APPENDIX C
1. Wood preservatives for ground contact. The following Table lists common pressure-preservative treatments and retention levels, in pounds per cubic foot, for sawn lumber in ground contact – based on the American Wood Protection Association's Book of Standards.
Table C–1
PRESERVATIVE TREATMENTS AND RETENTION LEVELS FOR
1NR = treatment not recommended.
2. Sources of design values. The sources of the design values in Appendix B are as follows:
Table 1 – Minimum footing sizes: The Building Inspectors Association of Southeast Wisconsin, December 2014.
Table 2 – Maximum post heights: Typical Deck Details,
Based on the 2009 International Residential Code, Fairfax County, Virginia, July 2013.
Tables 3A and 3B – Maximum beam spans: Design for Code Acceptance 6, American Wood Council, May 2013.
Table 4 – Maximum joist spans: Design for Code Acceptance 6 (DCA 6), American Wood Council, May 2013; except for the 2x6 values, which are from the Building Inspectors Association of Southeast Wisconsin, December 2014.
Table 5 – Minimum joist-hanger download capacity: Design for Code Acceptance 6, American Wood Council, May 2013; except for the 2x6 values, which are repeated from the 2x8 values.
Table 6 – Ledger-board-fastener spacing: Design for Code Acceptance 6, American Wood Council, May 2013.
Figure 29 – Stringer span length, and Table 7 – Minimum tread sizes:
Design for Code Acceptance 6, American Wood Council, May 2013.
Table C–2 – Maximum joist spans for redwood, western cedars, ponderosa pine, and red pine: Design for Code Acceptance 6, American Wood Council, May 2013; except for the 2x6 values, which are from the Building Inspectors Association of Southeast Wisconsin, December 2014.
Table C–3 – Trimmer joist download capacity: Design for Code Acceptance 6, American Wood Council, May 2013.
3. Joist spans for alternate wood species. The following Table lists maximum joist-span lengths for redwood, western cedars, ponderosa pine, and red pine.
Table C–2
MAXIMUM JOIST-SPAN LENGTH1 FOR REDWOOD,
1Spans are based on 40 psf live load, 10 psf dead load, normal loading duration, wet service conditions and deflections of Ä=L/360 for main span and L/180 for overhang with a 220-lb. point load.
2Design values based on northern species with no incising assumed.
4. Alternate beam and joist spans. The table on the following two pages lists alternate beam and joist spans and corresponding footing sizes from the Southeast Wisconsin Building Inspectors Association that can be used instead of the values in Appendix B
.
- See PDF for table 
Notes:
1. Joist Length (JL) is Joist Span (LJ) plus any cantilever at the beam that is being sized.
2. Incising assumed for refractory species Douglas Fir-Larch.
3. All footing sizes above are base diameters (in inches) and are listed for THREE SOIL CAPACITIES. Soil capacity is based on the requirements of State of Wisconsin SPS 321.15 (3).4
4.
For square footings, insert the diameter (d) into the following formula:√((d/2)2 x p). This number will give you the square dimension and shall be rounded up to the nearest inch.
- See PDF for table
5. Framing around a chimney or bay window. All members at a chimney or bay window must be framed in accordance with Figure C–1. Headers may span a maximum of 6'-0”. Where a chimney or bay window is wider than 6'-0”, one or more 6x6 posts may be added to reduce header spans to less than 6'-0”. In such cases, the post footing must meet the requirements in section 2 of Appendix B. Plan submittal and approval is required for headers with a span length greater than
6'-0”
. Headers must be located no more than 3'-0” from the end of the trimmer joist.
Triple trimmer joists are required on each side of the header if joist spacing is 12” or 16” on center or if the trimmer joist span exceeds 8'-6”; otherwise, double trimmer joists are permitted. Trimmer joists may bear on the beam and extend past the beam centerline up to LJ/4 as shown in Figures 5 and 7 in Appendix B, or the trimmer joist may attach to the side of the beam with joist hangers as shown in Figure 6 in Appendix B. Joist hangers must each have a minimum download capacity in accordance with Table C–3. Bolts or lag screws used to attach the hanger to the ledger must fully extend through the ledger into the 2-inch nominal lumber band joist (1 1/2“ actual) or the EWP rim board. See Figure 15 in Appendix B for fastener spacing, and edge and end distances. Otherwise a free-standing deck is required.
Figure C–1
DETAIL FOR FRAMING AROUND A CHIMNEY OR BAY WINDOW
Table C–3
6. Attachment of ledger boards to metal-plate-connected wood floor trusses. The research report on the following pages shows acceptable methods for attaching a ledger board to a metal-plate-connected wood-floor-truss system.
Attachment of Residential Deck Ledger to
Metal Plate Connected Wood Truss Floor System
SRR No. 1408-01
Prepared for SBCA
Report Written by:
Jim Vogt, P.E.
October 1, 2014
Table of Contents
Introduction 264
Key Definitions 264
Background 264
Application 265
Installation 265
Findings 272
References and Substantiating Data 272
Introduction:
This research report provides construction details for residential deck ledger attachment to metal plate connected wood truss floor systems. The applicable codes and standards follow the 2009 and 2012 International Building Code (IBC) and the 2009 and 2012 International Residential Code (
IRC). Proper attachment of the deck ledger to the house is critical for ensuring that an “attached” deck is safely and securely supported at this location. This report provides details for attaching a 2” nominal lumber deck ledger to residential floor systems constructed with metal plate connected wood (MPCW) floor trusses.
Key Definitions:
Deck Ledger – A horizontal lumber beam attached to an existing wall and used to tie in construction elements such as porch roofs and decks. A deck ledger is installed as part of the deck frame construction and supports one end of the deck joists.
Truss – An engineered structural component, assembled from wood members, metal connector plates and other mechanical fasteners, designed to carry its own weight and superimposed design loads. The truss members form a semi-rigid structural framework and are assembled such that the members form triangles.
Wood Structural Panel (WSP) – A panel manufactured from wood veneers, strands or wafers or a combination of veneer and wood strands or wafers bonded together with waterproof synthetic resins or other suitable bonding systems. Examples include: plywood, Oriented Strand Board (OSB), waferboard and composite panels.
Background:
The 2009 and 2012 IRC include prescriptive provisions for attaching a 2” nominal lumber deck ledger to a 2” nominal lumber band joist bearing directly on a sill plate or wall plate using 1/2”-diameter bolts or lag screws. AF&PA's American Wood Council, in cooperation with the International Code Council, has also developed Design for Code Acceptance No. 6 (DCA6) – Prescriptive Residential Deck Construction Guide, available at awc.org.
The prescriptive provisions for the deck ledger connection to the band joist in the IRC and DCA6 are based on the results from a series of ultimate load tests conducted at Virginia Polytechnic Institute and State University (VT) Department of Wood Science and Forest Products, and Washington State University (WSU) Wood Materials and Engineering Laboratory. This testing evaluated the capacity 2” nominal pressure-preservative-treated (PPT) Hem-Fir (HF) and Southern Pine (SP) ledgers attached to either 2” nominal Spruce-Pine-Fir (SPF) or 1” net Douglas-Fir (DF) laminated veneer lumber (LVL) band joists, through 15/32”-thick oriented strand board (OSB) sheathing, with 1/2”-diameter hot-dipped galvanized (HDG) bolts or lag screws, meeting the requirements of ANSI/ASME Standard B18.2.1.
The deck ledger assemblies evaluated at VT and WSU were deemed to represent commonly accepted means of connecting deck ledgers to band joints that cannot be evaluated using the provisions of the National Design Specification® for Wood Construction (NDS®) because:
1.
The ledger is not in direct contact with the band joist (i.e., separated by 15/32” OSB sheathing).
2.
The minimum required penetration depth of four diameters (4D) is not met when using 1/2”-diameter lag screws into an 11/2”-thick band joist.
Application:
The details and fastener spacing tables provided in this report for connecting a 2” nominal lumber deck ledger to a residential floor system constructed with MPCW trusses use a single shear reference lateral design value, Z, of 710 lbs. for a 1/2”-diameter bolt and 375 lbs. for a 1/2” x 6” lag screw. These lateral design values were developed from the VT and WSU testing, and assume the fasteners are installed in accordance with the NDS requirements for clearance holes, lead holes, edge distance and end distance.
Detail 1 includes construction information for attaching 2” nominal lumber deck ledgers to the ends of MPCW floor trusses spaced no more than 24” o.c. Table 1 provides the maximum on-center spacing for each 1/2”-diameter bolt or 1/2” x 6” lag screw used to attach the ledger to the floor truss system for deck joist spans up to 18', assuming a design deck load of 40 psf live load (or 40 psf snow load) and 10 psf dead load. Table 2 includes similar information as Table 1, except for a design deck load of 60 psf live load (or 60 psf snow load) and 10 psf dead load.
Detail 2 includes construction information for attaching 2” nominal lumber deck ledgers to the side of a MPCW floor ladder frame with 4x4 vertical webs spaced no more than 16” o.c. provides the maximum on-center spacing for each 1/2”-diameter bolt and 1/2” x 6” lag screw used to attach the ledger to the ladder frame for deck joist spans up to 18', assuming a design deck load of 40 psf live load (or 40 psf snow load) and 10 psf dead load. Table 4 includes similar information as Table 3Detail 3, except for a design deck load of 60 psf live load (or 60 psf snow load) and 10 psf dead load.
Detail 3 includes deck lateral load connection options capable of resisting the 1500 lbf lateral load requirement specified in 2009 and 2012 IRC Section 507.
Support of concentrated loads from deck beams of girders are beyond the scope of this report. Deck ledgers shall not be supported on stone or masonry veneer.
Installation:
The following is a summary of the minimum requirements and limitations for installing a 2” nominal lumber deck ledger with residential floor systems constructed with MPCW floor trusses.
1.
Ledger must be 2x10 or 2x12 PPT or code-approved decay-resistant lumber with a specific gravity, G > 0.43. Ledger shall be identified by the grade mark of, or certificate of inspection issued by, an approved lumber grading or inspection bureau or agency. PPT material must be pressure-treated with an approved process in accordance with American Wood Protection Association standards
2. Install ledger directly over wood structural sheathing (15/
32” maximum thickness) fastened to the wall per the building code.
3. Attach ledger through wood structural sheathing into 2-ply 2x4 truss end vertical, 4x4 vertical web or key-block with 1/2” x 6” lag screws or 1/2”-diameter bolts with washers and nuts.
3.1
Only one (1) fastener into each truss member or key-block.
3.2 Install each fastener through the centerline of the truss member or key-block and position so as not to interfere with bottom and top chord joints and connector plates. Refer to Detail 1 and Detail 2 for spacing requirements
3.3 Lag screws and bolts shall be installed according to 2005 NDS requirements. A ”test” installation is recommended before drilling the lead holes, to ensure that the lead holes are neither too small nor too large.
1/2” x 6” lag screws:
Lead holes for the threaded portion shall be 5/16”
.
Clearance holes shall be 1/2” and the same depth of penetration as the length of unthreaded shank.
1/2” -diameter bolts:
Holes shall be a minimum of 17/32” to a maximum of 9/16”.
All fasteners used with PPT wood shall be hot-dip zinc-coated galvanized steel, stainless steel, silicon bronze, or copper. Fasteners to be hot-dipped galvanized shall meet the requirements of ASTM A153 – Standard Specification for Zinc Coating (Hot-Dip) on Iron and Steel Hardware, Class D, for fasteners 3/8” diameter and smaller or Class C for fasteners with diameters over
3/8”. Lag screws, bolts, nuts and washers are permitted to be mechanically deposited zinc-coated steel with coating weights in accordance with ASTM B695, Class 55, minimum.
