Brian,
I agree with most of what you are saying, but unfortunately, I do not write books, I just have been dealing with the actual problem facts for the past 40 years that’s all ha. ha.
I thought putting this together might help all of us, but not all, as I surmise.
Understanding Nail Pops in Drywall
For those that think this is all above and beyond the SOP, they are correct.
I put this together to get a better understanding on the subject in conjunction with all other opinions.
This is where we all learn and I love it.
With the knowledge learned on this Board, one can go out on an inspection and feel the vibrations of the education knowledge shared by so many. Understanding why, sometimes helps one’s understanding of what the problem may be. The final report may read “needs repair or replacement”, but at least I know what caused it or contributed to the problem.
To understand this concept of nail pops, one would have to ask himself, is the problem with the head of the nail/screw popping out or is it recessed and looks like an inverted pop? That is the question.
The Residential Housing Market built, utilizes more than not a drywall interior sheathing of ½” in thickness and in most times the IRC will allow them to install this product thickness of ½” on ceilings framed on ceiling joist with no strapping or furring and directly applied to framing of 24” o. c. spacing. R702.2.1 and R702.3.5.
Compound this with insulation weight and high moisture content of the wood; well there you have it.
In most of these cases you will see the inverted dimple more so than a nail pop.
Same scenario would apply for walls where the builder used kraft faced insulation and faced stapled to the studs and the drywall contractor is not conscious of the pressure applied to the drywall when installed. The wood starts to shrink and will pull the screw head in along with it or stay behind, and thus a drywall pop.
In cases where you see nail pops near the exterior walls, would normally be caused by the flexing of the roof trusses from wind uplift that is really negligible, but enough to cause it’s flexing to show up as a pop nail/screw.
This would be where one would have to adhere to no screwing or nailing within 16” from walls. Ceiling goes up first and the wallboard on the exterior prevents sagging. Shrinkage of the top plates could be another contributor of this.
Now we get into the science of the framing lumber and moisture contributing factors.
**Wood and water **
In the living tree, wood is saturated with water. Some of it fills the cavities of wood’s hollow, straw-like cells; some of it swells the cells’ walls. To increase its stiffness, strength, dimensional stability, and usefulness as a construction material, the water must be removed. During air- and kiln-drying of green lumber, water evaporates first from cell cavities. But even when all the water in all the cavities is gone, the lumber still hasn’t shrunk. Only once water starts to leave the swollen cell walls will wood’s dimensions diminish. For almost all kinds of wood, the moisture content (MC) marking the onset of shrinkage and the lumber’s greatest dimensions -the fiber saturation point- is about 30%. As moisture content falls below 30%, wood shrinks by about 1/30 of its total potential shrinkage for each one-percentage point change in moisture content. The converse is true when dry wood picks up water and swells. Minimum dimensions are reached when wood is oven dry, or at 0% MC. Typically, the in-service moisture content of wood in heated buildings can range from about 4% to 16% annually.
Because wood’s straw-like cells are laid down in concentric circles (the growth rings), with their length parallel to the trunk of the tree, green lumber shrinks by different percentages in length, width, and thickness during drying. With the exception of some kinds of abnormal wood, shortening along the grain, or longitudinal shrinkage, is so small (about 0.1% from green to oven dry, expressed as a percentage of the green dimension) that it usually can be ignored. But shrinkage across the grain, whether around the growth rings (tangential shrinkage) or across them (radial shrinkage), is substantial, and has to be accounted for in the design of just about anything made from wood. Though shrinkage values vary widely among woods, tangential shrinkage averages about 8%; radial shrinkage, about 4%.
Unequal shrinkage and swelling in the longitudinal, tangential, and radial directions gives rise to the bowing, crooking, twisting, cupping, and other forms of warpage commonly seen in lumber. It’s also responsible for the wide checks and splits that open in large timbers used in post-and-beam construction. By cutting a saw kerf along the grain on a green timber’s hidden face, you can encourage the widest check to open out-of-sight.
**Diagnosing diagonal cracks **
Diagonal cracks occasionally appear in drywall at the corners over windows and interior doors. In some cases, over fastening is to blame; in others, the floor framing is at fault. If drywall is fastened to both header and studs around an opening, the header will pull down on the drywall as it shrinks. Fasteners in the studs resist the downward pull, placing the panel in tension, and presto! -the familiar diagonal crack. The remedy: around openings, fasten drywall to studs only.
**Stopping the popping **
The familiar fastener pop is probably the most common drywall problem that crops up when studs and joists shrink. When first fastened, drywall is driven tightly against framing. But as the wood between the fastener tip, whose position is fixed, and the edge of the framing shrinks, it pulls away from the back of the panel, leaving a small gap between framing and panel. Pressure later applied to the panel face closes the gap, forcing the fastener head to lift the taping compound. Pops are fewer and less pronounced with screws versus nails. First, for the same holding power, screws are shorter than nails, so there is less wood between the screw tip and framing face to shrink. And secondly, it takes higher pressure to force drywall along a threaded shank than it does to slide it along a smooth one.
Pops frequently appear in ceilings near the perimeter because shrinking top plates force ceiling drywall down onto the upper edge of wall panels. Prevent these pops by not using fasteners in ceiling drywall within 16 inches of walls. Pops that appear when outlet and switch plate covers are screwed down, or when interior trim is applied, may be the result of over fastening or misplaced fasteners. You can reduce the potential for pops considerably by screwing and gluing drywall. The Gypsum Association, for example, extends its screw-only on-center spacing for walls from 16 in. to 24 in. when panels are screwed and glued.
**Understanding withdrawal **
Nail pops occur inside buildings because of the initial shrinkage of the drywall. That would come first in my book, assuming that the lumber framing was of a S-Dry quality and protected from the elements before it was installed.
In a previous post, I tried to explain the fact that in most cases on this rush built homes, the drywall is delivered for installation and most times the doors and windows are not even installed.
Humidity in the drywall product is high along with the RH in the lumber framing. The drywall contractor comes in and installs the high RH drywall and leaves.
Right behind him comes the painter and provides more moisture into the board by spraying a latex paint, three coats in two days and leaves.
Well looks good at the moment until the controlled heat and humidity levels subside, and will you know it, the drywall and the stud framing are all equalizing and here comes the pop nails/screws.
So one cannot blame the pop screw to only one scenario, there are many variables involved in this cause.
To try and pin point the exact cause is practically impossible and the best thing to do is make the necessary repairs and it will eventually equalize itself to a normal condition.
So a synopsis of events here to monitor for better control of pop nails would be;
Insure that all the lumber framing is of a minimum of S-Dry #2 or better lumber
Provide shelter of the components of the dwelling framing as soon as possible to minimize the unnecessary moisture
Protect all building materials such as drywall, dry until installation and provide a controlled moisture or RH balance when installation commences.
Provide the necessary care and diligence in the installation to prevent voids behind the drywall.
Use furring at 16” centers on ceiling framing of 24” o. c. and use 5/8” drywall when possible that would eliminate a lot of problems.
Did not mean for this to get this lengthy, but trying to promote the topic.
Thank you.
Marcel 
