The location and spacing of piers depends upon the dimensions of the home, the live and dead loads, the type of construction (single-or multi-section), I-beam size, soil bearing capacity, footing size, and such other factors as the location of doors or other openings.

Mate-line and column pier supports must be in accordance with this subpart and consistent with Figures A through C to this section, unless the pier support and footing configuration is designed by a registered professional engineer or registered architect.

Piers supporting the frame must be no more than 24 inches from both ends and not more than 120 inches center to center under the main rails.

Pier support locations. Pier support locations and spacing must be presented to be consistent with Figures A and B to § 3285.312, as applicable, unless alternative designs are provided by a professional engineer or registered architect in accordance with acceptable engineering practice.

1. Bottom of footings must extend below frost line depth, unless designed for placement above the frost line. (See § 3285.312(b)).

2. Piers may be offset up to 6 in. in either direction along the supported members to allow for plumbing, electrical, mechanical, equipment, crawlspaces, or other devices.

3. Single-stack concrete block pier loads must not exceed 8,000 lbs.

4. Prefabricated piers must not exceed their approved or listed maximum vertical or horizontal design loads.

5. When a full-height mating wall does not support the ridge beam, this area is considered an unsupported span—Span B.

6. Piers are not required at openings in the mating wall that are less than 48 inches in width. Place piers on both sides of mating wall openings that are 48 inches or greater in width. For roof loads of 40 psf or greater, a professional engineer or registered architect must determine the maximum mating wall opening permitted without pier or other supports.

1. Bottom of footings must be below the frost line depth, unless designed for placement above the frost line. (See § 3285.312(b)).

2. Piers may be offset 6 in. in either direction along supported members to allow for plumbing electrical, mechanical equipment, crawlspaces, or other devices.

3. Single stack concrete block pier loads must not exceed 8,000 lbs.

4. Piers are not required at openings in the mating wall that are less than 48 inches in width. Place piers on both sides of mating wall openings that are 48 inches or greater in width. For roof loads of 40 psf or greater, a professional engineer or registered architect must determine the maximum mating wall opening permitted without pier or other supports.

5. When a full-height mating wall does not support the ridge beam, this area is considered an unsupported span—Span B.

6. In areas where the open span is greater than 10 ft., intermediate piers and footings must be placed at maximum 10 ft. on center.

7. Prefabricated piers must not exceed their approved or listed maximum horizontal or vertical design loads.

8. Column piers are in addition to piers required under full-height mating walls.

1. Mate-line column support piers are installed with the long dimension of the concrete block perpendicular to the rim joists.

2. Pier and footing designed to support both floor sections. Loads as listed in Table 3 to § 3285.303 are total column loads for both sections.