Page 247 - Masonry and Concrete

Footings, Foundation Walls, Basements, and Slabs
246 CHAPTER SIX

block foundation walls, screen block of the type described in Chapter
9 may be used if they are properly fitted with screen wire on the inside
of the wall. An 18 in. 24 in. minimum access opening must also be
provided through the foundation wall to permit servicing and inspec-
tion of underfloor areas.
Where a crawl space is provided below wood-framed construction,
the wood should be separated from the exposed soil by the minimum
distances shown in Figure 6-50. In addition to separating the wood
framing from the vapor source and allowing for ventilation, these clear-
ances assure adequate access for periodic visual inspection. All form-
work from footing and wall construction should be removed before
proceeding with construction. The Code permits the finish grade in the
crawl space to be at the bottom of the footings unless there is evidence
of a rising water table or inadequate surface water drainage. In these
cases, the finish grade in the crawl space must be the same as the out-
side finish grade unless an approved drainage system is provided.

SUBFLOOR
AND FINISH FLOOR

FLOOR JOIST

BEAM OR GIRDER
18" MIN.

12" MIN. CRAWL SPACE GRADE

FIGURE 6-50
Minimum height of wood framing above crawl space soil. (from Beall, Christine, Thermal
and Moisture Protection Manual, McGraw-Hill, New York).

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