Attic w/Blown In Insulaion W/O Vapor Barrier


Old 04-01-03, 08:42 AM
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Unhappy Attic w/Blown In Insulaion W/O Vapor Barrier

I have a home in North West NJ (07882) that has blown in insulation in the attic, but no vapor barrier. There are also no baffles in the rafters and in many cases the blown in insulation is covering most of the area in front of the eaves.

I noticed this winter that boards laying on top of the insulation had ice on the underside. That started me thinking that not having a vapor barrier is causing a moisture problem in the attic.

My plan was to remove the blown in insulation, add baffles and re-insulate. What I am finding is that because my roof is relatively low (can only stand in crouched position under the peak and can only get within two feet of the eaves laying down) that it is hard to move the blown insulation from the edges of the joists to the center of the attic. The other problem is that there is a lot of loose insulation to deal with.

I am starting to think I would be better off clearing a portion of the attic of the blown insulation, adding a baffle under the joist, putting down a faced fiberglass batt (face down) and then moving the lose insulation back in place.

-Can I move loose insulation out of an area and just move it back (with a broom for example) or does it need to be blown back in place?

-Much of the pink blown in insulation is discolored dark gray. Could this be mold from not having a vapor barrier?

-Any suggestion for removing the blown in insulation if I still wanted to go that route? I have called all the local insulation contractors and they only add insulation, they don't remove it.
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Old 04-01-03, 12:42 PM
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The pink blown-in insulation is apparently fiberglass insulation. The changing of this to a dark color grey indicates air movement in those particular areas where found. The fiberglass acts as an air filter as air moves through it. It catches the dust in the air and traps it in the insulation causing this dark grey discoloration.

There are 2 telltale signs if it were mold and/or mildew. One is the insulation would be compacted or feel compressed. The other is that mold and mildew gives off a distinctive odor.

Wood flooring over fiberglass insulation usually will develop moisture on the wood where the 2 meet. This is not a result of not having a vapor barrier or inadequate ventilation. This is a perfect example of different materials (fiberglass and wood flooring) abilities to absorb and expel moisture differently. It is these differences that condensation formed there. More than likely and in most cases when the temperature in the attic rose and thawed out the condensation, the moisture would be absorbed by the air in the attic and your attic vents would then remove it from the attic.

Out of the things you mentioned the only one that concerns me is the dark colored grey spots in the insulation. If the air movement is coming from inside the home, then you have air transported moisture. Neither a vapor barrier or attic ventilation pertains to the prevention and/or control of moisture with air transported moisture. The incidence of mold and mildew is considerably higher with air transported moisture than heat transported moisture within structures.

Where you find these spots, pull back the insualtion and most likely you will find an electrical wire penetrating the attic floor to the room below, plumbing stacks, recess lighting, telephone and/or TV cables, etc. Buy a can of foam and foam up the holes.

I am not recommending that you remove the insulation to install the baffles because you probably have good ventilation. Considering the winter we had in NJ this year, you would be complaining about ice damming and damage and not some frozen condensation under the flooring. Furthermore, inadequate ventilation is usually apparent throughout the entire attic like all the roofing nails would have discoloration around them. In some cases if not most there is a discoloration on the underside of the roof.
Old 04-01-03, 01:01 PM
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Thanks for your reply. Like I inidcated I have already moved the majority of the insultaion away from the outter portion of my attic.

In many cases there were electric wires or vent pipes in the areas of the dark insulation. I agree that the blown in insulation is fibergalss. I didn't notice any odors other than dusty attic smells.

Since a good portion of the insulation has been moved I am really looking for how to proceed. I will install baffles, fill the holes with foam and put faced fiber glass insulation in the joists.

Once all of that is done can I just sweep the fiberglass insulation back into place or should I remove it and put unfaced insulation on top of and perpendicular to the faced insulation that I will have put in the joists?
Old 04-01-03, 02:16 PM
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If you are laying down faced fiberglass insulation, you can put the blown-in insulation on top of that.

If you put back the blown-in insulation then want to add more but the batt type, then the fiberglass insulation has to be unfaced. Because the blown-in insulation is first, it doesn't matter if you lay the insulation parallel or perpendicular to the floor joists.

Either application is fine.
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