Kraft faced insulation installation

[thammel]

I think this should have a simple answer. When installing kraft paper faced fiberglas insulation, the question is exactly where to staple the tabs or flanges of the paper. Do they get stapled to the top or sides of the studs? It looks neater if they're stapled overlapping on the tops of the studs, but then this may cause wallboard installation unevenness.

Experience? Code? Comments?

Thanks,
Tom

 

[snapmom]

top, the less you compress the insulation the better, the very litte unevenness will not be noticed, stud unevenness would be the problem there.

 

[beelsr]

I prefer the sides and think that looks neater.

The minimal compression of the edges doesn't really matter, you'll get better "edge-gap-fill" and any good batted insulation will expand to fill the cavity anyways. Some localities' building codes require to do the face stapling. Doing the edges makes rocking much easier.

The big things to remember are to completely fill the wall cavity: no gaps, doubled-up or empty voids. If the cavity is not standard-spaced, cut a strip +1" than the cavity for a snug fit.

When it comes to wiring and pipes, make sure there's insulation completely around the obstruction: you can't just slit it and push it inthe the cavity. The "proper" way is to pull the insulation apart (delamination-style) and stuff the unfaced side behind the whatever and then lay the faced side over.

Staples! Every 8" is the standard. The "staple to the face" argument is that with overlapping the kraft, you get a better moisture barrier. If moisture penetration is that important, you a> should be using an exterior sheathing (typar, tyvek, old-school tar paper, etc...) and b> you should tape the edges as well. Regardless, cuts in the facing should be taped up.

 

[dodgeram2500]

insulation installation....say that 10 times fast...

 

[5wndwcpe]

I vote for the sides of the studs. If you're planning to use an adhesive on the drywall as I did, it will do little good glueing the sheetrock to the kraft paper.

 

[Kapn]

What about crawlspace and other overhead installations? Flimsy wire rods, or some other method?

 

[thammel]

The most compelling argument so far is gluing the wallboard to the studs - therefore I think the insulation should be stapled to the sides of the studs.

Second issue - what about overhead and crawspaces, etc.? Overhead if going to be finished with wallboard I'd do the same way as walls. If a crawl space ( I do have that situation), I guess the kraft paper should face inward to the living space, so kraft is probably not required, but if that's all you have, then I'd be inclined to have it face in. Another answer may be to put it facing down (out) for support but then cut random slits all over the place to prevent humidity buildup. The wire rods provide another solution.

Tom

 

[beelsr]

damn, i can't believe i left that out. stupid fingers....

i even inferred that in the show redo thread...

I vote for the sides of the studs. If you're planning to use an adhesive on the drywall as I did, it will do little good glueing the sheetrock to the kraft paper.

 

[beelsr]

Overhead gets either filled in from above once the sheetrock is up using cellulose. Or you put it in and staple as you go, instead of stuffing it all in and stapling the whole thing at once. You can stuff a few feet in at a time and it will stick in place since the insulation rolls are slightly bigger than the cavity.

The kraft faces livable space, it's the vapor barrier. If all you have is kraft-faced and you don't want it, peel it off. Simple....

As for crawlspaces, there are many techniques to use, depending if yours is ventilated, where you live, moisture issues, access needs, etc...

Second issue - what about overhead and crawspaces, etc.? Overhead if going to be finished with wallboard I'd do the same way as walls. If a crawl space ( I do have that situation), I guess the kraft paper should face inward to the living space, so kraft is probably not required, but if that's all you have, then I'd be inclined to have it face in. Another answer may be to put it facing down (out) for support but then cut random slits all over the place to prevent humidity buildup. The wire rods provide another solution.
Tom

 

[Kevin54]

The paper is made to staple to the face of the stud. By doing so creates a moisture barrier all of the way across plus is additional in helping stop any air infiltration. If you are planning on glueing your drywall to the studs, then you either used unfaces or tuck the paper to the inside. By pushing the insulation into the cavity far enough to staple to the side of the stud, you are compressing the insulation. As for overhead as in a crawlspace, they make wites that are sharpened on each end that goes between the joist. In a crawlspace you do not want to use any paper faced insulation as it can and will draw moisture. With drywalling a ceiling with attic space above it, I have always found it easier to insulate after the drywall is up. The last that I did was my 28' x 38' garage with R32 batts. The wife and I had it done in approximately 2 hours. The hardest part was getting the bundles through the attic opening

 

[ScaldedDog]

On a related note, what sort of vapor barrier is used for a sheetrocked ceiling, particularly when installing bats or blowing in cellulose after the rock is up?

Mark

 

[kbs2244]

If you vist a house under construction you see the insulation stapled to the side of the studs so they drywall guys have a smooth surface to work with.
They used to depend on the thickness of the studs for vapor resistance.
If they put up poly for a vapor barrier, they pull it tight.
But I have seen the dry wall guys cut through it to get their glue onto the wood.

You will also see ther is no vapor barrier in the celing. You want the moisture to go into the attic.

Get a construction book with a good chapter on insulation. There is a lot of mis-information out there and some of the things you should do seem not quite right.
A good book will explain the why behind the way.

 

[redsky49]

With all due respect to beelsr, I have to take exception to his statement:

"You will also see ther is no vapor barrier in the celing. You want the moisture to go into the attic."

While contractors frequently will omit a vapor barrier in ceilings, this is certainly not the ideal approach. Just as in walls, a vapor retarder is needed in ceilings exposed to outdoor temperatures. The greater the difference between indoor and outdoor conditions, the more important the vapor retarder becomes.

For any insulating system, at some point in the depth of the insulation you will reach the dew point temperature. For an (over simplified) example, let's assume 70 degrees in your garage and 30 degrees outside. At the mid point of the insulation it's roughly 50 degrees. As you move closer to the outside, the temperature drops further. Once you reach about 48 degrees you have hit the dew point and moisture from inside the garage will condense in the insulation. The more interior moisture entering the wall or ceiling, the more that moisture will condense on the insulation. Wet insulation does not insulate well and typically leads to other long term problems - mold, mildew, rot, fungus, etc..

it is quite easy to calculate the precise point of condensation for any indoor/outdoor conditions as well as any wall or ceiling construction. Indoor swimming pools, for example, are a real challenge in northern areas. I would always recommend a carefully installed vapor barrier/retarder for any surfaces
exposed to outdoor conditions.


Here is linky for a typical garage ceiling insulation:

http://www.hammerzone.com/archives/energy/insulation/ceiling_1/garage_r11.htm

 

[mpraddict]

I would always recommend a carefully installed vapor barrier/retarder for any surfaces
exposed to outdoor conditions.


Here is linky for a typical garage ceiling insulation:

http://www.hammerzone.com/archives/energy/insulation/ceiling_1/garage_r11.htm

Not in southern climates. There are areas with more cooling degree days than heating degree days where use of a vapor retarder is not a good idea (Florida comes to mind). IF you use a retarder in these areas, it needs to be placed on the outside face of the studs rather than inside, but still not a good idea in these regions.

 

[kbs2244]

redsky:
I won't get into this argument again.
We have been through it more than once.
You do not want a vapor barrier between a heated area and a cold, well ventilated attic.
Your post shows a guy doing it wrong.
Get a good book

 

[brad d]

I dont see how that stuff can make a good barrier up here we use 6mm ploy with a sealant on the sill and head plates then tuck tape around al the plug boxes and other openings on the walls and roof.

 

[redsky49]

Easy there kbs. Response was directed to original poster who lists Maryland as home. Wasn't intended to step on your toes. Just a helpful opinion based on professional experience, which I still stand by.

As to the use in Florida, I agree that this is a different case.

Which book(s) do you recommend by the way?

 

[Steve in Mi]

redsky:
I won't get into this argument again. Good because I'm tired of hearing you give this misinformation.
We have been through it more than once. And each time you are misinformed.
You do not want a vapor barrier between a heated area and a cold, well ventilated attic.
Your post shows a guy doing it wrong.
Get a good book

It has been explained to you but you have a mind set that doesn't align with reason, too bad. Oh and your past argument that the contractors are doing it your way and some books explain it your way - well they are wrong too. Just like in 'follow the money' here you have to look at 'where the dew point is'. Until you grasp that concept you will no doubt continue to mislead people.

 

[beelsr]

With all due respect to redsky, I didn't say that (post #12).

With all due respect to beelsr, I have to take exception to his statement:

"You will also see ther is no vapor barrier in the celing. You want the moisture to go into the attic."

 

[redsky49]

Sorry beelsr, I mis-attributed that to you.
Seems like I opened a can of worms here.

 

[david taylor]

kbs2244 tells redsky to read a book, when it should really be kbs2244 who needs to do the reading. Redsky is more in tune with the proper way to insulate and attic. I've been in construction for over 20 years and my specialty is the thermal properties of buildings. In any design, one wants to minimize the transfer of moisture from the living space to an attic. If you are using kraft face insulation, most codes require 1 sf of ventilation for every 300sf of attic floor - twice as much ventilation is needed if you do not use it. You also need to make sure that ventilation is equally distributed, and if you are relying on vents or louvers, to make sure you calculate the net open area of each opening. If you want to use twice as many vents, that choice is there, but it's not a choice that higher-end builders would make because they will also consider the design aethetics of the building envelope.

 

[jerry j]

Steve, Redsky49, and Dave.......

You guys are SPOT ON...

CONTRACTOR FOR 30+ YEARS.. Enough said......