Wind-Borne Debris Region and certification reports

Wind-Borne Debris Region and certification reports for insurance companies and mortgage companies

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Impact of Wind-Borne Debris Requirements on Construction Practices

Note: The proposed Florida Building Code allows the use of partially enclosed/internal pressure design for protecting buildings from the impact of wind-borne debris.

The Florida Building Commission contracted several studies to determine the impact of wind-borne debris requirements on construction practices and costs. Data sources are American Forest and Paper Association (AfoPA), Florida Concrete and Products Association and Southern Building Code Congress International (SBCCI). The following is a summary of those study results. (Note: this analysis only addresses exposure B.)

  • •No change to wall framing practices in wind regions under 130 mph.
  • •No change to masonry reinforcement practices in wind regions under 130 mph.
  • •No change to roof framing and sheathing practices in wind regions under 130 mph.
  • •Additional connectors required. Material costs for 1500 sq. ft. house under $100.

Frame Wall Construction:

The attached tables show that conventional framing, #2 spruce, pine, fir, 2×4 16 o.c. fully sheathed with minimum structural panel, is sufficient for partially enclosed/internal pressure worst case design up to 125 mph for 10′ wall heights and 140+ mph for 8′ wall heights. (AFoPA National Wood Design Manual, High Wind Edition, draft revised tables for compliance with ASCE 7-98) [See example attached.]

Masonry Wall Construction:

The Florida Building Commission approved the Florida Concrete and Products Association prescriptive design method, Guide to Concrete Masonry Residential Construction in High Wind Areas for construction of one and two family residential buildings for basic wind speeds of 130 mph or less and exposure B.

Roof Construction:

The engineering analysis of Gary Walker, P.E. and the Southern Building Code Congress International show that common frame roofing with #2 SPF, 2×6, 24″ o.c. framing with 7/16″ minimum structural panel sheathing is sufficient to withstand the additional forces of partially enclosed/internal pressure worst case design.

Connectors: Additional roof anchorage will be needed for basic wind speeds 110 mph and above.

Example: Partially Enclosed, 2 x 4 @ 16 o/c Spruce – Pine – Fir #2

Wind Speed mph 3 sec gusts Stud Length(from Table 3.20A) Exposure BAdjustment Factor (.90) Exposure CAdjustment Factor (.78)
110 12′ – 1″ (12′ – 1″) x (.9) = 10′ – 10″ 9′ – 5″
120 11′ – 5″ 10′ – 5″ 8′ – 11″
130 10′ – 10″ 9′ – 9″ 8′ – 5″
140 10′ – 1″ 9′ – 1″ 7′ – 10″
150 9′ – 4″ 8′ – 4″ 7′ – 3″

Note: Exposure B – Suburban and wooded environment

Exposure C – Waterfront

mo\exposure.wpd

TABLE 3.20A

MAXIMUM EXTERIOR LOADBEARING AND NON-LOADBEARING STUD LENGTHS FOR COMMON LUMBER SPECIES RESISTING INTERIOR ZONE WIND LOADS

(Fully Sheathed with a Minimum Sheathing Material)a

Three Second Gust Wind Speed (mph) 85 90 100 110
Stud
Spacing
(in.)
Species Grade 2×4 2×6 2×8 2×4 2×6 2×8 2×4 2×6 2×8 2×4 2×6 2×8
Maximum Allowable Stud Length (ft.-in.)1
12 Douglas Fir-LarchDouglas Fir-Larch

Douglas Fir-Larch

Douglas Fir-Larch

Douglas Fir-Larch

Hem-Fir

Hem-Fir

Hem-Fir

Hem-Fir

Hem-Fir

Southern Pine

Southern Pine

Southern Pine

Southern Pine

Southern Pine

Spruce-Pine-Fir

Spruce-Pine-Fir

Spruce-Pine-Fir

Spruce-Pine-Fir

Spruce-Pine-Fir

SS#1

#2

Stud

Standard

SS

#1

#2

Stud

Standard

SS

#1

#2

Stud

Standard

SS

#1

#2

Stud

Standard

17-716-11

16-7

15-2

12-7

16-7

16-3

15-6

15-1

12-7

17-3

16-11

16-7

15-10

13-6

16-3

15-10

15-10

15-1

12-7

20-020-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-020-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

16-1116-3

15-11

14-3

11-10

15-11

15-7

14-11

14-3

11-10

16-7

16-3

15-11

14-11

12-8

15-7

15-3

15-3

14-3

11-10

20-020-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-020-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

15-915-2

14-10

12-9

10-7

14-10

14-7

13-10

12-9

10-7

15-6

15-2

14-10

13-4

11-4

14-7

14-3

14-3

12-9

10-7

20-020-0

20-0

19-2

20-0

20-0

20-0

19-2

20-0

20-0

20-0

20-0

20-0

20-0

20-0

19-2

20-020-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

14-914-3

13-11

11-6

9-7

13-11

13-8

13-0

11-6

9-7

14-6

14-3

13-11

12-1

10-3

13-8

13-4

13-4

11-6

9-7

20-020-0

20-0

17-4

20-0

20-0

20-0

17-4

20-0

20-0

20-0

18-4

20-0

20-0

20-0

17-4

20-020-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

16

Douglas Fir-LarchDouglas Fir-Larch

Douglas Fir-Larch

Douglas Fir-Larch

Douglas Fir-Larch

Hem-Fir

Hem-Fir

Hem-Fir

Hem-Fir

Hem-Fir

Southern Pine

Southern Pine

Southern Pine

Southern Pine

Southern Pine

Spruce-Pine-Fir

Spruce-Pine-Fir

Spruce-Pine-Fir

Spruce-Pine-Fir

Spruce-Pine-Fir

SS#1

#2

Stud

Standard

SS

#1

#2

Stud

Standard

SS

#1

#2

Stud

Standard

SS

#1

#2

Stud

Standard

15-1115-4

15-1

13-0

10-10

15-1

14-9

14-1

13-0

10-10

15-8

15-4

15-1

13-7

11-7

14-9

14-5

14-5

13-0

10-10

20-020-0

20-0

19-7

20-0

20-0

20-0

19-7

20-0

20-0

20-0

20-0

20-0

20-0

20-0

19-7

20-020-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

15-414-9

14-6

12-3

10-2

14-6

14-2

13-6

12-3

10-2

15-1

14-9

14-6

12-10

10-10

14-2

13-10

13-10

12-3

10-2

20-020-0

20-0

18-5

20-0

20-0

20-0

18-5

20-0

20-0

20-0

19-6

20-0

20-0

20-0

18-5

20-020-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

14-413-9

13-6

10-11

9-1

13-6

13-3

12-7

10-11

9-1

14-1

13-9

13-6

11-5

9-9

13-3

12-11

12-11

10-11

9-1

20-020-0

20-0

16-5

20-0

20-0

19-10

16-5

20-0

20-0

20-0

17-5

20-0

20-0

20-0

16-5

20-020-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

13-512-11

12-8

9-10

8-2

12-8

12-5

11-10

9-10

8-2

13-2

12-11

12-8

10-4

8-9

12-5

12-1

12-1

9-10

8-2

20-020-0

19-7

14-10

19-11

19-6

18-7

14-10

20-0

20-0

19-11

15-8

19-6

19-1

19-1

14-10

20-020-0

20-0

19-1

20-0

20-0

20-0

19-1

20-0

20-0

20-0

20-0

20-0

20-0

20-0

19-1

24

Douglas Fir-LarchDouglas Fir-Larch

Douglas Fir-Larch

Douglas Fir-Larch

Douglas Fir-Larch

Hem-Fir

Hem-Fir

Hem-Fir

Hem-Fir

Hem-Fir

Southern Pine

Southern Pine

Southern Pine

Southern Pine

Southern Pine

Spruce-Pine-Fir

Spruce-Pine-Fir

Spruce-Pine-Fir

Spruce-Pine-Fir

Spruce-Pine-Fir

SS#1

#2

Stud

Standard

SS

#1

#2

Stud

Standard

SS

#1

#2

Stud

Standard

SS

#1

#2

Stud

Standard

13-1113-5

13-2

10-6

8-8

13-2

12-10

12-3

10-6

8-8

13-8

13-5

13-2

11-0

9-4

12-10

12-7

12-7

10-6

8-8

20-020-0

20-0

15-9

20-0

20-0

19-3

15-9

20-0

20-0

20-0

16-8

20-0

19-9

19-9

15-9

20-020-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

13-512-11

12-8

9-10

8-2

12-8

12-5

11-10

9-10

8-2

13-2

12-11

12-8

10-4

8-9

12-5

12-1

12-1

9-10

8-2

20-020-0

19-7

14-9

19-11

19-6

18-7

14-9

20-0

20-0

19-11

15-8

19-6

19-0

19-0

14-9

20-020-0

20-0

19-1

20-0

20-0

20-0

19-1

20-0

20-0

20-0

20-0

20-0

20-0

20-0

19-1

12-612-0

11-7

8-9

11-10

11-7

11-0

8-9

12-3

12-0

11-10

9-3

7-10

11-7

11-3

11-3

8-9

19-818-9

17-6

13-2

18-7

18-2

17-3

13-2

19-3

18-11

18-5

14-0

18-2

17-6

17-6

13-2

20-020-0

20-0

17-0

20-0

20-0

20-0

17-0

20-0

20-0

20-0

18-1

20-0

20-0

20-0

17-0

11-911-3

10-6

7-11

11-1

10-10

10-4

7-11

11-6

11-4

11-1

8-4

10-10

10-6

10-6

7-11

18-516-11

15-9

11-11

17-5

16-6

15-6

11-11

18-1

17-9

16-7

12-7

17-0

15-9

15-9

11-11

20-020-0

20-0

15-4

20-0

20-0

20-0

15-4

20-0

20-0

20-0

16-4

20-0

20-0

20-0

15-4

– Lumber grade not available or allowable stud length is less than 7′-9″ (For 8′ wall height).a Maximum stud lengths in Table 3.20A are based on interior zone loads and assume that all studs are sheathed with a minimum sheathing material. Studs within 4′ of corners shall be sheathed on the exterior with a minimum of 3/8″ wood structural panels and on the interior with a minimum sheathing material, or stud spacings shall be multiplied by 0.85 for framing located within 4′ of corners to account for the additional end zone loding requirements. The additional bending capacity provided by the wood structural panels or reduced stud spacing is assumed to be sufficient to resist the additional end zone loading requirements.

See Footnote 1

TABLE 3.20A

MAXIMUM EXTERIOR LOADBEARING AND NON-LOADBEARING STUD LENGTHS FOR COMMON LUMBER SPECIES RESISTING INTERIOR ZONE WIND LOADS

(Fully Sheathed with a Minimum Sheathing Material)a

Three Second Gust Wind Speed (mph) 120 130 140 150
Stud
Spacing
(in.)
Species Grade 2×4 2×6 2×8 2×4 2×6 2×8 2×4 2×6 2×8 2×4 2×6 2×8
Maximum Allowable Stud Length (ft.-in.)1
12 Douglas Fir-LarchDouglas Fir-Larch

Douglas Fir-Larch

Douglas Fir-Larch

Douglas Fir-Larch

Hem-Fir

Hem-Fir

Hem-Fir

Hem-Fir

Hem-Fir

Southern Pine

Southern Pine

Southern Pine

Southern Pine

Southern Pine

Spruce-Pine-Fir

Spruce-Pine-Fir

Spruce-Pine-Fir

Spruce-Pine-Fir

Spruce-Pine-Fir

SS#1

#2

Stud

Standard

SS

#1

#2

Stud

Standard

SS

#1

#2

Stud

Standard

SS

#1

#2

Stud

Standard

13-1113-5

13-2

10-6

8-8

13-2

12-11

12-3

10-6

8-8

13-8

13-5

13-2

11-0

9-4

12-11

12-7

12-7

10-6

8-8

20-020-0

20-0

15-9

20-0

20-0

19-4

15-9

20-0

20-0

20-0

16-8

20-0

19-9

19-9

15-9

20-020-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

13-312-9

12-6

9-8

8-0

12-6

12-3

11-8

9-8

8-0

13-0

12-9

12-6

10-1

8-7

12-3

11-11

11-11

9-8

8-0

20-020-0

19-2

14-5

19-7

19-2

18-4

14-5

20-0

20-0

19-7

15-4

19-2

18-9

18-9

14-5

20-020-0

20-0

18-8

20-0

20-0

20-0

18-8

20-0

20-0

20-0

19-10

20-0

20-0

20-0

18-8

12-712-1

11-9

8-11

11-11

11-8

11-1

8-11

12-4

12-1

11-11

9-4

7-11

11-8

11-4

11-4

8-11

19-919-0

17-8

13-4

18-8

18-3

17-5

13-4

19-5

19-1

18-7

14-2

18-3

17-8

17-8

13-4

20-020-0

20-0

17-2

20-0

20-0

20-0

17-2

20-0

20-0

20-0

18-4

20-0

20-0

20-0

17-2

12-011-7

10-11

8-3

11-4

11-1

10-7

8-3

11-10

11-7

11-4

8-8

11-1

10-10

10-10

8-3

18-1117-8

16-5

12-5

17-10

17-2

16-2

12-5

18-7

18-2

17-3

13-1

17-5

16-5

16-5

12-5

20-020-0

20-0

16-0

20-0

20-0

20-0

16-0

20-0

20-0

20-0

17-0

20-0

20-0

20-0

16-0

16

Douglas Fir-LarchDouglas Fir-Larch

Douglas Fir-Larch

Douglas Fir-Larch

Douglas Fir-Larch

Hem-Fir

Hem-Fir

Hem-Fir

Hem-Fir

Hem-Fir

Southern Pine

Southern Pine

Southern Pine

Southern Pine

Southern Pine

Spruce-Pine-Fir

Spruce-Pine-Fir

Spruce-Pine-Fir

Spruce-Pine-Fir

Spruce-Pine-Fir

SS#1

#2

Stud

Standard

SS

#1

#2

Stud

Standard

SS

#1

#2

Stud

Standard

SS

#1

#2

Stud

Standard

12-812-2

11-11

9-0

12-0

11-8

11-2

9-0

12-5

12-2

12-0

9-5

8-0

11-8

11-5

11-5

9-0

19-1119-2

17-10

13-6

18-10

18-5

17-6

13-6

19-7

19-2

18-10

14-3

18-5

17-10

17-10

13-6

20-020-0

20-0

17-5

20-0

20-0

20-0

17-5

20-0

20-0

20-0

18-6

20-0

20-0

20-0

17-5

12-011-7

10-11

8-3

11-4

11-1

10-7

8-3

11-10

11-7

11-4

8-8

11-1

10-10

10-10

8-3

18-1017-7

16-5

12-5

17-10

17-2

16-2

12-5

18-6

18-2

17-3

13-1

17-5

16-5

16-5

12-5

20-020-0

20-0

16-0

20-0

20-0

20-0

16-0

20-0

20-0

20-0

17-0

20-0

20-0

20-0

16-0

11-510-10

10-1

10-10

10-6

9-11

11-3

11-0

10-10

8-0

10-7

10-1

10-1

18-016-3

15-2

11-5

17-0

15-10

14-11

11-5

17-8

17-4

15-11

12-1

16-7

15-2

15-2

11-5

20-020-0

19-6

14-9

20-0

20-0

19-3

14-9

20-0

20-0

20-0

15-8

20-0

19-6

19-6

14-9

10-1110-1

9-4

10-4

9-9

9-3

10-9

10-6

10-1

10-1

9-4

9-4

17-215-1

14-1

10-8

16-2

14-8

13-10

10-8

16-10

16-6

14-9

11-3

15-10

14-1

14-1

10-8

20-019-6

18-1

13-8

20-0

18-11

17-10

13-8

20-0

20-0

19-6

14-7

20-0

18-1

18-1

13-8

24

Douglas Fir-LarchDouglas Fir-Larch

Douglas Fir-Larch

Douglas Fir-Larch

Douglas Fir-Larch

Hem-Fir

Hem-Fir

Hem-Fir

Hem-Fir

Hem-Fir

Southern Pine

Southern Pine

Southern Pine

Southern Pine

Southern Pine

Spruce-Pine-Fir

Spruce-Pine-Fir

Spruce-Pine-Fir

Spruce-Pine-Fir

Spruce-Pine-Fir

SS#1

#2

Stud

Standard

SS

#1

#2

Stud

Standard

SS

#1

#2

Stud

Standard

SS

#1

#2

Stud

Standard

11-110-3

9-7

10-5

10-0

9-5

10-10

10-8

10-3

10-3

9-7

9-7

17-515-5

14-4

10-10

16-5

15-0

14-2

10-10

17-1

16-9

15-1

11-6

16-1

14-4

14-4

10-10

20-019-11

18-6

14-0

20-0

19-4

18-3

14-0

20-0

20-0

19-11

14-11

20-0

18-6

18-6

14-0

10-69-5

8-9

9-11

9-2

8-8

10-4

10-1

9-5

9-8

8-9

8-9

16-614-2

13-2

10-0

15-7

13-9

13-0

10-0

16-2

15-11

13-10

10-7

15-3

13-2

13-2

10-0

20-018-3

17-0

12-10

20-0

17-9

16-9

12-10

20-0

20-0

18-3

13-8

20-0

17-0

17-0

12-10

10-08-9

8-1

9-5

8-6

8-0

9-10

9-7

8-9

9-3

8-1

8-1

15-813-1

12-2

9-3

14-10

12-9

12-0

9-3

15-5

14-10

12-10

9-9

14-6

12-2

12-2

9-3

20-016-10

15-8

11-10

19-6

16-5

15-5

11-10

20-0

19-0

16-10

12-8

19-0

15-8

15-8

11-10

9-68-1

9-0

7-11

9-4

9-1

8-1

8-10

14-1012-2

11-4

8-7

14-2

11-10

11-2

8-7

14-9

13-10

11-11

9-1

13-8

11-4

11-4

8-7

19-115-8

14-7

11-0

18-8

15-3

14-4

11-0

19-5

17-8

15-8

11-9

17-8

14-7

14-7

11-0

– Lumber grade not available or allowable stud length is less than 7′-9″ (For 8′ wall height).a Maximum stud lengths in Table 3.20A are based on interior zone loads and assume that all studs are sheathed with a minimum sheathing material. Studs within 4′ of corners shall be sheathed on the exterior with a minimum of 3/8″ wood structural panels and on the interior with a minimum sheathing material, or stud spacings shall be multiplied by 0.85 for framing located within 4′ of corners to account for the additional end zone loding requirements. The additional bending capacity provided by the wood structural panels or reduced stud spacing is assumed to be sufficient to resist the additional end zone loading requirements.

See Footnote 1

stjohns2007

TABLE 3.20B

MAXIMUM EXTERIOR LOADBEARING AND NON-LOADBEARING STUD LENGTHS FOR COMMON LUMBER SPECIES RESISTING INTERIOR ZONE WIND LOADS

(Fully Sheathed with a Minimum of 3/8″ Wood Structural Panels)a

Three Second Gust Wind Speed (mph) 85 90 100 110
Stud
Spacing
(in.)
Species Grade 2×4 2×6 2×8 2×4 2×6 2×8 2×4 2×6 2×8 2×4 2×6 2×8
Maximum Allowable Stud Length (ft.-in.)1

12

Douglas Fir-LarchDouglas Fir-Larch

Douglas Fir-Larch

Douglas Fir-Larch

Douglas Fir-Larch

Hem-Fir

Hem-Fir

Hem-Fir

Hem-Fir

Hem-Fir

Southern Pine

Southern Pine

Southern Pine

Southern Pine

Southern Pine

Spruce-Pine-Fir

Spruce-Pine-Fir

Spruce-Pine-Fir

Spruce-Pine-Fir

Spruce-Pine-Fir

SS#1

#2

Stud

Standard

SS

#1

#2

Stud

Standard

SS

#1

#2

Stud

Standard

SS

#1

#2

Stud

Standard

17-716-11

16-7

15-10

14-6

16-7

16-3

15-6

15-1

14-6

17-3

16-11

16-7

15-10

15-6

16-3

15-10

15-10

15-1

14-6

20-020-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-020-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

16-1116-3

15-11

15-3

13-8

15-11

15-7

14-11

14-6

13-8

16-7

16-3

15-11

15-3

14-7

15-7

15-3

15-3

14-6

13-8

20-020-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-020-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

15-915-2

14-10

14-3

12-2

14-10

14-7

13-10

13-6

12-2

15-6

15-2

14-10

14-3

13-1

14-7

14-3

14-3

13-6

12-2

20-020-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-020-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

14-914-3

13-11

13-3

11-0

13-11

13-8

13-0

12-8

11-0

14-6

14-3

13-11

13-4

11-9

13-8

13-4

13-4

12-8

11-0

20-020-0

20-0

18-10

20-0

20-0

20-0

18-10

20-0

20-0

20-0

19-11

20-0

20-0

20-0

18-10

20-020-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

16 Douglas Fir-LarchDouglas Fir-Larch

Douglas Fir-Larch

Douglas Fir-Larch

Douglas Fir-Larch

Hem-Fir

Hem-Fir

Hem-Fir

Hem-Fir

Hem-Fir

Southern Pine

Southern Pine

Southern Pine

Southern Pine

Southern Pine

Spruce-Pine-Fir

Spruce-Pine-Fir

Spruce-Pine-Fir

Spruce-Pine-Fir

Spruce-Pine-Fir

SS#1

#2

Stud

Standard

SS

#1

#2

Stud

Standard

SS

#1

#2

Stud

Standard

SS

#1

#2

Stud

Standard

15-1115-4

15-1

14-5

12-5

15-1

14-9

14-1

13-8

12-5

15-8

15-4

15-1

14-5

13-4

14-9

14-5

14-5

13-8

12-5

20-020-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-020-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

15-414-9

14-6

13-10

11-8

14-6

14-2

13-6

13-2

11-8

15-1

14-9

14-6

13-10

12-6

14-2

13-10

13-10

13-2

11-8

20-020-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-020-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

14-413-9

13-6

12-7

10-5

13-6

13-3

12-7

12-3

10-5

14-1

13-9

13-6

12-11

11-2

13-3

12-11

12-11

12-3

10-5

20-020-0

20-0

17-11

20-0

20-0

19-10

17-11

20-0

20-0

20-0

18-11

20-0

20-0

20-0

17-11

20-020-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

13-512-11

12-8

11-4

9-5

12-8

12-5

11-10

11-4

9-5

13-2

12-11

12-8

11-11

10-1

12-5

12-1

12-1

11-4

9-5

20-020-0

19-11

16-2

19-11

19-6

18-7

16-2

20-0

20-0

19-11

17-1

19-6

19-1

19-1

16-2

20-020-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

24 Douglas Fir-LarchDouglas Fir-Larch

Douglas Fir-Larch

Douglas Fir-Larch

Douglas Fir-Larch

Hem-Fir

Hem-Fir

Hem-Fir

Hem-Fir

Hem-Fir

Southern Pine

Southern Pine

Southern Pine

Southern Pine

Southern Pine

Spruce-Pine-Fir

Spruce-Pine-Fir

Spruce-Pine-Fir

Spruce-Pine-Fir

Spruce-Pine-Fir

SS#1

#2

Stud

Standard

SS

#1

#2

Stud

Standard

SS

#1

#2

Stud

Standard

SS

#1

#2

Stud

Standard

13-1113-5

13-2

12-1

10-0

13-2

12-10

12-3

11-11

10-0

13-8

13-5

13-2

12-7

10-9

12-10

12-7

12-7

11-11

10-0

20-020-0

20-0

17-2

20-0

20-0

19-3

17-2

20-0

20-0

20-0

18-2

20-0

19-9

19-9

17-2

20-020-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

13-512-11

12-8

11-4

9-5

12-8

12-5

11-10

11-4

9-5

13-2

12-11

12-8

11-11

10-1

12-5

12-1

12-1

11-4

9-5

20-020-0

19-11

16-1

19-11

19-6

18-7

16-1

20-0

20-0

19-11

17-1

19-6

19-0

19-0

16-1

20-020-0

20-0

19-11

20-0

20-0

20-0

19-11

20-0

20-0

20-0

20-0

20-0

20-0

20-0

19-11

12-612-0

11-10

10-2

8-5

11-10

11-7

11-0

10-2

8-5

12-3

12-0

11-10

10-7

9-0

11-7

11-3

11-3

10-2

8-5

19-818-11

18-7

14-5

18-7

18-2

17-4

14-5

19-3

18-11

18-7

15-3

18-2

17-9

17-9

14-5

20-020-0

20-0

17-10

20-0

20-0

20-0

17-10

20-0

20-0

20-0

18-11

20-0

20-0

20-0

17-10

11-911-4

11-1

9-2

11-1

10-10

10-4

9-2

11-6

11-4

11-1

9-7

8-2

10-10

10-7

10-7

9-2

18-517-9

17-2

13-0

17-5

17-0

16-3

13-0

18-1

17-9

17-5

13-9

17-0

16-8

16-8

13-0

20-020-0

20-0

16-1

20-0

20-0

20-0

16-1

20-0

20-0

20-0

17-1

20-0

20-0

20-0

16-1

– Lumber grade not available or allowable stud length is less than 7′-9″ (For 8′ wall height).a Maximum stud lengths in Table 3.20B are based on interior zone loads and assume that all studs are sheathed on the exterior with a minimum of 3/8″ wood structural panels and on the interior with a minimum sheathing material. Stud spacings shall be multiplied by 0.85 for framing located within 4′ of corners to account for the additional end zone loading requirements.

See Footnote 1

TABLE 3.20B

MAXIMUM EXTERIOR LOADBEARING AND NON-LOADBEARING STUD LENGTHS FOR COMMON LUMBER SPECIES RESISTING INTERIOR ZONE WIND LOADS

(Fully Sheathed with a Minimum of 3/8″ Wood Structural Panels)a

Three Second Gust Wind Speed (mph) 120 130 140 150
Stud
Spacing
(in.)
Species Grade 2×4 2×6 2×8 2×4 2×6 2×8 2×4 2×6 2×8 2×4 2×6 2×8
Maximum Allowable Stud Length (ft.-in.)1
12 Douglas Fir-LarchDouglas Fir-Larch

Douglas Fir-Larch

Douglas Fir-Larch

Douglas Fir-Larch

Hem-Fir

Hem-Fir

Hem-Fir

Hem-Fir

Hem-Fir

Southern Pine

Southern Pine

Southern Pine

Southern Pine

Southern Pine

Spruce-Pine-Fir

Spruce-Pine-Fir

Spruce-Pine-Fir

Spruce-Pine-Fir

Spruce-Pine-Fir

SS#1

#2

Stud

Standard

SS

#1

#2

Stud

Standard

SS

#1

#2

Stud

Standard

SS

#1

#2

Stud

Standard

13-1113-5

13-2

12-1

10-0

13-2

12-11

12-3

12-0

10-0

13-8

13-5

13-2

12-7

10-9

12-11

12-7

12-7

12-0

10-0

20-020-0

20-0

17-2

20-0

20-0

19-4

17-2

20-0

20-0

20-0

18-2

20-0

19-9

19-9

17-2

20-020-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

20-0

13-312-9

12-6

11-1

9-3

12-6

12-3

11-8

11-1

9-3

13-0

12-9

12-6

11-7

9-10

12-3

11-11

11-11

11-1

9-3

20-020-0

19-7

15-9

19-7

19-2

18-4

15-9

20-0

20-0

19-7

16-8

19-2

18-9

18-9

15-9

20-020-0

20-0

19-6

20-0

20-0

20-0

19-6

20-0

20-0

20-0

20-0

20-0

20-0

20-0

19-6

12-712-1

11-11

10-3

8-6

11-11

11-8

11-1

10-3

8-6

12-4

12-1

11-11

10-9

9-1

11-8

11-4

11-4

10-3

8-6

19-919-1

18-8

14-7

18-8

18-3

17-5

14-7

19-5

19-1

18-8

15-5

18-3

17-10

17-10

14-7

20-020-0

20-0

18-0

20-0

20-0

20-0

18-0

20-0

20-0

20-0

19-2

20-0

20-0

20-0

18-0

12-011-7

11-4

9-6

7-11

11-4

11-1

10-7

9-6

7-11

11-10

11-7

11-4

10-0

8-6

11-1

10-10

10-10

9-6

7-11

18-1118-2

17-10

13-6

17-10

17-5

16-8

13-6

18-7

18-2

17-10

14-4

17-5

17-1

17-1

13-6

20-020-0

20-0

16-8

20-0

20-0

20-0

16-8

20-0

20-0

20-0

17-9

20-0

20-0

20-0

16-8

16 Douglas Fir-LarchDouglas Fir-Larch

Douglas Fir-Larch

Douglas Fir-Larch

Douglas Fir-Larch

Hem-Fir

Hem-Fir

Hem-Fir

Hem-Fir

Hem-Fir

Southern Pine

Southern Pine

Southern Pine

Southern Pine

Southern Pine

Spruce-Pine-Fir

Spruce-Pine-Fir

Spruce-Pine-Fir

Spruce-Pine-Fir

Spruce-Pine-Fir

SS#1

#2

Stud

Standard

SS

#1

#2

Stud

Standard

SS

#1

#2

Stud

Standard

SS

#1

#2

Stud

Standard

12-812-2

12-0

10-4

8-7

12-0

11-8

11-2

10-4

8-7

12-5

12-2

12-0

10-10

9-3

11-8

11-5

11-5

10-4

8-7

19-1119-2

18-10

14-9

18-10

18-5

17-6

14-9

19-7

19-2

18-10

15-7

18-5

18-0

18-0

14-9

20-020-0

20-0

18-2

20-0

20-0

20-0

18-2

20-0

20-0

20-0

19-4

20-0

20-0

20-0

18-2

12-011-7

11-4

9-6

7-11

11-4

11-1

10-7

9-6

7-11

11-10

11-7

11-4

10-0

8-5

11-1

10-10

10-10

9-6

7-11

18-1018-2

17-10

13-6

17-10

17-5

16-8

13-6

18-6

18-2

17-10

14-3

17-5

17-1

17-1

13-6

20-020-0

20-0

16-8

20-0

20-0

20-0

16-8

20-0

20-0

20-0

17-9

20-0

20-0

20-0

16-8

11-511-0

10-10

8-9

10-10

10-7

10-1

8-9

11-3

11-0

10-10

9-2

7-10

10-7

10-4

10-4

8-9

18-017-4

16-6

12-6

17-0

16-7

15-10

12-6

17-8

17-4

17-0

13-2

16-7

16-3

16-3

12-6

20-020-0

20-0

15-5

20-0

20-0

20-0

15-5

20-0

20-0

20-0

16-5

20-0

20-0

20-0

15-5

10-1110-6

10-4

8-2

10-4

10-1

9-7

8-2

10-9

10-6

10-4

8-7

10-1

9-10

9-10

8-2

17-216-6

15-4

11-7

16-2

15-10

15-1

11-7

16-10

16-6

16-1

12-3

15-10

15-4

15-4

11-7

20-020-0

18-11

14-4

20-0

19-10

18-8

14-4

20-0

20-0

20-0

15-3

20-0

18-11

18-11

14-4

24 Douglas Fir-LarchDouglas Fir-Larch

Douglas Fir-Larch

Douglas Fir-Larch

Douglas Fir-Larch

Hem-Fir

Hem-Fir

Hem-Fir

Hem-Fir

Hem-Fir

Southern Pine

Southern Pine

Southern Pine

Southern Pine

Southern Pine

Spruce-Pine-Fir

Spruce-Pine-Fir

Spruce-Pine-Fir

Spruce-Pine-Fir

Spruce-Pine-Fir

SS#1

#2

Stud

Standard

SS

#1

#2

Stud

Standard

SS

#1

#2

Stud

Standard

SS

#1

#2

Stud

Standard

11-110-8

10-5

8-4

10-5

10-3

9-9

8-4

10-10

10-8

10-5

8-9

10-3

10-0

10-0

8-4

17-516-9

15-8

11-10

16-5

16-1

15-4

11-10

17-1

16-9

16-5

12-6

16-1

15-8

15-8

11-10

20-020-0

19-4

14-8

20-0

20-0

19-1

14-8

20-0

20-0

20-0

15-7

20-0

19-4

19-4

14-8

10-610-1

9-11

9-11

9-8

9-3

10-4

10-1

9-11

8-0

9-8

9-6

9-6

16-615-5

14-4

10-10

15-7

15-0

14-2

10-10

16-2

15-11

15-1

11-6

15-3

14-4

14-4

10-10

20-019-1

17-9

13-5

20-0

18-7

17-6

13-5

20-0

20-0

19-1

14-4

20-0

17-9

17-9

13-5

10-09-7

9-4

9-5

9-3

8-10

9-10

9-7

9-5

9-3

9-0

9-0

15-814-3

13-3

10-0

14-10

13-10

13-1

10-0

15-5

15-1

14-0

10-7

14-6

13-3

13-3

10-0

20-017-8

16-5

12-5

19-6

17-2

16-2

12-5

20-0

19-11

17-8

13-2

19-1

16-5

16-5

12-5

9-69-2

8-8

9-0

8-10

8-5

9-4

9-2

9-0

8-10

8-7

8-7

15-013-3

12-4

9-4

14-2

12-11

12-2

9-4

14-9

14-5

13-0

9-10

13-10

12-4

12-4

9-4

19-916-5

15-3

11-6

18-8

15-11

15-0

11-6

19-5

18-6

16-5

12-3

18-3

15-3

15-3

11-6

– Lumber grade not available or allowable stud length is less than 7′-9″ (For 8′ wall height).a Maximum stud lengths in Table 3.20B are based on interior zone loads and assume that all studs are sheathed on the exterior with a minimum of 3/8″ wood structural panels and on the interior with a minimum sheathing material. Stud spacings shall be multiplied by 0.85 for framing located within 4′ of corners to account for the additional end zone loading requirements.

See Footnote 1

Footnotes to Tables 3.20A&B

1 Maximum stud lengths in Tables 3.20A&B are based on wind loads. For dead and live loads, stud lengths shall be limited to the requirements in the following table:

2×3 2×4 2×5 2×6 2×8
Maximum Unsupported Stud Length (ft.)
10 10 10 10
Loadbearing Studs Supporting: Maximum Stud Spacing (in. o.c.)
Roof & Ceiling Only 1 Floor Only

Roof, Ceiling & 1 Floor

2 Floors Only

Roof, Ceiling & 2 Floors

2424

16

16

2424

16

16

2424

24

24

16

2424

24

24

24

stjohns2007 Maximum Unsupported Stud Length (ft.)
Non-loadbearing Studs 10 14 16 20 20
Maximum Stud Spacing (in. o.c.)
16 24 24 24 2


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