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Discussion Starter #1
When putting in new insulation in attic floor using fiberglass batts should I buy the paperfaced and have the paper facing towards the house side? I live in Long Island NY so so the winters can get cold here. Should the fiberglass extend past the top of the floor joists or should it be flush? What about Roxul can I use that? It dosent come with paper on it? Would that be ok to just put down between the joists? Or do I need to put down some kind of air barrier under neath it?
 

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In order of what you should do ,
Seal any place that air might leak from the house, wires coming up thru walls. holes around plumbing vent pipes and bathroom fan and kitchen fan ducts, ceiling lights.
Question anything you are not sure about, like how to seal door into attic.
Asses the venting low around the perimeter and high at or near the peak.
You can insulate above the level of the joists but you need to insure air flow from the soffits. Paper backed is not all that important if you have sealed all the air leaks.
I would think a loose fill insulation would be better than any type of bats.


Bud will be along with more detail, it is his thing.
 

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Hi Moe, just getting here.
Neal covered it very well, vapor barriers have basically been replaced by detailed air sealing. In addition to the penetrations Neal listed the tops of all walls below provide a paper thin leak between the drywall and framing. Big leaks are far more important but some well placed caulking when the opportunity is there doesn't hurt.
Here is a link on air sealing all over the house.

So, just drop the Roxul in, be neat, and you will be fine. Be sure to not block the air flow from the soffits.

Bud
 
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We Have a Sprayable foam installation. If you can do that I would recommend it. It will seal any drafts that you might get coming from your walls and will last longer then fiberglass and in my opinion it is healthier. I hope I have been helpful.
 

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Discussion Starter #5
In order of what you should do ,
Seal any place that air might leak from the house, wires coming up thru walls. holes around plumbing vent pipes and bathroom fan and kitchen fan ducts, ceiling lights.
Question anything you are not sure about, like how to seal door into attic.
Asses the venting low around the perimeter and high at or near the peak.
You can insulate above the level of the joists but you need to insure air flow from the soffits. Paper backed is not all that important if you have sealed all the air leaks.
I would think a loose fill insulation would be better than any type of bats.


Bud will be along with more detail, it is his thing.

Thanks for the reply, what do i seal with around all the ducts, wires, lights? Do i use the fireblock foam?
 

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Discussion Starter #6
Hi Moe, just getting here.
Neal covered it very well, vapor barriers have basically been replaced by detailed air sealing. In addition to the penetrations Neal listed the tops of all walls below provide a paper thin leak between the drywall and framing. Big leaks are far more important but some well placed caulking when the opportunity is there doesn't hurt.
Here is a link on air sealing all over the house.

So, just drop the Roxul in, be neat, and you will be fine. Be sure to not block the air flow from the soffits.

Bud
Hey Bud so are you saying that thE paper backing on the sheetrock acts as an air barrier and as long as I seal everything like Neal suggested I should be fine just putting in the roxul? From what I’ve been reading for the most part people say its a much better insulation to use than fiberglass, I just wasent sure if its adequate for attic floor (my living space ceiling) and warm air traveling up into my cold attic and making contact with the unfaced insulation and causing moisture/mold issues up there. I’m not using it as a living space but I want to avoid having mold forming in my house. Thanks for the link Its has tons of useful information.
 

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Discussion Starter #7
We Have a Sprayable foam installation. If you can do that I would recommend it. It will seal any drafts that you might get coming from your walls and will last longer then fiberglass and in my opinion it is healthier. I hope I have been helpful.

Thanks Burke I’ve heard about the spray insulation but it seems to be on the expensive side and I think this is a project I’ll be doing myself to save $$$$
 

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I just wasent sure if its adequate for attic floor (my living space ceiling) and warm air traveling up into my cold attic and making contact with the unfaced insulation and causing moisture/mold issues up there.
With decent detailing of the air seals in the places mentioned, there shouldn't be too much air leakage. Roxul aka Rockwool will also slow any air leaks (at least more than fiberglass would). Any warm/moist air that gets past that will just vent out the roof through the ridge vent as intended.
Also not sure if the previous poster was recommending a full closed cell spray foam application or just to use the canned stuff at the gaps. There is a whole arsenal of sealing products that are useful from caulking little moving gaps, to foaming bigger ones, to exotic sealing tapes from Europe. Go check out https://www.greenbuildingadvisor.com for more info than you'd ever need to know!
 

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Discussion Starter #9
With decent detailing of the air seals in the places mentioned, there shouldn't be too much air leakage. Roxul aka Rockwool will also slow any air leaks (at least more than fiberglass would). Any warm/moist air that gets past that will just vent out the roof through the ridge vent as intended.
Also not sure if the previous poster was recommending a full closed cell spray foam application or just to use the canned stuff at the gaps. There is a whole arsenal of sealing products that are useful from caulking little moving gaps, to foaming bigger ones, to exotic sealing tapes from Europe. Go check out https://www.greenbuildingadvisor.com for more info than you'd ever need to know![/QUOTE]

Thank you uncle Bob i will start with the leaks first n see what i can seal up there to keep the warm air downstairs in my living space
 
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