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This guideline is intended to provide the homeowner/contractor with the basic information needed to apply for a building permit to construct an attached garage.

1. Fill out and sign application for a building permit.

2. Submit four (4) separate copies of your plot (site) plan drawn to scale showing existing structures and the proposed addition and its perpendicular distances to the lot lines and from other structures on the lot, if any.
   

   Site plans must show water run-off (use arrows to indicate flow of water) away from the structure.

3. Obtain zoning approval from the St. Louis County Department of Public Works (if unincorporated) or from municipality. In municipalities site plans must be marked "Approved" and Municipal Approval Form submitted prior to permit issuance.

4. Submit four (4) separate complete sets of detailed building construction plans drawn to scale containing the following:

   Foundation and Floor Plans @ 1/4" = 1'-0"
   Elevations @ 1/4" = 1'-0"
   Sections and Details @ min. 3/4" = 1'-0"
   

   Include one of the following in your plan submittal depending on choice of roof framing systems:

   1. If by conventional method, indicate size and spacing of rafters, ceiling joists, and/or ties, on the sections and details included in the plans submitted.
   2. If by the "truss" method, submit four (4) copies of the engineer's sealed truss plan which can be obtained from the lumber dealer or the "truss" fabricator. Trusses to comply with AFPA NDS-91 and TPI 1-95.

5. All electrical work must be performed in accordance with St. Louis County Codes and Ordinances by a licensed/electrical contractor or a pre-authorized Homeowner who by examination has demonstrated the necessary knowledge and ability to perform the work.

Refer to the attached drawings and the following listing of common code requirements pertaining to most attached garages for additional information that needs to be included on the building construction plans.

Footings

6" thick x 12" minimum width with key, bottom of footing minimum 30" below finish grade.

Foundation Walls

8" minimum width, minimum 8" above finish grade (Note-foundation wall/footing may be a single pour if wall is flared at bottom to the required footing bearing width and thickness).

Sill Plate Anchorage

1/2" diameter anchor bolts, 8" minimum embedment, 8' maximum o.c. spacing and at ends/corners with 1-1/2" diameter washers and nuts. Minimum 2 bolts per plate regardless of length.

Exterior Wall Framing

2 x 4 studs 16" o.c. or (2 x 6 @ 24" o.c. max.)
2 x 4 bottom plate and 2 - 2 x 4 top plate (2 x 6 plates with 2 x 6 studs)

Roof Framing

All roof framing shall be designed to support the following minimums:

Top chord of trusses or roof rafters L.L. 20 lb. per sq. ft.
Ceiling joists D.L. 10 lb. per sq. ft.

Exceptions:

1. D.L. plus L.L. 20 lb. per sq.ft. required for those portions of the attic with a clear height between the joist and rafter of 42" or more.
2. D.L. may be reduced to 5 lb. per sq.ft. where either condition applies:
   1. Clear height between the joist and rafter is not over 30".
   2. Clear height between the joist and rafter of greater than 30" does not occur for more than 12" horizontally.

Bottom chord of trusses D.L. 10 lb. per sq.ft.
Note: Applicable only to the following situations

1. Attic trusses with a web configuration that will not permit a rectangular space of 42" vertically x 24" horizontally between the webs and bottom chord.
2. Attic trusses with a web configuration that will allow a rectangular space of 42" vertically x 24" horizontally between the webs and bottom chord, provided all of the following occur:
   1. Attics with drywall ceilings below that are accessed only by a 22" x 30" scuttle opening without a pull-down stairway.
   2. Warning signs attached to the trusses on each side of the opening at least 36" above the bottom chord and within 18" of the edge of the opening. The signs shall be constructed of metal or other approved durable materials suitable for the location and be a minimum of 40 sq. inches in area with 3/4" minimum high letters on a contrasting background that reads "WARNING-TRUSSES NOT DESIGNED FOR ATTIC STORAGE".
   3. Attic areas over garage areas with drywall ceilings shall also be provided with a horizontal railing attached to the trusses on each side of the opening at least 24" and not more than 36" above the bottom chord. The railing is intended to be an obstruction to easy access for storage and shall be constructed of either 1x4's, 2x4's or 3/8"x6" plywood. It may be shop or field applied.

   Exceptions:

   1. D.L. plus L.L. 20 lb. per sq.ft. to be applied when the attic truss has a web configuration that will allow a rectangular space of 42" vertically x 24" horizontally between the webs and bottom chord, provided either A plus B, or C occur:
      1. The attic is accessible by a permanent stairway or pull-down stairway, and;
      2. The pitch of the bottom chord is less than 2:12, or;
      3. Garages without a drywall ceiling.
   2. D.L. may be reduced to 5 lbs. per sq.ft. or the actual dead load where either or both of the following conditions apply:
      1. Clear height between the bottom chord and any other member of the truss does not exceed 30".
      2. Clear height between the bottom chord and any other member of the truss exceeds 30" for not more than 12" horizontally.

Wall and Roof Sheathing

Wall Sheathing: 1/2" intermediate grade sheathing or equal, BOCA approved, nailed with 1 1/2" galvanized roofing nails, or 6d common nails, (location - 3" o.c. along edge, 6" o.c. intermediate).

Roof sheathing: Where trusses or rafters are spaced 24" o.c. roof panel sheathing shall be a mini mum of 1/2" thick without edge support or a minimum of 3/8" thick with edge support. Edge support shall be tongue-and-groove edges, panel edge clips (at mid-point between each support) or 2X lumber blocking. Nailing shall be 6d common for 3/8" and 1/2" sheathing and 8d common for sheathing greater than 1/2" (location - 6" o.c. along edges, 12" o.c. intermediate).

Garage Floor Slab

Minimum thickness of concrete floor slabs supported directly on the ground is 3 1/2". The slab shall be placed over a minimum 4" base course of gravel or crushed stone.

Roofing Underlayment and Covering

All underlayment to be a minimum of Type 1 per ASTM D226-95. (Type 1 is commonly called No. 15 asphalt felt.)

Corrosion-resistant metal flashing is required at all roof intersections, roof and wall intersections and intersection with chimneys. Rolled roofing or two (2) layers of Type 1underlayment may be substituted for flashing at the roof valley provided the shingles are interlaced.

The underlayment shall be installed to extend at least 18 inches beyond a roof valley or hip from either direction.

Asphalt roll roofing installed on roofs of less than 3:12 shall be applied parallel to the eaves. It shall not be installed on roof slopes below 1:12. A single layer of underlayment is required when less than 4:12.

Asphalt and fiberglass shingles shall be laid with a single-layer of Type 1 underlayment applied in shingle fashion over the entire roof for all roof slopes less than four units vertical in 12 units horizontal (4:12). Asphalt shingles shall not be installed on roof slopes below 2 units vertical in 12 units horizontal (2:12).

An ice shield is required under the shingles/roofing of 2 layers of Type 1 underlayment cemented together or of an approved waterproofing membrane extending from the edge of the eave to at least 24" measured horizontally inside the exterior wall line where (a) the roof slope is greater than or equal to 4:12 and the eave overhang is less than 12" measured horizontally from the sheathing to the outside face of the gutterboard, or where (b) the roof slope is less than 4:12 and greater than or equal to 2:12.

Siding

Owners choice of finish weather-resistant siding.

Garage Separation

Wall between garage and existing residence must be protected with 1/2" drywall on the garage side of the wall. This is normally obtained by removing siding and applying 1/2" drywall from foundation to underside of roof sheathing on this wall of garage or on wall and across the garage ceiling. Any existing attic vents and windows must be blocked up and covered with 1/2" drywall. Required vents and windows must be relocated or alternative artificial ventilation methods provided. Doors in this wall must be 1 3/4" solid core wood doors or 1 3/4" solid or honeycomb core steel door.

Caution: Many Fire Departments/Districts may have other requirements such as requiring Type X listed drywall, etc.

Electrical

Interior light with switch at a man-door to residence and/or to exterior door.
Minimum one ground fault circuit receptacle.
Electrical light outside each man door to the exterior. Lights must be switched from inside garage.

The preceding requirements apply to most garage additions, however, the Plan Reviewer may determine that unusual circumstances dictate the need for additional information on any particular project.

For structures 5' or closer to a property line consult both Zoning (Unincorporated Area) and Building Plan Review within the Department of Public Works.

For more information on building an Attached Garage, please visit the following Attached Garage sites.

Plot Plan - 76K
Elevation and Detail Drawing - 111K

Revised: 9/13/94, 2/9/98, 3/27/02

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