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-   -   Insulation Question...enough? (http://www.diychatroom.com/f19/insulation-question-enough-168304/)

brazosdog02 01-05-2013 11:48 AM

Insulation Question...enough?
 
I have an unfinished second story that already has insulation put in. I purchased the house this way. There is a kneewall, a cold cieling and a regular cieling with an attic. The roof is galvalume metal, with tech sheild decking. The roof rafters have R19 in them. They are cupped to allow air flow. Below them in the cieling is R13 insulation. The kneewall also has R13. The cold cieling has R19.

I have spoken to 15-20 different people online and in person about it, had a few contractors out, and I have yet to get any sort of concensus on what is correct or not. Im nearly at the stage now where im going to just finish off the rooms as is. My last insulation contractor says its MORE than enough and he would not add anything to it. If anything, he would finish it off, and then come out during the peak heat with a heat gun and see how the current setup is performing, and then go from there.

GBrackins 01-05-2013 12:12 PM

where are you located? insulation requirements are based upon your physical location.

brazosdog02 01-05-2013 12:21 PM

Texas, Houston Area.

brazosdog02 01-11-2013 10:34 AM

Still trying to get some info on this. In my cold cielings with 2x10 joists, can I just put in R19 and a thermal break for the drywall? I need to have a little space in there for either baffles or just airspace for ventilation.

tjbingha 01-11-2013 10:40 AM

http://energyhttp://energycode.pnl.g...s/?state=Texas

Take a look at this map. Per this it appears that R-30 is required. I would also think that you need to have this vented as well. I need R-30 where I am located and just had to put in 2 x 12's to accommodate the depth.

Good luck.

brazosdog02 01-11-2013 10:47 AM

Yeah, I see that, but im not sure if it comes to allow for 12" OC rafters. I won't be 'adding' 12" rafters, that's for sure. I think that will be OK, since the roof is metal AND has techshield decking under it. I figured all of that coupled with a metal stripping perpendicular to the joists would allow for a thermal break to the drywall and make it even better.

I meant to say that R19 is already between those cold cieling joists. The rest of the attic has R19 in the joists and R11 in the cieling, making R30 total. Its an unconventional install, but thats the way it was when I bought it and im not planning on pulling it all out.

tjbingha 01-11-2013 11:30 AM

Ok, I am guessing I am not understanding your question properly then. Unconventional, yes, but 19 + 11 does equal 30. Some of the experts on here should be able to tell whether that is right or wrong. I would think wrong, but then again I am not a licensed specialist. I would think the correct way would be to add R-30 in the ceiling and to take out the R-19. Again, far from an expert on this. Someone way smarter will answer in but it seems like it would allow too much of the cool air to escape into the cold ceiling.

"Yeah, I see that, but im not sure if it comes to allow for 12" OC rafters."

Get the 23 Inch batts and cut in half for your 12 inch O.C.

Good luck!

brazosdog02 01-11-2013 01:29 PM

No, you understand correctly, and you are correct, the R values don't add up like that....What I meant to put was that Im going to add insulation in my cieling on top of the R19 to get to R30. Im going to leave what's in the rafters, even though its not conventional....I cannot see any reason to remove it as it is if ventilation works. I just meant I have R30 worth of insulation between my cieling and roof rafters. What I need if R30 in the cieling alone.

tjbingha 01-11-2013 01:36 PM

Ok. After much back and forth we are finally on the same page! I think you would be able to do what you are doing without issue. I don't think that R-19 is bothering anything up there. I don't think it is doing any good either but oh well.

brazosdog02 01-11-2013 03:12 PM

My other concern is that there is a little angled cieling area that provides the air flow to my attic from my soffits way on the first floor. Now, that little angled cieling, or vaulted cieling, or cold cieling, or cathedral cieling.....goes like this from the outside to the inside: metal roof, decking with radiant barrier, air gap, R19 insulation, and then drywall...which is not up yet. This is a 2x10 roof rafter. Ive been told that R19 is enough since there is a radiant barrier. Is that true? technically, there i no way to get a full R30 in that space AND keep the required air space for ventilation without furring in down.

sweaty 01-12-2013 06:34 AM

If you don't seal the attic first, outside air will just leak right through insulation. Seal thoroughly first, then insulate.

brazosdog02 01-13-2013 10:16 AM

What are you talking about? There is nothing to seal. This is a vented attic.

:confused1:

sweaty 01-13-2013 01:38 PM

I should have been more specific. Seal the electrical and plumbing penetrations from the air-conditioned space into the attic, as well as any gaps in construction.

brazosdog02 01-13-2013 02:08 PM

Ah. Gotcha!!

brazosdog02 01-18-2013 11:01 AM

So, if I seal my rooms, will r19 in that cathedral ceiling be sufficient? Also, if I decide to use foam board on the rafters OVER THE EXISTING fiberglass batt insulation, should I remove the paper facing on the batts first or is it OK to put the foam board touching it directly?


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