Nail pops at the base of vaulted ceiling-no roof leak

[mdavis5]

I have been building houses for the last 8 years and now new to home inspections. I have seen this happen in homes that are new. I would have to agree with the other guys on the expansion and contraction of the materials and not moisture, if it were a bathroom however I might consider that as a possibility.

[Brian A. MacNeish]

Originally Posted by mdavis5

I have been building houses for the last 8 years and now new to home inspections. I have seen this happen in homes that are new. I would have to agree with the other guys on the expansion and contraction of the materials and not moisture, if it were a bathroom however I might consider that as a possibility.

Drywall nailpops in new construction are almost always caused by wood shrinkage although the installer can be a bit slack and this leads to popping also.

From a building website:
"Nail pops can occur for a variety of reasons. One common cause of nail pops is 'operator error'. The installer fails to push the drywall firmly against the framing lumber as it is being fastened. This failure results in a void space between the back of the drywall and the framing lumber. If someone or something pushes against the drywall, the drywall goes in and the nail pushes to the surface.

However, lumber shrinkage can create the same identical effect, even if the drywall was properly installed. Because shrinkage causes the greatest dimensional change along the lumber's width, a void area can develop between the drywall and framing members."

Expansion and contraction of materials are caused by (1) uptake and release of moisture and (2) heating and subsequent cooling of the material.

You have ruled out the moisture related shrinkage caused when materials dry out so the expansion/contraction caused by heating/cooling must be the culprit. This should be a yearly phenomenon due to the extreme temperatures of winter/ summer at this location.

The nailpop caused by drying shrinkage is a one time effect and does not return after the screw/nail is fully driven and the surface re-finished. The yearly expansion/contraction means the surface cannot be finally finished as it will just comeback again in 6 months again when the other temperature extreme is attained. This is what happens with the phenomenon of "truss uplift"......you can hide it at construction or later on but it will always occur (as long as we need high levels of insulation for energy conservation).

SO......if the nailpops were repaired once and never come back.....drying shrinkage would be the problem. If they came back yearly, expansion/contraction by heating/cooling would be the problem.

If there was a structural deficiency and movement due to lack of collar ties, the effect at this cathredral style ceiling/supporting wall intersection would be a stress crack along the joint, not the odd nailpop.

My money's still on the drying shrinkage!!

[Marcel R. Cyr]

I posted this on the similar subject.

http://www.nachi.org/forum/f18/wallboard-screws-poping-out-2892/

Marcel

[gporter]

Originally Posted by dvalley

Nail pops are a common occurance in all new construction and are basically a simple fix.

As many have already stated here, it's simply the high moisture content in the lumber. Framing lumber used in new construction often shrinks after it is installed. Kiln dried lumber often has a moisture content that ranges between 15 - 20 percent. The moisture content can drop to 10 percent after installation.

Also, if there's a lot of rainfall during the rough framing and the lumber is stored outside and not covered up, some builders typically do not wait for the framing to completely dry before the drywall is installed. Now you've got moisture laden framing that'll take longer for the drying process, causing nail pops as it dries.

Another common cause of nail pops is "operator error". The drywall installer fails to push the drywall firmly against the framing lumber as it is being fastened. This failure results in a small void space between the back of the drywall and the framing lumber. If someone or something pushes against the drywall, the drywall pushes back into the gap and the nail pushes right out to the surface.

If framing lumber is allowed to dry properly and drywall screws are utilized, nail pops will likely not occur.

Correct David

[Brian A. MacNeish]

Originally Posted by mcyr

I posted this on the similar subject.

http://www.nachi.org/forum/f18/wallboard-screws-poping-out-2892/

Marcel

Marcel:

In the following, I quote from one book , Drywall Application, of a 13-14 book Builder's Series put out in the mid 1980's by Canada's national housing agency, Canada Moprtgage and Housing Corporation. If there is excessive moisture and air humidity in a building, the condition may lead to sagging or wavy ceilings in properly installed drywall. No where do they mention excessive interior moisture as a cause of nailpops.

Their format is as follows:

PROBLEM- Sagging or wavy ceilings

CAUSE - Excessive moisture and humidity
Texture spray too wet; high humidities (my ed.- from spray painting) and poor ventilation during construction; moisture in attic. Moisture absorption will soften the gypsum core.


PROBLEM- Nail pops

CAUSE - Wet framing lumber
Framing lumber should not exceed a moisture content of 19% (the maximum allowed by the National Building Code). However, in many parts of the country, and particularly in Eastern Canada, the moisture content of framing lumber is often much higher. As this lumber dries to 12-14% (6-9% in mid-winter and in drier climates) shrinkage occurs , the stud pulls away from the gypsum board, and any subsequent movement of the board causes the nail to "pop". A 10% change in moisture content can cause a spruce or fir stud to shrink up to 1/4"


CAUSE - Misaligned or warped studs


CAUSE - Fastener length or type
Longer fasteners actually worsen the problem of nail pops, since shrinkage takes place over a greater length of nail.


CAUSE - Fastening techniques
It can be difficult to hold the board and nail at the same time. Thicker insulation often prevents good contact between the board and framing.


CAUSE - Vibration
Exterior fastening of brick ties, siding or trim can loosen drywall nails


See:
http://www.waltersforensic.com/artic...g/vol6-no1.htm

From this article:
"The mechanism for ceiling pops can be related to shrinking of the top and bottom wall plates, which forces the drywall on the wall against the drywall on the ceiling, again causing the gap between the face of the wood framing member (in this case a ceiling joist or truss) and the backside of the drywall to close, forcing the head of the fastener through the face of the ceiling.. Truss uplift can also cause movement of the ceiling, causing popping, as well as other problems. Popping caused by either of these mechanisms usually occurs at the perimeter of the room."

The highlighted text seems to confirm my theory stated in an earlier post!!

[David A. Andersen]

There is a lot of "could be" stuff here which is well worth the education, however lets look at the fact in the last picture.

The nail is too close to the juncture of the ceiling/wall and ANY movement from ANY cause will cause the nail pop.

I report this excessive nailing and incorrect placement (a known) in my report and keep away from other speculation of the cause unless it can be proven at the time of inspection.

SOP states the "cause" of a defect is not a reporting requirement, just the "defect". Anything else leaves you open for error and potential negligence claims.

[homebild]

"The nail is too close to the juncture of the ceiling/wall and ANY movement from ANY cause will cause the nail pop.

I report this excessive nailing and incorrect placement (a known) in my report and keep away from other speculation of the cause unless it can be proven at the time of inspection. "

Too 'close' by what standard?

Building codes require placement of fasteners in the location you claim is 'too close to the juncture of the ceiling/wall."

Likewise, by what standard are you citing that supports your 'excessive' nailing claim?

Codes cite minimum distances between fasteners for drywall but say nothing about excessive or too close fasteners.

So just what 'standard' are you appealing to support your claims?

Or are you just making them up?

[Marcel R. Cyr]

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

[David A. Andersen]

I'll copy and post it from a published document when I get a chance.

Too 'close' by what standard?

My standard is good enough for me.

Building codes require placement of fasteners in the location you claim is 'too close to the juncture of the ceiling/wall."

I don't do building codes.

Likewise, by what standard are you citing that supports your 'excessive' nailing claim?

My standard which is good enough for me.

Codes cite minimum distances between fasteners for drywall but say nothing about excessive or too close fasteners.

I don't do building codes. Feels like I'm stuttering here!

I know what WORKS, I don't care what the CODE says. I'm not building a house. Why is it popping Mr. Home Inspector? Because your alleged code standard has nails installed too close to a cathedral ceiling/wall juncture.

So just what 'standard' are you appealing to support your claims?

I think I'm about to start stuttering again!

Or are you just making them up?

No more than the HI standard your making up!

[David A. Andersen]

Copied without permission from: Manual of Professional Remodeling by Jack P. Jones

"Old Carpenters Rule: Common sence is the craftsman's best tool."

[homebild]

Originally Posted by dandersen

I'll copy and post it from a published document when I get a chance.


My standard is good enough for me.

I don't do building codes.

My standard which is good enough for me.


I don't do building codes. Feels like I'm stuttering here!

I know what WORKS, I don't care what the CODE says. I'm not building a house. Why is it popping Mr. Home Inspector? Because your alleged code standard has nails installed too close to a cathedral ceiling/wall juncture.

I think I'm about to start stuttering again!


No more than the HI standard your making up!

-------------------------------------

Just as I thought.

You have no clue what you're talking about.

The 'standard' is the gypsum board manufacturer's installation instructions and what the Gypsum Association's publication ga-216
states:

"4.9.1 The floating angle method of application shall be PERMITTED to be used to minimize the effects of truss uplift and nail popping in areas adjacent to wall and ceiling intersections...."

"4.9.2.1 First fastener...shall be located not more than 7" from the intersection (sic...floating angle) or 12" when double nailed."

Since you don't know, the Gypsum Association's installation standard is THE standard for all gypsum board installation across the country and is what the International Residential Code refers to for it's guide to proper gypsum board installation.

The Gypsum Board nor the IRC simply 'make up' their own fantasy standards as you have done, but rather base their findings on scientific research and 3rd party certification testing.

What you claim is pure nonsense and by making such nonsensical claims embarass yourself and your profession.

For the industry standard for gypsum board installation, see this link:

http://www.gypsum.org/pdf/GA216-04.pdf

USG's installation instructions for their Sheetrock brand of gypsum board states:

"Space nails maximum 7" apart on ceilings, 8" on walls (and) at least 3/8" from ends and edges."

Far cry from the 'made up' silliness regarding fastener spacing for gypsum board you have claimed.

Time to get with the program or find another line of work....

[rwand1]

Hey Homebild, I just looked at your profile, and you don't have one. You claim to be a BCO, but why know name? Are you hiding your curricular activities here from your employers? Is that it?

It would behoove you to back up your great posts with a proper name if you please.

[bknowlton]

Although not usually found in a cathedral cieling, the moisture problems are exagerated when using the new blown-in-wet insulation. Many contractors don't wait for the insulation to dry before rocking.

[David A. Andersen]

Far cry from the 'made up' silliness regarding fastener spacing for gypsum board you have claimed.

OK smart *****. Can you read?

I posted:

The closest nails should be 7 to 8 inches away and double nailed.

You posted:

"4.9.1 The floating angle method of application shall be PERMITTED to be used to minimize the effects of truss uplift and nail popping in areas adjacent to wall and ceiling intersections...."

"4.9.2.1 First fastener...shall be located not more than 7" from the intersection (sic...floating angle) or 12" when double nailed."

What you claim is pure nonsense and by making such nonsensical claims embarass yourself and your profession.Time to get with the program or find another line of work....

I will venture to guess that you are not a Home Inspector, as you would realize that we report the facts as we see them at the time of inspection. We can not assume some improper method of applying wet insulation, or any other alleged cause. Also you would know that "determining the cause" is not within our scope.

One thing I could say about this inspection is that the nails are right up against the joint and movement from any cause may pop the nail. This is what the floating angel is about.

The large mud joint is going to cause elevated moisture to react with the framing, is it not? Nail placement in that joint is just asking for a pop.

"Space nails maximum 7" apart on ceilings, 8" on walls (and) at least 3/8" from ends and edges."

If you post the whole thing, we may find that they are not discussing the ceiling/wall joint, rather the board to board joint.

[Doug Edwards]

Just imagine some of the information that never gets shared in this BB because when someone does try to help some other individual(s) thinks its their perogative to try and hand them their heads on a pike. So the person who may really know the correct answer never bothers to reply and merely sits and watches the floor show.