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Attic air sealing, insulation identification, and best course of action

ChrisInIllinois | Posted in General Questions on

A full overview: bulit in 1975.
paneling walls, plastic sheeting, then r11 foil / Kraft facing interior.

Ceiling is 1/2 tile, furring strip, plastic sheet, ceiling joists. The ceiling tiles are completely throughout the house. 

Lose laid plastic in crawl space.

There was mold in attic that was remediated aka vent added cleaned up and white coating. Most likely due to normal air leaks + extra no paneling or tile behind and above kitchen cabinets, bath vented to attic… I have been busy need less to say.

There was a mouse issue too at some point, think it is all sealed up now.

So my questions?

(1) Is there going to be massive amount of air leakage from all the tile lines?

I plan to drywall but have a few other things to remedy first.

(1.1) was just wondering if trying to air seal penetrations in the Attic was worth it with the tile see the attached image.

(2)  based on above info should I try to save attic insulation / plastic  or just toss when all is fixed and replace?
Was thinking a solution could be 1 joist  Bay at a time, remove it all cobble in 1/2 inch foam, add back or add new insulation.

(3) can anyone identify the darker insulation? there is 3 types so far up there. There is not much of it, I’m just concerned it might be asbestos.

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  1. seabornman | | #1

    The darker stuff appears to be cellulose, the lighter fiberglass, so no asbestos. Unless the plastic sheet was expertly installed the ceiling will be tough to airseal. How much insulation is there in the attic and how much room to work? You could move insulation around as you go, but that's tough work. So is vacuuming out all of the existing or letting it fall to the floor. There are insulation companies who will remove and replace but it sounds like you don't want to do it all at one time.

  2. Jon_R | | #2

    You will get more results with less effort if you use a window fan + thermal camera to find the air leaks.

  3. GBA Editor
    Brian Pontolilo | | #3

    Hi Christopher.

    I would imagine that it would take some doing to air seal your tile ceiling, like your suggestion of cut-and-cobble between the joists. I had a ceiling like that and chose to take it down and replace it with drywall. Mine wasn't holding up insulation though.

    I've also seen remodels where they covered the tile ceiling with drywall, instead of taking it down. If you make the drywall continuous and use caulk where necessary, you'll do a lot of the air sealing with the drywall and minimize some of the work you need to do in the attic. And you may not need to remove the existing insulation, you may be able to add more on top of it.

    Also, it doesn't look like asbestos either, but if you are unsure, it's worth getting it tested to find out if you should be concerned with remediation. Do you know a qualified builder or remodeler in the area who could asses the situation and guide you on the best path?

  4. Expert Member
    BILL WICHERS | | #4

    If that plastic sheet above the tiles is continuous, that would be good air barrier provided it’s not damaged. It would be a good idea to check that there aren’t lots of holes, and seal any that you find. Proper attic ventilation will help too.

    I agree the darker insulation looks like cellulose and the yellow stuff is probably fiberglass. All the asbestos I’ve ever seen has been pretty bright white (unless dirty), or purple. I was warned the purple stuff is extra nasty.


    1. Deleted | | #7


  5. ChrisInIllinois | | #5

    There is a good amount of room to work (would be on knees) but for the last 4 feet near soffits. The joists are 2x6, they are covered plus some. so I would say 5.5 to 7 inches. It looks like it's Batts, then pouring fiberglass, then a thin layer of of dark stuff.

    There is 4 more bags of pouring wool (yellow fiberglass) up there lol.

    There is less than 1000 SQ foot of space to do.

    To Brain, qualified and builder do not belong in the same sentence around here. I would have to out source to a company hours aways. With the lack of code enforcement I would have to oversee the work myself too. It's crazy but I would gladly love a nice permit system with picky over the top inspectors. I quote from the last of 4 conversations with the nice gentleman in charge. "permits are only needed for new construction defined by extending or adding a new foundation. Then all you need is a bill of materials just for tax purposes. It's assumed you follow building codes."

    1. GBA Editor
      Brian Pontolilo | | #6

      Hi Christopher.

      That's unfortunate, but not surprising. Even in areas with inspections and lots of builders, it can be tough to find any who care enough to continue learning current best practices and make sure they are getting the important details right. So, it's great that you are taking the time to educate yourself and seek out info.

      I missed that some of the insulation was batts. The photos make it look like all loose stuff. If you do cover the existing insulation, check that the batts are well-seated in the joist bays and are in contact with the ceiling. I'm not sure if they shrink or what exactly happens, but I have seen old batts that are stapled into joist bays and seem to tighten up and pull away from the ceiling.

      Bill is right that the poly could provide a good air seal. I've never tried to install poly as an air barrier, but I've heard from lots of builders that it's too fussy to be worth relying on as an air barrier, which doesn't make me confident that yours would be providing a good air seal. It would take some testing to know for sure.

  6. ChrisInIllinois | | #8

    Is the old mouse / mold issues a problem for the current plastic or insulation? I know there was a few nasty mouse stains on some of the plastic in the Kitchen soffit ceiling area. I cut the plastic, weaved in new 6 mil, over lapped a foot and siga wigluv taped it before I put the cabinets back up. Aka drywall ceiling above them + drywall soffit + drywall for walls. The only "wall" in the kitchen was paneling for counter backsplash and behind refrigerator and stove. :( It's been fun.

    1. GBA Editor
      Brian Pontolilo | | #9

      As long as they have been cleaned up, and the problems that were causing them remedied, I don't think they are a problem for the materials and they are unlikely to be a problem for you and others who live in the home if the cleanup was done well. Either way, the health issue would depend on your personal sensitivities to such things as mold and feces.

  7. Expert Member
    Dana Dorsett | | #10

    >"can anyone identify the darker insulation? there is 3 types so far up there. There is not much of it, I’m just concerned it might be asbestos."

    Take a butane or propane torch to the insulation samples. If it melts or catches fire it's not asbestos , which had fallen out of use for residential insulation in most places by the mid-'70s, and banned for many purposes.

    >"Was thinking a solution could be 1 joist Bay at a time, remove it all cobble in 1/2 inch foam, add back or add new insulation."

    That would be a waste of time & effort. Air tightness at the ceiling level is far more important than vapor tightness at the ceiling, especially for a vented attic. Tossing it all and just doing a good job on the replacement ceiling's air tightness would be easier, and time better spent.

    1. Deleted | | #11


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