Thread: is exposed paper vapor retarder allowed here?

Large fully-floored attic extending over attached two car garage, unconditioned space (the vapor retarder is reversed) accessed from bedroom via full sized interior door (visible on left in picture).

Obviously the space is intended to be used as storage, but is also large and high enough so that someone might use it for something like exercise or home office space.

As I understand it, the exposed paper is acceptable in this location, is this correct?

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I'm pretty sure not.... the warnings on the material usually say the facing will burn and should not be left exposed. I'm not aware of any exceptions.

The paper should be on the bedroom side.The heated space not the attic space.The instructions are usually on the paper.

Originally Posted by Matt Fellman

I'm pretty sure not.... the warnings on the material usually say the facing will burn and should not be left exposed. I'm not aware of any exceptions.

My understanding - and I'm not sure this is correct, which is why I'm here asking the question - is the exposed paper vapor retarders are allowed in unconditioned spaces (though in most cases vapor barrier will end up on the wrong side of the wall or ceiling).

Would you put insulation in a wall where both sides are unconditioned?

Originally Posted by Michael Garrity

Would you put insulation in a wall where both sides are unconditioned?

You wouldn't - the question I'm asking concerns the unconditioned side of of a wall or ceiling with heated space on the other side (as in the examples in the pictures).

My question is:, if someone installed insulation with the vapor retarder toward the unconditioned space, in addition to being incorrectly installed as regards the position of vapor retarder, is the paper face required to be covered with gypsum board?

As I understand it doesn't, as the unconditioned space is not habitable space.

What I'm not sure about is the case where unconditioned space is configured such that it might well be occupied at the some of the time - for example in this case as a home office or exercise area.
.

The insulation facings, paper or foil, are required to be in substantial contact with gypsum board or other approved material, the facings are not allowed to be left exposed.

This is regardless of where they are left exposed (no place is acceptable) and regardless of which side the vapor retarder is supposed to be on (which is always the 'warm-in-winter-side' of the insulation).

That's what I needed to know. thanks!

Don't know where I got it into my head that there were exceptions to the requirement related to unconditioned space - it didn't quite make sense to me, which is why I asked.

The reason is that flame spread across those facings is pretty good, so by being in substantial contact with gypsum board it restricts the flame spread and basically serves to snuff the fire out because it will burn up its fuel (the facing) without being able to travel far enough to keep getting new fuel.

I see this problem A LOT and it always amazes me that someone can get through an entire insulation job without reading the instructions that literally hit them in the nose.... they are even printed in spanish now.

Jerry,

The requirement makers sense to me; it was my seeming to remember that there there was some sort of exception for exposed paper facing in some unconfined spaces that didn't quite make sense to me.

But then, this is the third night in a row I've been up past midnight writing reports (I get up at 5:30 weekday mornings to drive my wife to the train), so at this point I'm surprised anything makes sense to me.

My advice to this homeowner is to use unfaced insulation only - always. This seems to be at least R19. I would think R21. The intent is good, but there is a better way, as described here at my web site.

In my experience as a contractor (Maryland) you can use the faced insulation with the face (paper) facing the unconditioned area if the face is scored to allow it to vent the moisture that will collect as it migrates from the conditioned area. The paper is designed to act as a vapor barrier to the insulation and not much more. Posed with the situation of having the insulation there I would correct the problem by scoring the paper and leaving it in place as the easiest and effective solution.

Originally Posted by Garry Sorrells

In my experience as a contractor (Maryland) you can use the faced insulation with the face (paper) facing the unconditioned area if the face is scored to allow it to vent the moisture that will collect as it migrates from the conditioned area. The paper is designed to act as a vapor barrier to the insulation and not much more. Posed with the situation of having the insulation there I would correct the problem by scoring the paper and leaving it in place as the easiest and effective solution.

wrong! see post# 7.

I believe you should refer back to Jerry's reply, do not advise to be cut, the fire issue is still at hand..

Hi, All &

Just take it out & add-in 'modern' poly vapour /air-barrier - as intact as poss. & then re-insulate !

Is that your Assistant, by the way ?


CHEERS !

Originally Posted by Michael Thomas

The requirement makers sense to me; it was my seeming to remember that there there was some sort of exception for exposed paper facing in some unconfined spaces that didn't quite make sense to me.

Michael,

That's why I gave the reason, sometimes 'the reason' sticks in the memory and leads to something sticking out where you see it where it otherwise may have slipped by just looking around knowing 'the requirement' - leads to those 'that just does not look right' moments which then leads the mind to recall 'why' it 'just does not look right'.

Just take it out & add-in 'modern' poly vapour /air-barrier - as intact as poss. & then re-insulate !

I'm curious, is it possible to get an effective air / vapor barrier this way or does the drywall or the habitable side need to be removed to provide a proper seal?

The exception to exposed kraft liner/tyvek flamable barrier materials might be in areas unaccessible or closed to persons, possiblity of storage & direct light (no scuttle, door or access to open) with fireblocking & draft stopping from other areas, and less than 3 feet high.

Originally Posted by H.G. Watson, Sr.

The exception to exposed kraft liner/tyvek flamable barrier materials might be in areas unaccessible or closed to persons, possiblity of storage & direct light (no scuttle, door or access to open) with fireblocking & draft stopping from other areas, and less than 3 feet high.

The reason I said this: (underlining and bold have been added)

Originally Posted by Jerry Peck

The insulation facings, paper or foil, are required to be in substantial contact with gypsum board or other approved material, the facings are not allowed to be left exposed.

Is because of this: From the 2006 IRC: (underlining and bold are mine)
- R316.1 Insulation. Insulation materials, including facings, such as vapor retarders or vapor permeable membranes installed within floor-ceiling assemblies, roof-ceiling assemblies, wall assemblies, crawl spaces and attics shall have a flame-spread index not to exceed 25 with an accompanying smoke-developed index not to exceed 450 when tested in accordance with ASTM E 84.
- - Exceptions:

- - - 1. When such materials are installed in concealed spaces, the flame-spread and smoke-developed limitations do not apply to the facings, provided that the facing is installed in substantial contact with the unexposed surface of the ceiling, floor or wall finish.
- - - 2. Cellulose loose-fill insulation, which is not spray applied, complying with the requirements of Section R316.3, shall only be required to meet the smoke developed index of not more than 450.