(A) Floating mat foundations.
(1) A floating mat type foundation shall be defined as a slab with or without a foundation wall that does not rest on adequate bearing soil, but by its design will remain somewhat permanent with or without periodic adjustments.
(2) In no instance will floating mat type foundations be permitted for use on any type of primary structure, or for any structure having gas, water or sewer lines serving it. Use of a floating mat slab is subject to the review and approval of the Building Commissioner, and is intended to be used only when no other design method is feasible.
(B) Capped foundations.
(1) CAPPED FOUNDATIONS shall be defined as construction where a concrete slab, in a separate pour, is placed on top of foundation walls.
(2) In no instance will capped foundations be permitted for use on any type of primary residential structure.
(C) Monolithic slabs and foundations.
(1) MONOLITHIC SLABS and FOUNDATIONS shall be defined as a single poured foundation wall and slab or as a slab with a grade beam.
(2) Monolithic slabs and foundations shall only be permitted, for residential use, when use on a detached accessory structure.
(D) Isolation slabs.
(1) ISOLATION SLABS shall be defined as a concrete slab or floor surrounded by a foundation wall.
(2) Isolation slabs will be permitted, for use in the construction of a primary residential structure or additions, at any elevation in comparison to the exterior grade elevation.
(3) The
AVERAGE EXTERIOR GRADE ELEVATION shall be defined as the elevation of the final grade measured, at a point one foot perpendicular to the outside foundation wall and then the average elevation of that measurement surrounding the slab, on the exterior of the building.
(4) Attached garages, at any elevation, may also be constructed using an isolation slab.
(E) Restrictions. Wherever slabs or slab type construction or floors are permitted the following restrictions will apply:
(1) No warm air heating ducts, return air ducts or cooling ducts may be permitted below or in the slab.
(2) When the area adjacent to the slab is a heated space, the entire slab or foundation wall above grade and two feet below grade will be insulated. All insulation must have a minimum insulation "R" value of 5.0. All materials used shall be designed for use as foundation insulation. Interior to exterior insulation installations, shall overlap a minimum of 12 inches.
(3) Isolation slabs must be constructed using a minimum ¼-inch expansion joint around the entire perimeter of the slab and adjacent to all columns, walls, or other similar units penetrating the slab.
(4) All slabs used as a base of a floor or as a finished floor, in a habitable space or used in a primary structure, other than an attached garage space will have:
(a) A minimum thickness of four inches;
(b) Been installed over a granular base having a uniform and minimum depth of four inches;
(c) A membrane waterproofing directly under the slab, equal to or better than a four-mil polyethylene film, and having a maximum permeance of 0.20 perms. Where joints exists each joint shall be lapped a minimum of four inches.
(5) Where interior bearing walls or partitions rest on the slab. the construction of the slab will required that the slab be thickened to a minimum ten-inch depth, 20-inches wide. Continuous reinforcement bars ( minimum #4 bars ) shall be used, in construction with acceptable engineering standards.
(6) All slabs will require that a minimum 10 ga., welded wire mesh, or an equal be used in the construction.
(7) No floor slab shall be placed in water or on a soft wet subgrade. Subgrades below the exterior grade elevation must be pumped dry at last 24 hours before pouring concrete.
(8) All subgrades must be level, thoroughly compacted and free of all vegetation.
(Ord. 89-23, passed 7-26-89)