Insulation...Paper up or down?

I went into the attic of my new house. I noticed the roll insulation installed had the paper side facing up (toward the attic). I’ve always heard the paper side of insulation should be facing toward the inside of a house, or toward the heated side if you will. What effect does this have?

My reason for asking is because I am going to install blown insulation in the near future so I can keep the house cooler at less of a cost from the utility company. One person said I need to flip the existing insulation so the paper is toward the heated side. What would happen if I did not? Does it make that big of a difference?


Is this a new house? You should inspect the attic, and the highest story ceilings for water damage. If the contractor is still available, it might be possible to compel him to reinstall it correctly.

Dew will collect on the underside of the paper if there is a marked temperature difference between above and below it. Hence the caveat to insulate “outside” of the vapor barrier. It makes a lot of difference in humid climates, less, but still some in arid climates, or homes with added humidity for inside regions.


It’s an older home and most likely was installed by the previous owner who was a do it yourselfer kind of guy. I walked through the attic and saw no signs of water damage anywhere.

The vapour barrier must always go towards the warm side of the building. Is the paper a vapour barrier, or just paper?

I’m not sure. It looks like the standard paper that comes on insulation you get in a roll.

How would that work?
In winter, the inside is warmer and in summer the outside is warmer (or upside/downside).

OK - When heating, the vapour barrier goes to the warm side. Sorry.

This site may be of some help:

so what it’s looking like is I need to spend some time in the attic and flip everything over. Great

If this is fiberglass insulation, I strongly recommend gloves and a mask. Nasty stuff to work with.

The stuff I installed recently said directly on it that the paper side went toward the living space with “install with this side towards the room” or something similarly obvious. Any such clue? Did you get a home inspection? A home inspector could tell you for sure.

Yes, it itches like hell.
How long has it been in place without causing damage?

This is a typical rookie mistake. Paper backed insulation is cut to fit betwen the studs or rafters and has little flaps on either side to secure the insulation w/ staples. Fuzzy side faces away from you paper towards you. Then you hang drywall over it all.

Dont know about your location, but here a ceiling installation calls for no vapor barrier. If the stuff is a little older and the asphalt adhesive/vapor bar has degraded you may be able to just pull away the backing and leave the glass in place.

The vapor barrier MUST be toward the living space.
It prevents migration of moisture to the outside, due to the large temperature difference, where it can freeze and accumulate in winter.
In summer the difference in temperature is much less with no freezing temperatures to consider.
Under these conditions it makes no difference where the vapor barrier is, in or out.

Basically you need the paper against the drywall. The “fluffy stuff” acts like a sponge and absorbs moisture. You don’t want a wet sponge directly touching the drywall.

Regular drywall (I know they have the green board for bathrooms) is pretty permeable. In the winter when you have the humidifier working, the water vapor goes right through the drywall. With the paper next to the drywall, it stops there and the insulation keeps it warm enough that it doesn’t condense. Turn the insulation around and the vapor seeps through the insulation and when it finally hits the paper, the paper is cold enough (as it is now unportected by the insulation) to condense the water that drips back into the house. Especially when installed in the ceiling.

Where is your house? Obviously different climates have different requirements, as shown by differing opinions above.

If the insulation in question was installed as an extra layer to keep a house warm in a cold climate, then you probably already have a vapour barrier against your drywall underneath the existing insulation. Take a look to see. If it is plastic, or paper against the drywall, then you can (and should) get rid of the paper on the top layer. When you blow more insulation in you don’t want to have separate layers where moisture can accumulate, so by getting rid of the top paper layer, you’ll have a single layer of continuous insulation.

I live in Louisiana. When I inspected it I did notice a thin layer of insulation under the newer stuff. The house is older and prior to having drywall it had tongue and groove boards throughout. The boards are still there and have had sheetrock hung over them. I’m thinking of ripping out the paper instead of flipping everything. The house is around 1800 square feet. The less time in the heat the better is what I’m thinking.

I wasn’t aware that you lived near the Gulf. You might want to check out this site before you decide what to do.

Ok. I want to make sure I’m reading this right. I live in the Monroe area of Louisiana, for those who have maps ready, which is in the North Eastern part of the state. According to the article you put up there I can either leave it as is or peel the paper off since I’m kind of on the cusp of the two areas. If I leave the paper on the insulation how will that effect the blown insulation I plan on adding?

Is this fiberglass between ceiling joists? Will it support blown insulation?