Simplified Wall Bracing

Transcription

1 Is it that simple? Simplified Wall Bracing Keep it Simple 1 2 Goal Offer the majority of the country an easy approach as a subset of the classic method. Simplified Wall Bracing Cannot mix simplified with classic 115 mph wind Simple houses = simple solutions Simple solutions = less flexibility 3 4 1

2 Simplified Wall Bracing Topics Prerequisites Methodology and materials Bracing units Bracing distribution Classic wall bracing carry-overs and comparisons Prerequisites Minimum Building Conditions 5 6 Prerequisites R Maximum of 3 stories above a solid foundation or basement. Prerequisites R Floors may not cantilever more than 24 beyond the foundation or bearing wall

3 Prerequisites R Wall heights cannot exceed 10. Prerequisites R Eave to ridge height cannot exceed 15. bigger sail area 9 10 Prerequisites R Gypsum board min. ½ or equivalent (e.g., wood paneling) on interior side of bracing. Prerequisites R Wind speed 130 mph, in Exposure B & C. < 130 mph

4 Prerequisites R Seismic Design Category A, B or C (no townhouses in SDC C). Prerequisites R townhouses Cripple walls and wood framed walls below the first floor: Prohibited in two-story Permitted in one-story 14 Quiz Question The maximum height of a wall when using Simplified Wall Bracing is: 9 feet 10 feet 12 feet 15 feet True or False: An unfinished detached garage can be braced using Simplified Wall Bracing. Quiz Question False: An unfinished garage cannot be constructed unless there is gypsum board or equivalent on the opposite side of all bracing

5 Rectangle Topics R Methodology & Materials Circumscribed rectangle Projections Open structures Size of the circumscribed rectangle Circumscribed Rectangle Circumscribed Rectangle R Draw a rectangle around the outside of the structure. Sunroom 1 st floor Circumscribe around all offsets and projections, including sunrooms and attached garages. Garage 19 Circumscribed Rectangle R Don t include Open structures: porches, decks, carports Chimneys Deck 1 st floor Carport Porch 20 5

6 Max 60 feet 20 12/31/2015 Circumscribed Rectangle R Circumscribed Rectangle R Rectangles may be different for each floor. 2 nd floor 11 st st floor Rectangle can also apply to a new addition to an existing house. Addition Existing House Circumscribed Rectangle R Circumscribed Rectangle R Maximum length of either side of the rectangle is. Max 60 feet 1 st floor 1 st floor Maximum ratio: long side = 3:1 short side

7 Circumscribed Rectangle R Example: 50 x Sheathing Materials R '-0" 36'-0" 10'-4" 3'-0" 3'-0" 14'-0" 10'-0" 2'-8" 3'-0" 3'-0" 3'-6" 5'-0" 3'-5" 2'-0" 4'-9" BREAKFAST 15'-4" FAMILY RM KITCHEN GARAGE 13'-6" 28'-0" 9'-6" 22'-0" Min. 3 / 8 OSB or plywood LIVING RM 12'-8" 5'-1" DINING RM 4'-0" Min. 1 / 2 structural fiberboard 2'-4" 2'-4" Sheathing Materials R Cannot mix OSB and structural fiberboard on the same house. Quiz Question True or False: The circumscribed rectangle below is correctly drawn. Deck 1 st floor Carport Porch False: Open structures, such as carports are not included in the circumscribed rectangle

8 Quiz Question Which is not a bracing material for Simplified Wall Bracing? Structural fiberboard Plywood OSB Gypsum board Bracing Units 3 or Bracing Units R A Bracing Unit (BU) must be: Full height sheathing without openings No vertical or horizontal offsets Bracing Units R BU length depends on application: Fully sheathed (3 BUs) Intermittent (4 BUs) OSB SFB

9 Bracing Units R No mixing of materials or applications Fully sheathed (3 BUs) Intermittent (4 BUs) OSB Multiple Bracing Units R Multiple bracing units: Wall panel lengths longer than the minimum length full credit Wall panel lengths less than the minimum length no credit SFB Multiple Bracing Units R Wall panel lengths longer than the minimum length full credit # B.U. = Actual length 3 (or 4 ) Multiple Bracing Units R Actual total number of BUs Section = 4.33 BU Section 2: <1.00 Therefore = 0 BU BU 1.3 BU 2 BU 1.8 BU Actual BUs = 6.1 Calculate each side of the rectangle independently

10 Required Number of BUs R Length of long side defines the # BUs on the short sides and vice versa More wall bracing required on short side Bigger sail area of long side Required Number of BUs R Tabular value of required BUs: Number applies to each side of rectangle Round rectangle size up to next unit of 10 No interpolation allowed Required Number of BUs R Example: 11.6 Required Number of BUs R Rectangle: 50 x 50 x 8'-0" 36'-0" 10'-4" 3'-0" 3'-0" 14'-0" 10'-0" 5'-0" 3'-5" 9'-6" 22'-0" 3'-0" 3'-0" 2'-8" 3'-6" 2'-0" 4'-9" BREAKFAST 15'-4" FAMILY RM KITCHEN GARAGE 13'-6" 28'-0" 12'-8" 5'-1" LIVING RM DINING RM 2'-4" 2'-4" 4'-0" 39 5 BUs on each long side, 6 BUs on each short sides 40 10

11 Left Right Left Right 12/31/2015 Required Number of BUs R Facing side of the rectangle Top Required Number of BUs R Partially exposed and not-exposed wall segments may also apply to a side of the rectangle Bottom 41 Partially exposed wall segment Not-exposed wall segment 42 Special Wall Construction CS-PF, Figure R Special wall construction: CS-PF Contributes 0.5 BU per panel Permitted only when fully sheathing CS-PF, PFH, PFG, CS-G

12 PFH, Figure R Special wall construction: PFH Contributes 1.0 BU per panel Permitted in all sheathing applications PFG, Figure R Special wall construction: PFG Contributes 0.75 BU per panel Permitted in all sheathing applications CS-G, Table R Special wall construction: CS-G Contributes 0.5 BU per panel Permitted only when sheathing is placed over entire structure Quiz Question How many bracing units are on the first floor front wall of the house below? =

13 Quiz Question Quiz Question How many bracing units are required on the long side of the rectangle below? First of two-story with 15 eave-to-ridge height First of two-story with 15 eave-to-ridge height Quiz Question Match the portal frame with the number of equivalent bracing units. Bracing Unit Distribution PFH 1.0 PFG 0.5 Three Rules CS-PF

14 Left 12/31/2015 Distribution Rules R BU shall be placed on the perimeter of the building and begin within 12 of all wall corners. Distribution Rules R BUs shall be 20 apart edge to edge Left No bracing on the inside of the house!!! Distribution Rules R Wall segments > 8 long must have at least one BU. 8 Quiz Question True or False: A wall with a length of 8 feet is permitted to have no bracing units. True Left Conversely, wall segments 8 long do not require a BU

15 Classic Wall Bracing Carry-overs Classic Wall Bracing Carry-overs and Comparison Bracing connections at roof construction. Masonry stem wall reinforcement Comparison Nailing Precision Criteria Classic Wall Simplified Wall Bracing Bracing Wind < 110 mph 90 mph Methodology Braced wall lines Circumscribed rectangle Required bracing Minimum length of Minimum number of bracing (feet) bracing units 8 materials, 14 Methods and 2 materials, 4 classic methods (4 materials narrow methods narrow) Maximum size house Unlimited x Corner/End of BWL Return panel or CS/fully sheathed 800 lb hold-down None Maximum wall ht

16 90 mph, Exp B, :12 Rectangle = 40 x 24 9 CEILING, CONTINUOUSLY SHEATHED WITH OSB Determine if house complies 8:12 eave ht = Compare Classic and Simplified Rear wall of house: x Classic method Bracing required 4.1 x.95 x.94 = 3.7 Simplified method Bracing required 2 3 each = 6 16

17 CSPF0.5 CSPF CSPF0.5 CSPF

18 B.U.s 7 B.U.s 12/31/ Compare Classic and Simplified B C 2.8 A D 2 5 B.U.s B.U.s CSPF0.5 CSPF Required by Classic Method Back = 14.8' Front = 12' Left = 19.7' Right = 29.1' Required by Simplified Method Back: 5x3' = 15' Front: 5x3' = 15' Left: 7x3' = 21' Right: 7x3' = 21' 70 Don t be overwhelmed