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Chapter 15.16
DESIGN AND CONSTRUCTION STANDARDSSections:
15.16.005 Climatic and geographic design criteria.
15.16.010 Snow load.
15.16.020 Wind load and exposure.
15.16.030 Footing depth.
15.16.040 Seismic zone.
15.16.050 Concrete reinforcement.
15.16.060 Post frame structures (pole buildings).
15.16.005 Climatic and geographic design criteria.
Table R301.2(1)
Snow Load
Wind Speed (mph)
Seismic Design Category
Subject to Damage From
Winter Design Temp.
Ice Shield Under-layment Required
Flood Hazard
Air Freezing Index
Mean Annual Temp.
Weathering
Frost Line Depth
Termite
Decay
Min. 35 PSF
85 mph
C
Severe
24 inches
Slight to Moderate
None to Slight
5°
Yes
Yes
1060
51.5°
(Res. TLS 04-41 Exh. A (part))
15.16.010 Snow load.
The minimum snow load design standard is thirty-five pounds per square foot. The building official may increase the snow load requirement on a case-by-case basis, when, based upon location of the structure, the minimum standard is inadequate. Increased requirements shall be based on analysis of local climate and topography and the most current edition of the publication entitled Snow Load Analysis for Washington, as published by the Structural Engineers Association of Washington. (Res. TLS 04-41 Exh. A (part): Ord. TLS 01-02-06B Exh. A (part))
15.16.020 Wind load and exposure.
The minimum basic wind speed design standard is eighty-five miles per hour. The wind exposure category shall be determined by structure location. (Res. TLS 04-41 Exh. A (part): Ord. TLS 01-02-06B Exh. A (part))
15.16.030 Footing depth.
The bottom of footings shall be a minimum of twenty-four inches below finished grade. (Res. TLS 04-41 Exh. A (part): Ord. TLS 01-02-06B Exh. A (part))
15.16.040 Seismic zone.
The International Residential Code seismic design category for Douglas County is C. (Ord. TLS 06-03-43C: Res. TLS 04-41 Exh. A (part): Ord. TLS 01-02-06B Exh. A (part))
15.16.050 Concrete reinforcement.
All concrete slabs, footings, foundations, and concrete masonry units shall incorporate steel reinforcement. (Res. TLS 04-41 Exh. A (part): Ord. TLS 01-02-06B Exh. A (part))
15.16.060 Post frame structures (pole buildings).
A. Post frame structures over twelve hundred square feet in area shall be designed by a professional, licensed by the State of Washington to design such buildings. The licensed professional shall affix his/her certification and signature to the design, including design drawings and details, specifications, and calculations. Any changes to the design, drawings, details, specifications, and calculations during review or construction shall be prepared and certified by the licensed professional designer of record and submitted for approval of the building official prior to incorporating such changes into the work. The minimum design criteria for post frame structures are as follows:
1. Minimum snow load is thirty-five pounds per square foot (PSF). Reductions in live load/snow load are not permitted.
2. The minimum roof purlin dead load is five PSF.
3. The maximum total load deflection is:
a. With ceiling: L/two hundred forty;
b. Without ceiling: L/one hundred eighty.
4. The maximum wall wind load deflection is L/120.
5. If the building design utilizes skin diaphragm for shear, then all of the following sheathing fastening details shall be shown on the plans, in addition to all of the standard framing and embedment details:
a. Fastener size and spacing.
b. Panel-to-panel fastening detail.
c. Panel-to-purlin/girt fastening detail.
d. Panel-to-chord fastening detail.
e. Roof/wall panel-to-end wall truss detail.
f. Wall panel-to-foundation detail.
g. Diaphragm chord splice detail (roof).
6. Each purlin and girt is required to be stamped with a corresponding lumber grade mark so that the building official can determine if the purlins and girts on site comply with the design requirements. The lumber grade mark shall be clearly visible for verification.
B. As determined by the building official, standard plans for post frame structures with an area of twelve hundred square feet or less shall be accepted for review without professional design certification, unless site conditions exist, such as the following: shallow post embedment due to soil conditions, partial foundations, attachment to existing buildings increasing the overall size to greater than twelve hundred square feet. Professional design certification shall be required in these instances.
C. A site-specific plan shall be submitted for all post frame structures and include, at a minimum: a scaled building dimension layout, truss specifications, truss post connection detail, post embedment detail, purlin/girt detail, post size and certification for below grade use, and all opening/door locations. (Res. TLS 04-41 Exh. A (part): Ord. TLS 01-02-06B Exh. A (part))