Thread: crawl space cupport walls

Is there not supposed to be a moisture barrier under the support wall in a crawlspace, also is there a code that requires this wall to be lag bolted to foundation?

Go online to your municipality to see which (adopted) code to reference, then check here: International
Typically vapor barrier surrounds penetrations. Apply sealant at edges and laps.

Originally Posted by cory nystul

Is there not supposed to be a moisture barrier under the support wall in a crawlspace, also is there a code that requires this wall to be lag bolted to foundation?

Wood is required to be either pressure treated (or be one of the durable wood species) when in contact with concrete or separated from the concrete if not pressure treated.

From the IRC: (underlining and bold are mine)
- SECTION R317 PROTECTION OF WOOD AND WOOD BASED PRODUCTS AGAINST DECAY
- - R317.1 Location required.
- - - 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 for the species, product, preservative and end use. Preservatives shall be listed in Section 4 of AWPA U1.
- - - - 1. Wood joists or the bottom of a wood structural floor when closer than 18 inches (457 mm) or wood girders when 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. All 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.
- - - R317.1.1 Field treatment.
- - - - Field-cut ends, notches and drilled holes of preservative-treated wood shall be treated in the field in accordance with AWPA M4.
- - - R317.1.2 Ground contact.
- - - - All wood in contact with the ground, embedded in concrete in direct contact with the ground or embedded in concrete exposed to the weather that supports permanent structures intended for human occupancy shall be approved pressure-preservative-treated wood suitable for ground contact use, except untreated wood may be used where entirely below groundwater level or continuously submerged in fresh water.
- - - R317.1.3 Geographical areas.
- - - - In geographical areas where experience has demonstrated a specific need, approved naturally durable or pressure-preservative-treated wood shall be used for those portions of wood members that form the structural supports of buildings, balconies, porches or similar permanent building appurtenances when those members are exposed to the weather without adequate protection from a roof, eave, overhang or other covering that would prevent moisture or water accumulation on the surface or at joints between members. Depending on local experience, such members may include:
- - - - - 1. Horizontal members such as girders, joists and decking.
- - - - - 2. Vertical members such as posts, poles and columns.
- - - - - 3. Both horizontal and vertical members.
- - - R317.1.4 Wood columns.
- - - - Wood columns shall be approved wood of natural decay resistance or approved pressure-preservative-treated wood.
- - - - - Exceptions:
- - - - - - 1. Columns exposed to the weather or in basements when supported by concrete piers or metal pedestals projecting 1 inch (25.4 mm) above a concrete floor or 6 inches (152 mm) above exposed earth and the earth is covered by an approved impervious moisture barrier.
- - - - - - 2. Columns in enclosed crawl spaces or unexcavated areas located within the periphery of the building when supported by a concrete pier or metal pedestal at a height more than 8 inches (203 mm) from exposed earth and the earth is covered by an impervious moisture barrier.
- - - R317.1.5 Exposed glued-laminated timbers.
- - - - The portions of glued-laminated timbers that form the structural supports of a building or other structure and are exposed to weather and not properly protected by a roof, eave or similar covering shall be pressure treated with preservative, or be manufactured from naturally durable or preservative-treated wood.

Anchorage of the interior walls may depend on local code.

Agreed the wood should be preservative treated or have a moisture barrier under it in accordance with R317.1 location 3

However R317.1.4 exception 2 permits wood to be on concrete that is more than 8 inches above ground covered with a moisture barrier. IMO would apply for the crawl space location though the cripple wall is not a column per se.

In contradiction R317.1 location 2 allows the exceptions for exterior walls that are 8 inches or more above the exposed ground.

[QUOTE=Francis Vineyard;251514]Agreed the wood should be preservative treated or have a moisture barrier under it in accordance with R317.1 location 3]


May have inadvertently left out "naturally durable wood" (from above quote) as an option, such as (non sapwood) redwood or cedar for use as sill plate on footing in crawl without running moisture barrier under it.

There are certainly moisture stains on the studs.
Need more info to make a definite call. Age, relative location, history, etc.

That looks like old construction and later, someone added the vapor barrier. In old construction, I never see treated lumber. I suggest inspecting and probing the bottom plate for rot.