Design Load Guidelines

Below is a listing of design load guidelines for each Idaho jurisdiction.

*figures are for guidance only and the jurisdictions should be called directly if there are any questions

Counties

   

Cities

Ada

Seismic Design Category

C

Ground Snow Load

20 psf

Wind Load

90 mph

Live Load

25 psf

Frost Depth

24"

Elevation

Varies.

Exposure

Blaine                       See blainecounty.org

Seismic Design Category

Varies.

Ground Snow Load

Varies.

Wind Load

Varies.

Live Load

Varies.

Frost Depth

Varies.

Elevation

Varies.

Exposure

Bear Lake

www.bearlakecounty.info
Seismic Design Category D1
Ground Snow Load 45 lbs
Live Load 15 lbs
Frost Depth 32 in
Elevation 5964 ft
Exposure C

Butte

Seismic Design Category D1
Ground Snow Load 50 lb
Live Load 35 lb
Frost Depth 30"
Elevation 5350

Camas

Seismic Design Category

C & Do

Ground Snow Load

90, 100, 125 psf

Wind Load

90 mph

Live Load

40 psf

Frost Depth

30 in

Elevation

5052

Exposure

Severe

Canyon

Seismic Design Category

B

Ground Snow Load

25 psf

Wind Load

90 mph

Live Load

Frost Depth

24 in

Elevation

Exposure

C

Clearwater

www.clearwatercounty.org

Seismic Design Category

B

Ground Snow Load

Wind Load

90 mph

Live Load

Minimums per code

Frost Depth

32"

Elevation

varies from 1000 ft to over 3000 ft; approximate elevations for the city limits of: Orofino 1027; Elk River 2918; Pierce 3087; Weippe 3029

Exposure

Elmore

Seismic Design Category

C

Ground Snow Load

120 psf above Tollgate, 30 psi below

Wind Load

90 mph

Live Load

30 psf

Frost Depth

36” above Featherville, 30” above Tollgate to Featherville, 24" below

Elevation

3000 to 7000

Exposure

B and C

Gooding

Seismic Design Category

C

Ground Snow Load

30 psf

Wind Load

90 mph

Live Load

30 psf

Frost Depth

24 in

Elevation

3500 ft

Exposure

C

Fremont

Seismic Design Category

D1

Ground Snow Load

50/90/170 psf

Wind Load

90 mph, 3 sec gusts

Live Load

Snow 35psf/70psf/90psf/128psf over load as per IBC/IRC

Frost Depth

32 in

Elevation

5000-7000 ft

Exposure

Jerome

www.jeromecountyid.us

Seismic Design Category

C

Ground Snow Load

20 psf

Wind Load

115 mph 3 sec gust velocity

Wind Exposure C
Roof Snow Load 30 psf

Live Load

30 psf

Presumed Soil Bearing Pressure 1500 psf without soils investigation

Frost Depth

24 in

Elevation

4048 ft

Climate Zone

5B

Ketchum

Seismic Design Category

D with 35% snow load at time of earthquake. Ss = 73%, S1 = 20.5% or use site specific criteria

Ground Snow Load

120 psf

Wind Load

90 mph

Live Load

100-psf with 100-plf line load @ eaves and unbalanced loading per ASCE7

Frost Depth

24 in

Elevation

Exposure

Kootenai

Seismic Design Category

C

Ground Snow Load

Site specific per U of I publication “Ground and Roof Snow for Idaho”

Wind Load

90 mph 3 second gust

Frost Depth

24 in

Elevation

Site specific; 2128+

Exposure

site specific exposure.

Latah

Seismic Design Category

B

Roof Snow Load

Zones of 30#, 40#, 60#, 80# 100# depending on locations (see County snow load map)

Wind Load

90 mph/3 sec. gusts

Live Load

Soil bearing value 1500 psf

Frost Depth

30 in

Elevation

Range approx.
1400-5000 ft

Soils

U.S. Dept. of Agriculture, Soil Survey of Latah County Area, Idaho, April 1981

Lemhi

Seismic Design Category

B, C, D & D0

Ground Snow Load

 Please contact the local building department for confirmation.

Wind Load

90 mph, 3 sec gust

Live Load
 
Frost Depth

36” below finished grade

Elevation

2500-9000 ft

Exposure
 

Lincoln

Seismic Design Category

D

Ground Snow Load

30#

Wind Load

90 mph, 3 sec gust

Live Load
30#
Frost Depth

24” below finished grade

Elevation

4000 ft +/-

   

Minidoka

Seismic Design Category

C

Ground Snow Load

25 psf

Wind Load

90 mph

Live Load

30 psf

Frost Depth

24 in

Elevation

Exposure

Nez Perce

www.co.nezperce.id.us

Seismic Design Category

B

Ground Snow Load

25 - 70 psf

Wind Load

115 mph

Live Load

30 psf

Weathering

Severe

Frost Depth

24-48 in

Termite

Slight to Moderate

Decay

None to Slight

Winter Design Temp

10 degrees F

Flood Hazards

FIRM maps as currently adopted
Mean annual temp

51 degrees F

Climate zone 5 and Marine 4

Elevation

745 - 4800

Exposure

Owyhee

Seismic Design Category

B

Ground Snow Load

20 psf

Wind Load

90 mph

Live Load

Roof snow load below 6000 ft. 25 psf. Above 6000 ft. 35 psf

Weathering

Severe

Frost Depth

24 in

Termite

Slight to Moderate

Decay

None to Slight 

Winter Design Temp

10 Degree F

Ice shield
Under- layment

Not required

Flood Hazards

FIRM maps as currently adopted

Air Freezing Index

980

Mean Annual Temp

51 Degrees F

Elevation

Exposure

Power

Seismic Design Category

Group I, Site Class D, Design Category D

Ground Snow Load

45 psf

Wind Load

90 mph

Live Load

30psf

Frost Depth

30 in

Elevation

4600-5200 ft

Exposure

Teton

Seismic Design Category

D1

Ground Snow Load

60 -130 psf

Live Load

85 lbs per square ft
+ dead load + drift

Wind Load

90 mph

Frost Depth

32 in

Elevation

6000 ft

Exposure

Twin Falls

www.twinfallscounty.org

Seismic Design Category

C

Ground Snow Load

30 psf

Wind Load

90 mph with 3 second gust

Soil bearing pressure 1500#
Flood zone site specific

Termite

Slight

Frost Depth

24 in min

Elevation

2900-4900 ft

Weathering

Severe

Unless determined differently based on the site evaluation by a qualified design professional. (Ord. 217, 12-16-2010)

Whitman

Seismic Design Category

B

Ground Snow Load

30 psf

Wind Load

85 mph

Live Load

IBC IRC

Frost Depth

32 in. Ice shield under-layment required. Mean annual temp 42 degrees.

Elevation

Exposure

 
   

Acequia

Seismic Design Category

C

Ground Snow Load

25 psf

Wind Load

90 mph

Live Load

30 psf

Frost Depth

24 in

Elevation

Exposure

Ammon

Seismic Design Category

D1

Ground Snow Load

50 psf

Wind Load

90 mph, 3 sec gust

Live Load

Per building code

Frost Depth

30 in

Elevation

Exposure

Blackfoot

Seismic Design Category

Category C; Site Class

Ground Snow Load

30 psf

Wind Load

Exposure C 90mph/105, 3 sec gust

Live Load

30 psf

Frost Depth

30 in

Elevation

4488 ft

Exposure

Boise

Seismic Design Category

2003 IRC is Design Category C. 2003 IBC is based on Section 1614

Ground Snow Load

Per local ordinance it is 20 psf with further statement that snow loads shall be determined per Section 7 of ASCE 7, but the design roof load shall not be less than a uniform snow load of 25 psf

Wind Load

90 mph for both 2003 IRC and 2003 IBC

Live Load

per 2003 IRC and 2003 IBC

Frost Depth

24 in

Elevation

2842 ft

Exposure

Caldwell

Seismic Design Category

B

Ground Snow Load

20 psf

Wind Load

90 mph

Live Load

25 psf

Frost Depth

24 in

Elevation

Exposure

Chubbuck

Seismic Design Category

D1

Ground Snow Load

45 psf

Wind Load

70 mph and 90 mph, 3 sec gust

Live Load

36 psf

Frost Depth

36 in

Elevation

4470 ft

Exposure

Coeur d'Alene

Seismic Design Category

C

Ground Snow Load

60 psf

Wind Load

90 mph, 3 sec gusts

Live Load

40 psf

Frost Depth

24 in

Elevation

2128-2860 ft

Exposure

Fruitland

Seismic Design Category C
Ground Snow Load 25
Live Load 20
Frost Depth 24 in
Exposure C

Gooding

Seismic Design Category

C

Ground Snow Load

30 psf

Wind Load

90 mph

Live Load

30 psf

Frost Depth

24 in

Elevation

3500 ft

Exposure

C

Hailey

Seismic Design Category

D1

Ground Snow Load

143 psf

Wind Load

90 mph

Live Load

100 psf

Frost Depth

24 in

Elevation

Approx. 5600 ft

Exposure

Hayden

www.cityofhaydenid.us

Seismic Design Category

C

Ground Snow Load

60 psf

Wind Load

90 mph, 3 second gusts

Live Load

40 psf

Frost Depth

24 in

Elevation

2287 ft

Exposure

Site specific exposure

Heyburn

Seismic Design Category

C

Ground Snow Load

25 psf

Wind Load

90 mph

Live Load

30 psf

Frost Depth

24 in

Elevation

Exposure

Idaho Falls

Seismic Design Category

D

Ground Snow Load

47 psf

Wind Load

90 mph

Live Load

Frost Depth

30 in

Elevation

4710 ft

Exposure

C

Lewiston

Seismic Design Category

B

Ground Snow Load

30 psf

Wind Load

90 mph, 3 sec gust

Frost Depth

24 in

Elevation

Lowest 739 ft, Highest 1550 ft

McCall

Seismic Design Category

D

Ground Snow Load

150 psf, but the engineered design roof load shall not be less than a uniform snow load of 120 psf

Wind Load

90 mph

Live Load

Varies

Frost Depth

24 in

Elevation

5200 to 5300 ft

Exposure

Varies

Moscow

Seismic Design Category

B

Ground Snow Load

64 psf

Wind Load

90 mph, 3 sec gust

Live Load

Snow 40 psf, minimums per code

Frost Depth

30 in

Elevation

2500 to 2800 ft

Exposure

C

Nampa

Seismic Design Category

2009 IRC
2009 IBC

Ground Snow Load

25 psf, collateral load of 5 psf

Roof Snow Load

20 psf, collateral load of 5 psf

Wind Load

90 mph for both 2003 IRC and 2003 IBC

Live Load

per 2003 IRC and 2003 IBC

Frost Depth

24 inches

Elevation

2600 ft.

Exposure

B or C

Orofino

Seismic Design Category

B

Ground Snow Load

30 psf

Wind Load

90 mph with 3 sec gust

Live Load

25 psf

Frost Depth

24 in

Elevation

1000 ft

Exposure

Paul

Seismic Design Category

C

Ground Snow Load

25 psf

Wind Load

90 mph

Live Load

30 psf

Frost Depth

24 in

Elevation

Exposure

Pocatello

www.pocatello.us

Seismic Design Category

C or D depending on the building classification and engineers calculation Default “D”

Ground Snow Load

45 psf

Wind Load

Per IBC maps 90 mph 3 second gust

Live Load

31.5 lbs with calculations or default 35 lbs

Frost Depth

36 in

Elevation

4250 ft

Exposure

Default C

Prist River

www.priestriver-id.gov
Seismic Design Category C
Ground Snow Load 73
Live Load 50 Residential 60 Commecial
Frost Depth 24"
Elevation 2100
Weathering Severe
Termite None to slight
Decay None
Winter Design Temp 10 Degrees

Rathdrum

Seismic Design Category

C

Ground Snow Load

56 psf

Wind Load

90 mph

Live Load

40 psf

Frost Depth

24 in

Elevation

Exposure

Rexburg

Seismic Design Category

Depends upon rock profile. Usually D but can be C

Ground Snow Load

50 psf

Wind Load

90 mph

Live Load

Same as IBC – IRC

Frost Depth

36 in

Elevation

4865-5080 ft

Exposure

Rupert

Seismic Design Category

C

Ground Snow Load

25 psf

Wind Load

90 mph

Live Load

30 psf

Frost Depth

24 in

Elevation

Exposure

Sandpoint

www.cityofsandpoint.com

Seismic Design Category

C

Ground Snow Load

104 psf

Wind Load

90 mph

Live Load

55 psf

Frost Depth

24 in

Elevation

2075 ft

Exposure

B or C

Soda Springs

Seismic Design Category

D

Ground Snow Load

60 psf

Wind Load

90 mph

Live Load

Frost Depth

36 in

Elevation

5800-6000 ft

Exposure

Spirit Lake

Seismic Design Category

C

Ground Snow Load

56 psf

Wind Load

90 mph

Live Load

40 psf

Frost Depth

24in

Elevation

Exposure

Sun Valley

Seismic Design Category

D1or per IBC Chapter 16

Ground Snow Load

120 psf

Wind Load

90 mph

Live Load

Frost Depth

24 in

Elevation

5920 +/-

Exposure

B

Twin Falls

www.tfid.org

Seismic Design Category

Site class C

Roof Snow Load

25 psf

Ground Snow Load 15 psf.

Wind Load

90 mph, 3 sec gust velocity

Wind exposure B (C in some areas)

Live Load

Per IBC, but Section 1608 is amended to include that the minimum uniformly distributed design load shall be 25 psf

Presumed soil bearing pressure 1500psf without soils investigation

Frost Depth

24 in

Climate Zone 5B
Water heating design temp 2 degrees (99% dry bulb)
Elevation 3700
Exposure Fastest mile/3 second gust 75mph/90mph exposure C.

Table R301.5 is amended to require a minimum uniform live load of 40 psf in habitable attics and sleeping rooms.

Foundations with stem walls shall be provided with a minimum of one # 4 bar at the top of the wall and one #4 bar at the bottom of the footing. #4 vertical bars are required at 6 feet on center.

Basement walls to have one #4 horizontal bar at 4 feet on center. One #4 bar is also required horizontally and vertically around openings, extending 2 feet beyond the opening. One #4 bar to be placed diagonally at corners of openings subject to cracking. Vertical bars installed per IRC.

Unvented fuel-burning appliances are not allowed.

30” minimum crawl space depth measured from bottom of floor joist (per local resolution)

Weiser

Seismic Design Category

C

Ground Snow Load

30 psf

Wind Load

90 mph

Live Load

Per 2009 IRC and 2009 IBC

Weathering

Severe

Frost Depth

24 in

Termite

Decay

Winter Design Temp

Ice shield
Under- layment

Flood Hazards

FIRM Maps Effective date June 16, 2009

Air Freezing Index

980

Mean Annual Temp

50 Degrees F

Elevation

2129

Exposure