FrankWoeste

From the Don Bender news story: "One fairly recent development in wood and WPC deckboards is "hidden fasteners" that fit in a slot on the side of each board. Great idea right? You don't see the fastener, and the slot allows the board to slip so that thermal expansion and shrinkage won't cause the boards to buckle. The problem is that since the fasteners allow slip, the deck diaphragm has almost no stiffness from side-to-side. This means that the deck substructure must provide nearly all of the resistance to lateral loads. This can result in a complicated design that should be performed by a registered design professional."

"Researchers found that the loads from people can exceed those of the most severe earthquakes and hurricanes." http://www.djc.com/news/co/12077068.htm ... 1445724689

Important details by SBCA (2015) for connecting residential deck ledgers to floor trusses. Also, resource for inspecting residential deck ledger connection to existing structure. http://www.sbcindustry.com/system/files ... ledger.pdf

AWC Deck Design Guide based on the 2012 IRC now available: http://www.awc.org/publications/DCA/DCA6/DCA6-12.pdf Among other sections being updated, post and footing sizes expanded.

I suspect that a couple of forum members have seen residential drywall ceiling cracks perpendicular to the framing span and at drywall seams/joints between panels. The cracks are naturally straight and typically long. The following publication addresses the cause and unpredictable nature of the problem: http://www.kenilworth.com/publications/ ... es/94.html Comments are welcome. Frank Woeste, P. E. Professor Emeritus Virginia Tech University

I am aware of the same issue in one area of Virginia. The stair stringer attachment detail puts the nails in "withdrawal." A smooth shank nail, exposed to weather, has 1/4 of the withdrawal strength of a nail connection installed in dry lumber and remains dry in-service. Unrelated to this post, I just noticed that the new JLC book on decks and porches is 50% off: https://m1.buysub.com/webapp/wcs/stores ... yId=278345 I purchased (too soon) two copies at $40 each as it contains most of our Virginia Tech research work on decks. The table of contents is attached for your convenience. Download Attachment: Deck Book Table of Contents.pdf 37.75 KB

Chad: Thank you for the kind remarks about the post. More deck problems today after a funeral (link below). Frank Woeste, Professor Emeritus, Virginia Tech http://www.necn.com/09/16/10/6-injured- ... eedID=4206

Re the balcony collapse last weekend, this post raises some design questions. Referring to this document: http://www.wwpinstitute.org/mainpages/d ... un1807.pdf do you think that cantilevered balconies fall into the UC3A category or the UC4B use category (or higher)? UC3A — Wood and wood based materials used in exterior construction that are coated and not in contact with the ground. Such products may be exposed to the full effects of weather, but are in vertical exterior walls or other types of construction that allows water to quickly drain from the surface. UC4B — Wood and wood based materials used in contact with the ground either in severe environments, such as horticultural sites, in climates with a high potential for deterioration, in critically important components. Referring to the first table in the wwpinstitute.org document, UC4B calls for about three times (3x) the chemical retention that is required for a UC3A use. Questions for discussion. Should cantilevered balconies be permitted to use “Above Groundâ€

Turns out he already has. See June '09 JLC, p19. BTW, he uses the term 'cantilever' when the joist extends out beyond the foundation. (neener neener neener!) Actually, there is a technical difference. In the case of a cantilever structural model, the "slope of the elastic curve" at the support point is zero (no rotation). In the case of a beam overhang, the slope of the elastic curve at the bearing location next to the overhang is, in general, non-zero. At the bearing location, the rotation of the beam or (elastic curve) can be counterclockwise, zero, or clockwise depending upon the loads on the entire beam. The term cantilever seems to convey the issue easier when talking about or writing about a deck being attached to one.

This JLC Q&A addresses some of the issues: Download Attachment: JLC Attaching Deck Ledgers to I-Joist Cantilevers June 2009.pdf 98.21 KB

More deck problems in GA: http://www.ajc.com/metro/content/metro/ ... lapse.html

Bain: Yes, water infiltration is an issue. Also, since the brick veneer isn't allowed to support anything other than its own weight, the bolted connection would have a large "gap" between the two wooden members of the connection (house band and deck ledger). The "gap" would be composed of the sheathing thickness, an air space, and the width of the brick. The presence of the "gap", whatever it adds up to be, greatly reduces the structural strength and stiffness of the bolted connection. We tested the case where the "gap" was only 15/32" (wall sheathing) and the results of that case are tabulated in the ledger table of DCA6. It's worth noting that tabulated bolt shear values published for years in the NDS and other wood design books are based on the assumption of no gap between the members. Good question. Frank

gtblum: They were showing a Simpson Strong-Tie fastener and you can contact them for specific design information. If you are interested in the general subject of deck ledger connection design including connection to an Engineered Wood Product (EWP) Rimboard that is bearing on a sill plate, then you can review this document: http://awc.org/Publications/DCA/DCA6/DCA6.pdf Frank Woeste Professor Emeritus Virginia Tech University Blacksburg

Here's the link to the video: http://www.cbsnews.com/video/watch/?id=5109091n

Misinformation about deck construction abounds. Perhaps you can talk about the importance of the ledger board attachment to the home. What is the correct way to attach the ledger board to the home? Terry: I suggest you take a look at Figure 14, page 11 of this document for connection to a solid-sawn house band bearing on a sill plate: http://awc.org/Publications/DCA/DCA6/DCA6.pdf DCA6 is a wood industry document. Frank

Bain and Kurt: Thank you for the warm welcome to the discussion. Attached is a research report that combined the PPT Southern Pine ledger testing results with the PPT Hem-Fir ledger testing results. It was interesting to learn that 1/2" thru bolts were about twice as strong as 1/2" lag screws in this application (ledger connected to SPF house band without stacked washers). Download Attachment: WDF Deck Ledgers Aug. 2006.pdf 372.43 KB Frank

Kurt: I realize your question cites the 2006 IRC. If you are still looking for ledger connection design data that is ready for adoption by states and jurisdictions, you can find a table in the 2009 IRC, page 113. The table caption is: TABLE R502.2.2.1 FASTENER SPACING FOR A SOUTHERN PINE OR HEM-FIR DECK LEDGER AND A 2-INCH NOMINAL SOLID-SAWN SPRUCE-PINE-FIR BAND JOISTc, f, g If you are interested in ledger connection design data for connecting to Engineered Wood Product (EWP) rim boards, you can find that data in Table 5 at: http://awc.org/Publications/DCA/DCA6/DCA6.pdf Frank Woeste Professor Emeritus Virginia Tech University Blacksburg

We have a new publication that adds to what is in the deck inspection manual. A summary of the five (new) papers follows. You can order it by going to the attached file. If you want a copy of a paper with my name on it, please e-mail me and I'll send a copy. Thanks, Frank Woeste e-mail:fwoeste@vt.edu Wood Design Focus Editorial This issue of Wood Design Focus deals with deck design and construction. One only needs to do a web search on “deck collapseâ€