If it is hanging in space and didn’t contact the beam, that fastener would be under-driven going into the beam. They may have an apprentice running over the deck and pounding any heads down.
Because even an overdriven 6d isn’t as long as a 8d, even an under driven one. A 6d that measures as long as an 8d would fall out. Also, pretty much every time I’ve seen a 6d, they’re smooth shank and not ring shank. I’ve also seen staples, but that’s pretty much gone any more as all the homes that had them have been re-roofed in the last couple years.
Objective 3rd party. Grok. I pasted this thread over there…
Your point about evaluating whether a nail is under-driven or over-driven based on the appearance of a “shiner” (a nail that misses the truss and protrudes into the roof galley) is insightful, and I agree that a shiner complicates the assessment. Let’s break it down:
Shiner Context: A shiner occurs when a nail misses the roof truss entirely or partially, penetrating only the OSB (oriented strand board) and protruding into the space below (the roof galley). Because the nail doesn’t engage the denser truss material, it encounters less resistance, requiring less driving force to pass through the OSB. This makes it tricky to judge the driving force applied based solely on the shiner’s appearance. Over-Driven vs. Under-Driven:
Over-Driven: A nail is over-driven when excessive force embeds the nail head too deeply into the OSB, potentially crushing the material and reducing its holding strength. Building codes (e.g., IRC or APA guidelines) typically require the nail head to be flush or slightly below the OSB surface without damaging it. For a shiner, the nail may appear deeply driven because it only passed through the OSB, not because excessive force was applied. Thus, as you noted, a shiner’s protrusion doesn’t necessarily indicate over-driving, as the nail didn’t meet the resistance of the truss. Under-Driven: A nail is under-driven if the head sits above the OSB surface, reducing its holding power and risking uplift failure. A shiner could theoretically be under-driven if it didn’t fully penetrate the OSB, but this is less common since OSB offers minimal resistance compared to a truss. Why Shiners Confound Assessment: The energy applied to a nail hitting a truss versus one missing it differs significantly. When a nail hits a truss, the denser wood absorbs more energy, requiring proper calibration of tools (e.g., pneumatic nailers) to achieve flush driving. A shiner, lacking this resistance, may be driven deeper with the same energy, creating a misleading impression of over-driving. Conversely, a shiner that’s not fully through the OSB might suggest under-driving, but this could simply reflect improper aim rather than insufficient force.
Practical Implications:
Inspection Challenges: Inspectors or builders can’t reliably use shiner depth to judge driving force. Instead, they should focus on nails that hit the truss, checking if heads are flush or slightly embedded without fracturing the OSB. Fixing Shiners: Shiners should be removed or supplemented with properly driven nails into the truss to meet code requirements (e.g., 6" o.c. edge nailing, 12" o.c. field per typical IRC specs). Over-driving into the truss after a shiner is corrected can be assessed by checking OSB surface damage. Tool Calibration: If shiners are common, it may indicate misaligned nailing or improper nailer pressure. Adjust the tool to account for truss resistance, not OSB alone.
Your Argument’s Strength: You’re correct that a shiner’s appearance (e.g., how far it protrudes) doesn’t directly indicate over-driving or under-driving, as the lack of truss engagement changes the energy dynamics. This is a solid point in a discussion, especially if someone’s trying to claim over-driving based solely on shiner depth.
Not really true. Large Language models aren’t programmed beyond how to learn. They learn by what they are fed, which is essentially everything. Vast neural networks start to look like magic after that. Your brain is a vast neural network by the way.
AI can discover complex patterns that we humans might not notice.
Through training on vast datasets, AI can exhibit behaviors or knowledge that its creators didn’t directly program.
Advanced models can generate creative outputs (e.g., text, images) that surpass the capabilities of any person or group of developers.
However smart you think it is, you’re not thinking big enough if you think a bunch of California egg heads coded any specific response to any query.
Exactly. If someone puts BS in, it’s gonna spit BS out. It comes across like it’s an authority, even when it doesn’t know what it’s talking about. I had to teach Grok about the 2020 2023 FBC Residential regarding Chapter 803.
If a nail does not meet the resistance of the rafter, it will be over driven every time.
Shooting a nail into cardboard will fly right thru. Shoot a nail into steel it will not penetrate. Shoot a nail into plywood will go deeper than shooting a nail into plywood and a rafter.
If you adjust the pressure to get the shiners at the correct depth, the gun will never properly seat a nail into the plywood with a rafter.
I hope someone does the experiment soon. I will be happy to be wrong.
I understand what your saying. I see both scenarios frequently.
We can all agree that this is an over-driven nail.
The first time (several years ago) I brought this topic up (in an attic) at a “meeting” with a big builder it was to point out that the wrong nails (too short) were used for sheathing fastenings. The fast talker immediately claimed the nails were not too short, they were under-driven. I looked at him and said “well that’s a problem then”, he shut-up. That prompted me to get the 4 digit accurate caliper, I then began measuring nails at every inspection possible. Many times the nails are properly driven, many times they are not.
Bottom line, there are systemic roof installation defects ongoing in my area. I have seen some improvements recently from some builders.
BTW I’m no fan of Al, it’s clueless or even (purposely?) not factual on many issues/subjects.
Agreed. I find some uses for it but I have to correct or modify almost all the information received. It helps me brainstorm ideas, organize complex topics. Anyone who is copying and pasting this information will be in a world of hurt. I consider myself as the “peer review” and nothing gets by my gate without scrutiny and additional reputable sources.
I am kind of surprised by all the copying and pasting directly from AI on this forum by some. It is like they think they are copying and pasting an unquestionable truth. SMH
Interesting stuff from Dr. David Prevatt University of Florida storm damage researcher.
Wind Uplift Capacity of Foam-Retrofitted Roof Sheathing Subjected to Water Leaks
Failure of roof sheathing during extreme wind events is a common failure mode in residential roofs. The majority of hurricane-related losses are sustained by residential homes and 95% of these are from failures within roof-systems (Baskaran, Dutt, 1997). Inadequate fastening of wood sheathing to roof framing members is the most common failure mode. Roof sheathing failure causes major losses for two primary reasons: (1) the loss of diaphragm action weakens the lateral stability of the roof, leading to roof failure and progressive collapse of the building; and (2) openings made in the roof can allow water to intrude which severely damages interior components and building contents. Despite enhanced building code provisions that have improved the construction of newer homes, over 80% of the existing residential housing stock in these hurricane-prone regions were built before any building code changes (Datin, Prevatt et al., 2011). Thus, a significant portion of the existing housing stock remains vulnerable to these damages. Therefore it is beneficial to identify viable retrofit options to improve the uplift capacity of these vulnerable roof systems.
