Which Way to Face Insulation?

Danny Lipford installing fiberglass insulation under floor.

On your show you said that when insulating under a floor, the paper facing should face up against the flooring. Why can’t I install it the other way? Does it make that much of a difference? -Kim

Hi Kim,
Regardless of whether fiberglass insulation is installed in a wall, attic, or crawlspace; the paper facing should always face toward the inside of the home. That’s because the paper contains a layer of asphalt adhesive which prevents water vapor from passing through it.

If the insulation is installed with the paper vapor barrier facing away from the heated part of the home, moisture from humid inside air can condense and become trapped in the insulation during cold winter months. This can lead to rot and mold.

For more about vapor barriers and insulation, check out our articles Vapor Barriers in Your Home and Attic and Basement Frequently Asked Questions.

Danny

50 COMMENTS

  1. just moved in my house…found out all the insulation faced is install the wrong way. will it hurt or i have change it

    • Hi Michael,
      Depending on the climate where you live, it may or may not cause a condensation problem. Colder climates, like you have in Pennsylvania, will have more chance of condensation problems than a warm climate. Assuming the insulation isn’t too much trouble to get to, I would turn it over so the paper facing is toward the ceiling, or peel the facing off all together. If it is a lot of trouble to change it, feel under it during the winter and see if it feels damp. If it does you definitely need to fix it to prevent rot or mold.

  2. I am remodeling a shower stall and going to re-tile, when I did the demo I noticed the insulation was faced insulation and the paper was facing the outside. The shower has two outside walls. I live in the Sacramento valley area which gets very hot and dry in the summer, doesn’t get to cold in winter, but foggy damp days in the 30’3 and 40’s. So I am not sure which way to install the new insulation. I have install new insulation becasue of a valve leak got the old stuff wet.

  3. I sent an email to owens corning asking them which way to put the paper in my case, They told me the paper goes to the warm side of the wall in winter type weather. which would mean for me the paper faces the warmer inside

  4. I had a guy come over from the electric company to tell me how to save on energy cost. Some of the insulation in the attic is the stuff that blows on and doesn’t have a paper side. He said since it was low I could roll out R-30 on it, which I did. I put the paper side facing toward the inside of the house. Is this going to cause condensation in the winter and rot the insulation under the paper/water vapor and therefore the wood? I live in Fort Worth TX.

    • Hi Matthew,
      You can lay rolls or batts of fiberglass insulation over existing blown in insulation, but you need to use unfaced insulation to prevent moisture from being trapped between the layers. Since you’ve already purchased and installed faced insulation, your best bet is to peel the paper facing off the insulation you installed.

  5. I live in Louisiana close to New Orleans, should I put my fiberglass insulation with the paper side facing the outside of the house, or paper facing inside towards the room?

  6. Which way should the paper face on insulation when insulating an attic wall between an attached garage and the house?

  7. we have a camp which is off ground with a patio like under it. we insulated the floor of camp but birds and wasp have built in it. we would like to cover it with something any suggestions, we are thinking about psk insulation would that cause moisture to build up. i want the paper side facing down, and suggestion will be appreciated

  8. I installed my insulation r30 under my cabin crawl space with paper side facing the ground, is this the wrong way? I live in north Ga. mtns near N.c line. Do u think its gonna be ok like I have it?please reply soon.

  9. I bought an old mobile home. I updated the water lines to pex. I removed the skirting and went under and the insulation was non-existent. And what was there was thin and about 1″ thick. I plan to put r30 unfaced insulation under it and wrap it with the correct plastic. Also the mobile home has aluminum siding attached to 1/4th board nailed to the studs and the insulation in the walls was the same as under. About 1″ thick. I live in pa half hr 45 min north of Pittsburgh. There is a river about 1/32 of a mile away that keeps the area damp in the spring and fall. The area is usually colder then the weather station says.
    So to my questions.
    1.) Is it economical to put unfaced r30 insulation under the home. PS: I sealed all the holes and edges under the home with great stuff spray foam as a air barrier
    2.) What way do I face the paper in the walls? It gets to -5 sometimes in the winter and 98 in the summer.
    Addendum: Also I will be keeping the house at around 72-74 degrees in the winter months for my little kids. I will also be replacing the windows with double hung windows and having blown insulation in the roof/ceiling.

  10. I am trying to insulate the underpinned of a mobile home, I do not want to remove the metal skirting because is permanent, it will be hard to remove. So is it possible to use blue foam boards attached to the metal from outside. If is alright how should I do it in order to have ventilation and at the same time vapor barriers to avoid condensation issues ?
    Do I applied vapor barrier outside the metal then the blue foam boards, plus plaster or first the blue foam the vapor barrier and then the plaster or blue foam, plaster vapor barrier.
    the problem is that the ground has not vapor barrier, the belly is fine not holes, the underpinned is perfect too but seems cold in the winter. Going under the house is not an option for me or my children, the best solution is fixing the problem from outside.
    Any suggestions
    thanks in advance for your help

  11. I have a metal storage building what would be the best insulation to use before I finish off the interior wall. right now I have nothing but 2x4on the wall to metal and the roof is 2×6 to metal

  12. just purchased a home, the vapor barrier in attic is facing up, i am going to flip it over so it faces the ceiling. I want to add more batt insulation, am i correct in assuming that i should get the “Unfaced bat” and lay it over top of what is in the attic?
    thank you,
    mike

    • Mike,
      Yes, you should put unfaced insulation (either rolls or batts) on top of existing insulation, so that you only have on vapor barrier facing the heated house.

  13. We recently purchased a house with an addition that has an unfinished, as no heat, no electricity, in the basement of the addition. What would you recommend for insulation on the ceiling of the basement /floor of the upper portion of the room. We plan on eventually finishing the room. But would like to enjoy the space during winter months
    -If pink insulation vapor barrier closest to the floor or on the out side of insulation
    -foam insulation. Is it worth the cost?
    Thank you for your time

  14. If I am using paper faced rolled insulation between rimed joist in the basement and first level subfloor which way should the paper go – towards the outide of the house or towards the inside of the house? Is it better to use faced or unfaced rolled insulation in this case?

    • Ken,
      If the basement is unheated, put the facing up toward the first story floor. If the basement is heated, insulation between it and the first floor wouldn’t provide much benefit, but I would use unfaced if you do.

    • Alex,
      Since housewrap isn’t a vapor barrier and allows water vapor to pass through it, you can put it over your basement ceiling to cover the insulation. Landscape fabric would also work.

  15. I bought Poly Shield insulation board which has an aluminum layer on one side. Should the aluminum side face in toward the heated/cooled space?

  16. Still a bit confused. I am trying to insulate above the rim joist in the basement. This is the space, roughly 12″ or so, between were the cement wall ends and the underside of the first floor is. If I use faced insulation should the paper go towards the outside of the house or the inside? The insulation is against the wall NOT towards the first floor. Or, should I use unfaced? My thoughts were I would use faced so there would be a barrier for moisture coming from the outside wall. I don’t want a potential mold problem. Can I just remove all doubt and potential moisture and go with unfaced and get a good barrier of insulation? Thanks!

  17. It is also a fire hazard to have the paper visible, as the treated paper will contribute significantly to a fire. The manufacturer’s even place a red warning on the paper. If paper is visible it musy be covered by a non-comb material such as 1/2″ gyp.

  18. Thank you Ben and Tim! Tim, I had read that paper faced insulation must be covered appropriately because of the potential fire hazzard. Thanks for giving that important reminder!!!

  19. Hello, can you put paper insulation on cold/hot water pipes? My main concern are the hot water pipes. Should i peel the paper off and safely install over it?

    Thanks.

    • Sean,
      It’s better to use foam pipe insulation than standard fiberglass insulation on water pipes. It’s easier to install and has higher insulating qualities for the thickness. Make sure you get the right size for your pipes.

  20. I have always used unfaced insulation between two heated areas. It does not make much sense only it cuts down on sound a little, I use R30 with steel wire supports, Richard

  21. This information on fiberglass and the installation of insulation is so important, thank you for sharing your advice for everyone to read. I worked for an insulation company for many years, and I was surprised at how many times people would install their fiberglass insulation in the wrong direction. I think it’s important to be educated in this kind of thing to be able to help yourself or others when the situation requires.

  22. There was not enough ventalation in our crawl which has caused the insulation to hang. Is there a fix for that rather than having to replace it all?

  23. Hi, I’m trying to replace my insulation in thw basement. some of the insulation look intact except for those in the corners. The insulation has a paper back 2 1/2″ thick. I could see the paper back as soon as I took out the wall. There is a vapor barrier after the cement wall then installed then they put 2×2 framing in different distance then the insulation and another vapor barrier. My question is was it properly installed? Can I just put additional insulation on top of the old one? I need your advise. Thank you.

  24. My husband is putting up fiberglass insulation in his barn and was wondering which way it should face if he is using it in the ceiling?

  25. I am planing to used the attic on top of the garage. I wonder what type of insulation I should use in the ceiling, and if it is necessary to insulate the floor, and what kind of insulation I should use?

  26. I have a garage door and area to store a boat in my basement (like a walk out) in the winter months. I live in MN. The floor above this space gets cold in the winter. Although there is heat in the basement, this area can reach 45 degrees in really cold months, due to the fact that there is a garage door. I was thinking of insulating this area and using insulation without paper because of pipes and electrical work in the cavities. Does this make sense? Also, can I use plastic to cover this insulation or use something else?

  27. I live in Tullahoma, TN which is about 75 miles South of Nashville, Tn. About 20 years ago, I installed fiberglass batting insulation (using wire strips)in my crawlspace floor joists with the paper facing the crawlspace dirt floor as I was instructed by the supplier. I have always had problems with carpeting wrinkling in my home and am now wondering if the batting is trapping moisture and should have been installed with the paper facing the floor of the home.

  28. I am about to replace the subfloor in my double wide and plan on replacing the insulation with R30. Should I use no faced or faced and if I use faced which way should it face. I live in Charlotte, NC.

  29. Well, insulation is certainly confusing. I’ve always seen insulation in new houses with the paper side facing inward. I just finished my basement, and the inspector told me that I have the insulation on my outside walls (those along the concrete) facing the wrong way. He told me the paper face should face towards the cement wall side. From what I’ve read, I believe he is right because of fire potential. Do I (does he) have it right. Thank You, Richard

  30. Dining room floor is very cold in the winter. It’s above the garage. Garage ceiling currently has 5 1/2 in R19 faced insulation in garage ceiling. Face side is up toward dining room, with bottom side resting on the 5/8 drywall garage ceiling. From dining room floor to garage ceiling their is 15 3/4 in. Can cellulose loose fill be blown in between dining room floor and vapor barrier of the R19 insulation.

  31. Have 90 yr old farm house attic floor insulated well! I was looking for something for the roof rafters. I see all new insulation products that will not interfere with the attic floor 20 in on center. I am in northeast Pa more cold than summer. Thank you Jim H

  32. I am a contractor and I just went and looked at a house who had fiberglass bat and insulation with the craft facing down
    it was something I haven’t seen often their floor joists had dry rotted
    Underneath the foundation was dry extra dry
    I found out that I have in the craft down away from the floor system was wrong and could cause rotting and mildew and that is what happened
    It wasn’t all of the floor joists it was just the bottom of the floor joists that was exposed allowing the aired to get to the moisture and drying it and then causing it to dry rot

  33. We have an apartment above a block garage fully above ground. Walls of garage do not have any added insulation. With two insulated garage doors. There are two heat ducts from the apartment in the ceiling of the garage which keeps the garage space on average of 50 degrees in colder months. Would insulating the floor be any benefit for energy efficiency of the apartment and if so would the batting go next to the floor.

  34. i have two problems:
    1. i have vermiculite under my living room in the garage ceiling. my living room in very cold in the winter months. can i roll out insulation over the blown in insulation.
    2. my pipes near the edge of the concrete freeze, i placed foam over the pipes near the floor, however, my pipes are frozen now. after reading all of the comments, i am still confused, does the paper go against the concrete wall?? thank you

  35. We are purchasing a used home soon, but the inspection report says that the attic insulation (paper side) is facing down, into the crawl space and should be removed & replaced since the paper side states that it is flammable. C;an it simply be sprayed with a flame retardent, or covered with dry wall or other non-flammable covering? The expense to remove and replace is high. Thanks, R.S.

  36. I am putting 1 inch aluminum sided insulation boards inside a metal building. Does the aluminum side face to the inside or glued to the metal siding? Also the same question regarding the ceiling of an enclosed wooden beam porch?

    • Hi, Carol,
      The aluminum facing should always face toward the inside of the home (whether in a wall or ceiling) to prevent water vapor from passing through it.
      There’s just one exception to that rule, and it’s if the insulation is installed over another piece of insulation.
      Thanks for your question!

  37. I was insulating unheated garage below heated living space I live in PA and knew I had to get paper facing up (towards heated space). But couldn’t figure how since it cannot be stapled that way. After trial and error, I used Liquid Nails on understood of flooring above, pressed insulation paper against it about 12-16″ lengths at a time, then secured in place compressed tightly against the ceiling with an insulation hanger per 12-16″ section. The next day (after glue dried), I removed the insulation hangers and fluffed the insulation so it properly expanded and flushed against the bottom sides of the 2×6 joists. Hope this helps someone out there…

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