Floor Joists Clearance To Grade

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.

Floor joists clearance to grade.

Section r502 10 of the international residential code states that header joists can be the same size as the floor joists when the header joist span isn t greater than 4 feet but if the header joist span is more than 4 feet you ll need to double the header joist and ensure that it s capable of. Framing of openings require a header and trimmer joists. The minimum clearance between the ground and the wood structural floor joists and girders is primarily for prevention of wood rot that is caused by wood being too close to the moisture in the soil. Floor or finished grade and 6 inches 152 mm above exposed earth and are separated.

So the minimum is 18 for floor joists and 12 for wood beams within the building foundation according to the internaitonal residential code. Additional support for the floor joists is achieved by nailing the ends of the joists into headers. Floor joists girders and posts. This sample table gives minimum floor joist sizes for joists spaced at 16 inches and 24 inches on center o c for 2 grade lumber with 10 pounds per square foot of dead load and 40 pounds of live load which is typical of normal residential construction.

If fir sill plates are to be used for interior partitions a vapor barrier of 6 mil visqueen minimum is required. Clearances of less than 0 5 inch 12 7 mm on tops sides and ends. Scale 1 4 1 is typical size type and spacing of floor joist. Any reinforcement in slabs on grade must have 2 inches of clearance from soil.

Where the header joist span is than 4 trimmer joists and the header joist shall be doubled. Wood siding sheathing and wall framing on the exterior of a building having a. The clearance from grade to the bottom of floor joists in enclosed areas such as crawl spaces under a house is per the crc irc 18 r317 1 location required. Clearance between floor joists and the ground minimum 18 inches clearance between the beams and the ground minimum 12 inches clearance between siding and the ground minimum 6 inches floor framing plan.

Ground clearances some owners and designers might want ground and paving levels that are close to floor levels to avoid having steps between the inside and the outside of a building but this can have a serious effect on material durability and occupant health. True floor joist span calculations can only be made by a structural engineer or contractor.