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-   -   Insullation in 2nd floor ceiling - yes or no? (http://www.diychatroom.com/f103/insullation-2nd-floor-ceiling-yes-no-187944/)

twincharged rx7 10-02-2013 03:59 PM

Insullation in 2nd floor ceiling - yes or no?
 
Hi all,

I'm about to re-insullate my whole house (all walls and ceilings /studs and joists are exposed now).

My attic roof is insullated (2x6 rafters, not sure what type of insullation is in there, its not fiberglass, its grey and has a brittle paper holding it all up against the rafters and roof sheathing).

The second floor ceiling was not insullated previously (house was built in 1925). Should I go ahead and insulate the second floor ceiling with R19? I have 2x6 joists.

The attic is not a living space, its just for storage.

I think extra insullation would be great, but not sure about vapor barriers. If I have insullation already in the attic roof, do I want insullation and then a vapor barrier before I sheetrock the 2nd floor ceiling.

I don't see any kind of vapor barrier on the attic insullation aside from the paper facing.

Just don't want to go ahead and add insullation and vapor barrier and then end up with some kind of problem.

The roof looks to be a ridge ventilated type (roof was done 2 years ago, prior to me owning it). I'm assuming this because I do not see any vents near the eaves (i removed a little of the old insullation to take a peek).

I live in Northern NJ, so I do get a winter.

Gary in WA 10-03-2013 11:39 PM

R-38, minimum code; http://energycode.pnl.gov/EnergyCode...e=New%20Jersey

No insulation between living space floors. If you cannot meet code minimum ventilation rates, go unvented attic; http://www.buildingscience.com/docum...on?full_view=1

Zone 5; http://www.buildingscience.com/docum...rchterm=attic+

Imperative to air seal the attic first; http://www.buildingscience.com/docum...sealing-guide/

Gary

HomeSealed 10-04-2013 02:25 PM

Expounding on Gary's comments, the ideal situation would be to remove the insulation from the underside of the roof deck, and the air seal and insulate the attic floor/2nd floor ceiling to code (I prefer r50). Currently you are essentially bringing your attic into the building envelope and wasting energy. This would correct that, although it would be at the expense of your storage area... Gotta pick what is more valuable to you.

SPS-1 10-04-2013 04:11 PM

Quote:

Originally Posted by HomeSealed (Post 1249476)
the ideal situation would be to remove the insulation from the underside of the roof deck, and the air seal and insulate the attic floor/2nd floor ceiling to code (I prefer r50).

But this would also require adding soffit vents, so the attic is properly ventilated, right?

twincharged rx7 10-04-2013 05:52 PM

Thanks for all the info. Based on that website, I have an invented roof, which is ok for my climate as long as the insulation and air barriers are correct

Also, I can't need code if I rip out the insulation under the roof deck, as I only have 2x6 joists on the second floor and the attic has floor boards, so I can't just throw down a ton of insulation.

Ill be going with insulation in the 2x6 joists and a vapor barrier. Ill also keep the existing insulation under the roof deck.

Unless of course someone has seen this fail and result in extra moisture.

On the website linked to they actually say its better for my air handling equipment (more efficient) if the attic is enveloped into the house (insulation under the roof deck)

Gary in WA 10-05-2013 02:03 PM

Either vent the attic or not. When not, you need foam (spray) or foam board next to the sheathing as that link brought out. See the map and read the whole article, her; http://www.buildingscience.com/docum...n-roof-venting

http://www.buildingscience.com/docum...ation-packages

Gary

HomeSealed 10-05-2013 03:43 PM

Quote:

Originally Posted by twincharged rx7 (Post 1249541)
Thanks for all the info. Based on that website, I have an invented roof, which is ok for my climate as long as the insulation and air barriers are correct

Also, I can't need code if I rip out the insulation under the roof deck, as I only have 2x6 joists on the second floor and the attic has floor boards, so I can't just throw down a ton of insulation.

Ill be going with insulation in the 2x6 joists and a vapor barrier. Ill also keep the existing insulation under the roof deck.

Unless of course someone has seen this fail and result in extra moisture.

On the website linked to they actually say its better for my air handling equipment (more efficient) if the attic is enveloped into the house (insulation under the roof deck)

That i sfine if that is route that you want to go. Like I said, pick where you want the envelope to be, it would be incorrect to try and do both. Th efloor boards would get ripped up, or dense packed and then loose fill blown over if you wanted to go that route, otherwise if you prefer to condition the attic then follow Gary's links.


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