Installing house installation (batts) (1 Viewer)

[Jay H]

Now that I figured I'm going to use R25 to insulated the second floor crawlspace floor and R19 to insulate the crawspace walls, I have a question about actual insulation.

It appears that long time ago, the cotton insulation batts installed on the floor was installed paper side down, with the insulation open to the crawlspace. The walls seem to be installed paper side out to the crawlspace.

My limited understanding, I would think that for the unheated crawlspace, the insulation batts on the floor should have the paper side up, towards the crawlspace, which would sandwich the insulation material itself between the crawlspace floor and the paper (giving the airspace in between the insulation power). However, for some reason, the insulation I see on the floor has the paper side down and stapled to the ceiling rafters....

Shouldn't the paper side be facing up and into the unheated crawlspace??? Same with the walls on the second floor?

Jay

 

[mylan]

Well, the paper side is a moisture barrier, so everywhere you want to keep moisture out the paper should be faced that way. For an unheated basement, the paper would go towards the floor so you would see insulation, the walls would be paper side in. All first floor and second exterior walls would have paper side in, insulation out.

 

[Jay H]

Hmm, this isn't a basement but I guess it would be an "attic crawlspace". I have a expanded ranch with 2 bedrooms on a converted loft. Next to the bedrooms on the second floor is a crawlspace that is sloped because of the roof.

On the floor the insulation is faced down, so I can see the cotton insulation, however, the insulation on the walls is faced out, I can see the paper.

I read online that:


OK, that seems to suggest that the floor is right, the paper side is down, towards the moisture producing first floor.

But then why should the walls have the paper side towards the crawlspace? wouldn't the moisture be from the second floor bedroom?

How about ventillation, the attic crawlspace is probably vented to reduce condensation, wouldn't that introduce moisture to the crawlspace anyway?


[edit] maybe the confusion here is that the attic crawlspace has three sides, the floor, the roof itself and the interior wall.

I think it is agreed that the floor should be insulatied with the vapor barrier facing down, towards my first floor living space.

The interior second floor wall is insulated with the vapor barrier facing the crawlspace and not the bedroom. The roof rafter is not insulated at all. Is it right in that the paper side should be facing the crawlspace or the 2nd floor bedroom. I think what I posted seems to indicate that the paper should face the bedroom and not the crawlspace??
Jay

 

[mylan]

I'm trying to wrap my mind around what you are calling a crawlspace and working with knowledge gained through building a house two years ago but I would not worry about insulating interior walls, its not even done anymore, I was shocked but we toured many homes under construction, even high dollar customs and not one had any interior insulation. I think this is due to the fact that a vapor barrier exterior wrap is used and the houses are pretty tight anyway so the entire interior acts as one space.
A.F.A. attic ventilation, ridge vents are the way to go, instead of the turbines that you used to see everywhere. No, rain will not enter either, the vents actually permit airflow that prevent moisture and heat build-up.

 

[Jay H]

This is an OLD house, and I definitely want to insulate the walls. There was a section in the closet that had no insulation on the wall (fell off??? I don't know) and I know this past winter, the wall was very cold to the touch so I know I am losing heat there.

I always thought the paper was a way to trap air in the insulation material itself so it would act like a double paned window. Didn't know it was a real vapor barrier...

Going to look at websites to see if I can figure out the wall. Worst case scenario, I can ask the Lowes folks when I go..

Jay

 

[mylan]

Yes, for an older house with no house wrap, I would insulate interior walls as well, but if the crawlspace/attic is on the other side of that closet, I would treat it as an exterior space and put the paper towards the heated space.

 

[todbnla]

Just a thought, I am remodeling an older house too (thanks Katrina, You MF'er! ) and I went with spray in FOAM insulation, much more energy efficient, but of course more costly too. Just a thought...

http://www.advancedinsulationla.com/

 

[Jeff Ulmer]

As has been mentioned, the paper goes on the warm side. Does the "crawlspace" attic have insulation on the ceiling? If not the the paper goes to the inside wall. The basic concept is outside>insulation>vapor barrier>inside. The paper does not add any insulating value, and these days isn't used much at all as it doesn't conform to code. You would need a seamless poly sheet on the inside of the building (weight depends on regional codes) to be an approved vapor barrier.

 

[Jay H]

OK, nope, the "ceiling" is basically the roof! which is uninsulated, so it sounds like the paper should be on the inside for the floor and the wall. OK! The house doesn't have any kind of poly sheets aka house wrap or anything of the sort.

I did read that the only time the paper should be on the outside of an attic is for hot and humid climates, like say parts of florida, but NJ is not florida so I'll stick the paper in.

Foam, foam would be nice but I am poor so whatever major constructions projects I can do myself, I will! Lowes right now is offering 10% if I sign up for a Lowes card so tonight is my trip to Lowes to buy insulation and some other odds and ends.

Jay

 

[Jeff Ulmer]

Just an FYI, house wrap (Tyvek) and vapor barrier are two seperate systems. Tyvek is installed on the outside of the house, basically as a wind barrier. Vapor barrier is installed on the heated side of the insulation, under the drywall.

Have fun with your insulation install, for me, that job ranks right up there with fixing sewage lines, which is why I still have a pile of unopened batts lying around here.

 

[Jay H]

Thanks Jeff, I knew the Kraft paper isn't a true vapor barrier, just taking liberties with my terminology.

Went and bought 4 9-packs of R19 for the walls. I'm thinking since the floor insulation is not in bad shape (gravity!), is it OK to simply add insulation, perhaps R13 unfaced to the existing insulation. I would be mixing cotton and fiberglass though....

Jay

 

[Jeff Ulmer]

Yes, adding more insulation is fine. Around here R40 for the roof is code, R22 in the walls is normal too.

 

[Jason L.]

I had my ceiling insulated and the paper side was stapled to the bottom of the floor joists. How else would you fasten the insulation in place any other way?

 

[Jay H]

If you're asking how do people install batts with the paper on the outside of the wall being insulated. I believe it is done because the paper extends an inch or two outside the insulating material (fiberglass, wool, etc) and then if you're insulated between beems, you can staple the paper to the beams without compressing the insulating material too much.

jay

 

[LewB]

I always thought that the insulation was just a tad wider than the bay it was supposed to go in. Like if the studs are 16" on center, that makes the gaps 14.5" ( 16 - (half the width of the 2x4 which is really 1.5" x 2)). So that would make the insulation slightly wider than 14.5", allowing friction to hold the insulation in place. As for other means of fastening the insulation, the insulation in my crawl space has pieces of stiff wire bridging the bay to hold up the insulation.

 

[Jeff Ulmer]

The batts will friction fit if they don't have paper on them. This also provides a better seal in some cases if the joists are a little further apart than the batt is wide. The main thing is that the vapor barrier is on the heated side of the wall/ceiling.

 

[mylan]

Also there is something called tiger bars. They are long thin metal rods that bend into place. You can get them at Home Depot.

 

[Jay H]

Aha, finally got around to removing the old decrepid insulation and installing new R19 on the crawlspace walls on friday.

The space between the wood beams is about 18" and the batts are 23" wide so I simply stuffed them into the gaps, backing paper flat against the wall. They stay fine now without any stapling or anything other than friction but will they compress and slowly fall out over time? I'm wondering whether I should try to staple the paper to the sheetrock or not... advice? I could wait and see I guess but any experience?

Jay

 

[BrianW]

Jay, excessive moisture will eventually cause the insulation to compress and collapse, but if excessive moisture isn't a problem, then it should be fine to leave it as it is.

You should be aware that compressing it diminishes its insulation capability, but it's probably not enough to worry about. It sounds like you did just fine.

Let us know how much difference it makes.

 

[Jay H]

Well, I went staple happy yesterday and unfolded the extra kraft paper from the ends and stapled that to the wall rafters. I had to go buy more 8mm staples too.

I am using R19 for the walls and I got half of the crawlspace walls done last night. It's cool that both Lowes and HD are running rebates on insulation now cause I need to buy some R25. I am going to lay R25 either unfaced or JM "comferttherm" which is wrapped insulation on the floors over the existing insulation that is there. I gather I wont need to staple them. But I haven't bought the R25 yet so I'm going to make use of the gift cards from either Lowes or HD, depending on which one is better. I do have a 10% coupon for HD and I am going to look at updating my bathroom with a new vanity and shower door...

I have another question:

It looks like there is a gap between the ceiling of my second floor bedrooms in my expanded ranch house, and the actual roof. Small, perhaps 10-12" most. The same decrepid cotton insulation appears to have been layed up and over the gap here but there is no way I can possible get in there unless I remove the roof. I know of three options:

1)Don't bother with it. Nobody lives upstairs in any case and it's just storage for all my hiking/biking/kayaking/mountaineering gear and a bunch of boxes and stuff from my HT and odds and ends.

2) Use those insulating boards that they sell. Don't seem to have a high R value.. something like R3...

3) Blown in insulation, assuming one can fit the tube in that space, I can kind of shoot insulation up there.

Right now, I'm leaning on #1 but just thought I'd put this out there for any other opinions. I'm not rich either so I'm not sure if it is worth it right now to go the extra mile to get blown insulation etc...

Jay