EDT 51-Floor Plan Design1 Weekend Cabin Retreat Project Basements Sacramento City College EDT 51 Kenneth Fitzpatrick, P.E.

2EDT 51-Floor Plan Design Wood Foundation-Basement u The site is excavated to the regular depth. u Plumbing lines are installed u Foundation drainage is installed. u A basement sump should be installed in poorly drained soils or where ground water is a problem.

3EDT 51-Floor Plan Design Wood Foundation-Basement u The bottom of the excavation is covered with 6 to 8 in. of porous gravel or crushed stone. u This material is carefully leveled. u Pressure-treated foundation footing plates made of u 2 x 8 u 2 x 10 u 2 x 12

4EDT 51-Floor Plan Design Wood Foundation-Basement u The foundation walls (2 x 4 or 2 x 6 stud frame) are erected on these plates.

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7 Wood Foundation-Basement u Nails and other fasteners should be made of silicon bronze, copper, or hot-dipped zinc-coated steel. u Special caulking compounds are used to seal all joints in the plywood sheathing. u Lumber and plywood that comes in contact with the ground should be pressure-treated with waterborne preservative salts (ACA or CCA).

8EDT 51-Floor Plan Design Wood Foundation-Basement u After the basement wall is in place, the porous gravel or crushed stone base is covered with a polyethylene film (6 mil thick). u The floor joists or trusses are then installed on the double top plate of the foundation wall.

9EDT 51-Floor Plan Design Wood Foundation-Basement u Before backfilling, a 6 mil polyethylene film should be applied to sections of the wall below grade to serve as a moisture barrier. u All joints should be lapped at least 6 in. and sealed with adhesive.

10EDT 51-Floor Plan Design Wood Foundation-Basement u The top edge of the film should be bonded to the wall at grade level with adhesive. u A treated wood strip is attached along this edge and caulked. It serves as a guide for backfilling. u Backfilling should not begin until the basement floor has cured and the first floor is installed.

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12EDT 51-Floor Plan Design Concrete/Masonry Basement Walls u Several factors influence the strength and stability of a concrete or masonry basement wall to resist earth pressure. u height and thickness u the bond of the mortar u vertical loading u support from crosswalls u pilasters or wall stiffeners u support provided by the first-floor framing

13EDT 51-Floor Plan Design Concrete/Masonry Basement Walls u Pilasters, can be used to strengthen the basement wall. u Pilasters are built at the same time the basement wall is laid.

14EDT 51-Floor Plan Design Concrete/Masonry Basement Walls u Pilaster block are frequently used for such construction u Pilaster blocks are 16 in wide u 8” basement wall project 8 in. inside. u 10” basement walls project 6 in. inside. u 12” basement walls - not required.

15EDT 51-Floor Plan Design Concrete/Masonry Basement Walls u Pilasters are also used for additional support for girders or beams. u Pilasters may also be required to stiffen concrete foundation walls.

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