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Insulation question

VillageInspector

Sawhorse
Joined
Feb 9, 2010
Messages
211
Location
Dutchess County, New York, United States
I was told at an annual state training course that its required by NYS energy Code to staple the insulation flanges to the face of the stud rather than the side of the studs. Just recently I was challenged on this and I went into the energy code but came up empty. The IRC and IBC don't seem to offer any guidance either. What's everyone's opinion on this ?

Thank you
 
Manufacturers installation instructions have ALWAYS required the flange to be stapled to the face of the stud. I have pi.....ed off a lot of contractors over the years pointing this out. My specs have always said thi but know one seems to read anymore.
 
There is absolutely nothing in the Code about the location of staples. Installation instructions I have seen allow either face or inset stapling. I had a go round with this very issue and contacted NYSDOS about it and either method is acceptable. Some sheetrockers will not install over face stapled insulation because of screw pops. Also, if face stapled the drywall cannot be glued or sealed at he top and bottom plates. It was also argued that it would not be continuous vapor retarder if inset stapled but the flanges on kraft faced insulation are only paper and again the word continuous is not mentioned with regard to vapor retarders.

https://www.certainteed.com/resources/TB__76_-_Stapling_Methods_and_Faced_Insulation_Products.pdf
 
Why would the drywall have to be glued?

R702.3.1 allows adhesives if conforming to ASTM C 557.
Table R702.3.5 has applications with or without adhesive.

So if no poly is being used and the batt tabs are on the inside of the stud, adhesive can be used to reduce fasteners, reducing visual drywall appearance issues.
 
2018 IECC
Exterior thermal envelope insulation for framed walls
shall be installed in substantial contact and
continuous alignment with the air barrier.

If you staple to the side of the stud the insulation will not be in substantial contact with the air barrier (drywall)
 
An insulation installer convinced me that a non-continuous vapor barrier is not the biggest offence you will ever encounter. It is the warm moisture laden air passing through the exterior envelope that is the cause of moisture damage. Let’s compare a non-continuous vapor barrier vs. a leaky house.

The vapor barrier with holes or gaps at studs will allow water molecules into the cavity, through diffusion, at a rate of one molecule at a time. Yes, one molecule at a time. How many molecules before you have a problem?

How about a leaky house? Visualize warm moisture laden air traveling through exterior wall due to stack effect or prevailing winds. Warm moisture laden air moves from inside, through the exterior envelope to the outside. As this air cools while moving through the exterior envelope, it loses its capacity to hold moisture and deposits it on the closet solid object: a stud, bottom plate or exterior wall surface. Think relative humidity, as the air cools, the relative humidity increases. Leaky houses cause moisture problems.
 
Inset stapled insulation only has a small area that is not in contact with the wall covering. "Substantial" is a subjective term, is 90% substantial, I would guess there is more contact than that. It has been argued that convection currents will occur along the studs but if the drywall is sealed to the top and bottom plates (as we do) no air is introduced to the cavity and there is no stack effect.
 
Sifu's post, OC R30C insulation; There you have it, insulation can be stapled to the face or the side.
 
An insulation installer convinced me that a non-continuous vapor barrier is not the biggest offence you will ever encounter. It is the warm moisture laden air passing through the exterior envelope that is the cause of moisture damage. Let’s compare a non-continuous vapor barrier vs. a leaky house.

The vapor barrier with holes or gaps at studs will allow water molecules into the cavity, through diffusion, at a rate of one molecule at a time. Yes, one molecule at a time. How many molecules before you have a problem?

How about a leaky house? Visualize warm moisture laden air traveling through exterior wall due to stack effect or prevailing winds. Warm moisture laden air moves from inside, through the exterior envelope to the outside. As this air cools while moving through the exterior envelope, it loses its capacity to hold moisture and deposits it on the closet solid object: a stud, bottom plate or exterior wall surface. Think relative humidity, as the air cools, the relative humidity increases. Leaky houses cause moisture problems.

It depends on the climate the building is constructed in.

Diffusion is the rate at which moisture travels through a material or assembly. So, how fast water will move from one side of gypsum to the other. Even vapour barrier permits some water into the cavity through diffusion.

Air leakage on the other hand simply carries moisture laden air into the cavity. This happens any time that the building is at a higher pressure than the surrounding environment.

fig1-1-450x225.jpg
But the insulator isn't wrong. You don't need a continuous vapour barrier. In fact, many assemblies perform better without continuous vapour barriers. Air barriers on the other hand, must be continuous or you will see moisture problems regardless of your climate.
 
Code instructors can sometimes be off a bit. If the tabs are pushed back, exposing the sides of the studs, the insulation is compressed. Too much, and the r value is reduced and enough of that is bad...

How bad? So RESNET has an insulation grading method. Perfect, as per manufacturers instructions, everything split around plumbing and wiring and pretty much in full contact with the surface intending to keep warm called Grade 1, 2x4 wall R13 (with studs into account) would have an r value of 11.7 (including well done side stapled tabs)
Small areas of compression here and there and maybe some gaps here and there would be R 11.1 or grade 2

Any wall where insulation wasnt split around wires and plumbing get Grade 3 and that average R value is 10.3

So, that 2x4 wall, best to worst is difference of R1.4
Say thats 1000 sq ft of wall at a 55 degree temperature difference, equals 660 btu more loss per hour. Not too big of a deal. (U×A×Dt)

Whats makes bad juju in walls is convective air currents moving vertically in the cavity. Fiberglass lets air move easily, and depends on still air to perform. Long areas of compression or gasp, knee walls with an open back will create a loop, reducing the value even more and why encapsulation is so important..

So, if the edges of the tabs are all even with the face of the stud the 3/4" of compression is negligible, and certainly installed well enough.

Consider dense pack cellulose installed before sheetrock, the netting is stretched taught by stapling down the sides of studs to help stretch the fabric across the bays and to prevent pillowing out too much (preventing the rock from sitting tight to the wall) The real things CEO's should be looking for is insulation split around wires and plumbing, and that the insulation is mostly in contact with the surface it intends to warm. Other things like insulation in walls covered on sides, wind wash baffles and sealing rock to top plates.. The difference between face and side staple might be bigger with vapor transport, but if the cavity (sheathing) is airsealed, air will not move through the assembly. Im in a pretty close to vapor nutral area. 2 coats of paint is all we need here, so side staples vs face staples dont matter too much at all.
 
Single-family-house-with-insulation-and-window-heat-losses-copy.jpg
 
Fantastic image.. suspect the cavity to the left of the right window has heating pipes heading up to 2nd floor...
Continuous insulation under rain screen would have significantly changed this, although glass is like a hole in the hull...
Doesn't matter how watertight the other 95% is, if the bildge pump cant keep up, a sizable hole will make the ship sink..
Heating equipment works with the same analogy as a bilge pump..

Toss into this mean radiant temperature, and you have what I live in, A home built in the 50's and one that's only comfortable if the TT reads well above design...
Cold walls, Cold ceilings, and even colder glass makes my body the warmest thing in the room. While some may think this is snake oil,
its huge in the comfort game.
When walking past a cold glass window in the dead if winter, the cold you feel is not "cold coming to you" its heat leaving your body faster than your body can replace. Regardless what intuition tells you, heat moves to cold. End of story. Ice cubes don't get more cold if left on a table.

Could go on and on, but this deserves its own thread. As Im new here, not sure if my rant would be well received....
 
Fantastic image.. suspect the cavity to the left of the right window has heating pipes heading up to 2nd floor...
Continuous insulation under rain screen would have significantly changed this, although glass is like a hole in the hull...
Doesn't matter how watertight the other 95% is, if the bildge pump cant keep up, a sizable hole will make the ship sink..
Heating equipment works with the same analogy as a bilge pump..

Toss into this mean radiant temperature, and you have what I live in, A home built in the 50's and one that's only comfortable if the TT reads well above design...
Cold walls, Cold ceilings, and even colder glass makes my body the warmest thing in the room. While some may think this is snake oil,
its huge in the comfort game.
When walking past a cold glass window in the dead if winter, the cold you feel is not "cold coming to you" its heat leaving your body faster than your body can replace. Regardless what intuition tells you, heat moves to cold. End of story. Ice cubes don't get more cold if left on a table.

Could go on and on, but this deserves its own thread. As Im new here, not sure if my rant would be well received....

I am sure that your possible expertise would be well received and appreciated. Not all will agree and some may be argumentative just to argue but I am sure you can professionally vent here.
 
I have witnessed about a dozen blower door test when it is 20 degrees or less that the state will conduct with an infra ray camera and it is amazing the cold spots that appear on even interior walls. It is an eye opener for everyone that sees it.
 
The problem with this Building Science stuff is abbreviated is B.S. BUT the other problem is we have been beat into submission for so long that any change feels (quite literally) uncomfortable. I know first hand this discomfort. Every bone in our body believes this is wrong. With all of the training and education, it still took time for it to finally click for me (Talking years..)

The great thing about this is the science is easy to learn in bite sized chunks.
Not unlike a 500 piece jigsaw puzzle, learn and understand each piece and one day you wake up and see the big picture.
This is what I love about this end of it. In the last 10 years I have not come across one problem (building science related) I couldn't solve. No matter how complicated, you find is always due to something silly. Hundreds if not thousands of homes later, and never one customer cooling, heating or comfort complaint.
Thing is, some folks dont care about how a car works or how anything works. They dont want to learn, and are just looking for the $$$

Most of what I call dream customers, you know the ones who value your service, ask hundreds of questions and pretty much dot every I and cross every t, usually call me after being in the home for some time and say, OMG, I can not say how amazing my house is, or I had a hard time believing 4,500 sq ft only needed 2.5 tons of cooling but this summer that week when it was 95, my house was so amazingly comfortable every where...

The other problem, which is huge is actually 2 fold. One, you shouldn't apply any of this stuff UNTILL you know every angle. Like any high performance race car, alot can go wrong quickly. My best advise is #1 Build Tight yes, but ABSOLUTELY ventilate right. The other issue here is, and I hate to brake it to you, not everyone you trust to understand the BS actually does. I have literally lost faith in man kind over this realization over 10 years ago. I can easily pick out thousands of homes that are time bombs because the people hired had zero knowledge of the most fundamental aspects. Sure, they are like ballerinas on the dance floor, great talkers, get along with everyone. They spin tales well and are believable but honeslty have zero clue... Ahh.. Im falling off the deep edge, you get the idea....
 
The blower door test is becoming more common in Philadelphia. We conduct them at the post construction phase but I do think it would be beneficial to conduct it while the walls are exposed so that problems can be found and corrected ahead of time. The blower door is an incredibly useful tool for keeping the building air tight.

Ori Rosenkrantz
BlowerDoorTester.com
LocalEnergyAudits.com/blower-door-testing
 
NOTE: CALIFORNIA
2019 Residential Compliance Manual January 2019
The kraft paper used as facing on thermal batt insulation material is typically a
Class II vapor retarder. Faced batts may have flanges for fastening to assembly
framing. Fastening flanges may be face- or inset-stapled or not stapled at all,
as the flanges provide no moisture control. Face stapling of flanged thermal
batts helps ensure the insulation material is installed fully and properly within
the framed cavity. Flangeless batts are also common and require no fastening
as these materials maintain installation integrity through friction-fitting within the
cavity of framed assemblies. In all cases, the insulation must be installed
properly.
 

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The blower door test is becoming more common in Philadelphia. We conduct them at the post construction phase but I do think it would be beneficial to conduct it while the walls are exposed so that problems can be found and corrected ahead of time. The blower door is an incredibly useful tool for keeping the building air tight.

Ori Rosenkrantz
BlowerDoorTester.com
LocalEnergyAudits.com/blower-door-testing
FYI, unless you are a paying sponsor, I don't think you are supposed to post your website as free advertisement, and all 4 of your posts have your websites on them.
 
I was told at an annual state training course that its required by NYS energy Code to staple the insulation flanges to the face of the stud rather than the side of the studs. Just recently I was challenged on this and I went into the energy code but came up empty. The IRC and IBC don't seem to offer any guidance either. What's everyone's opinion on this ?

Thank you
If you have been part of the latest energy code trainings, you would have heard the speaker talking about insulation grading. While its not in our code books, it is by refrence with the HERS ERI path. Grade 1 fiberglass can be achieved by side staples. Alway has been able to. For those who say it MUST be face stapled, i challenge you to find where it actually states it in any manufacturers literature. The vapor barrier most often forget about is the two coats of paint, in addition to the cavity paperface. But the biggest barrier is an air tight wall or ceiling by a huge factor. How many folks Here know that the top plate needs to be sealed to the drywall where ever there is an attic space above ? Code is often written poorley, but durable gasket (best) or caulking (yuk) on the lower of any top plate, exterior walls and partition walls, is the best way to reach 3ach50. And required.
That is a tremendous vapor barrier...
 
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