ground unless separated from such slab by an impervious moisture barrier.
4. The ends of wood girders entering exterior masonry or concrete walls having clearances of less than 1/2 inch (12.7 mm) on tops, sides and ends.
5. Wood siding, sheathing and wall framing on the exterior of a building having a clearance of less than 6 inches (152 mm) from the ground or less than 2 inches (51 mm) measured vertically from concrete steps, porch slabs, patio slabs and similar horizontal surfaces exposed to the weather.
6. Wood structural members supporting moisture-permeable floors or roofs that are exposed to the weather, such as concrete or masonry slabs, unless separated from such floors or roofs by an impervious moisture barrier.
7. Wood furring strips or other wood framing members attached directly to the interior of exterior masonry walls or concrete walls below grade except where an approved vapor retarder is applied between the wall and the furring strips or framing members."