# Insulation Dilema- Vaulted/Cath. Ceiling



## JLOC (Dec 11, 2007)

i am hoping to get some feedback on the issue I have found in my house while redoing our dining room. The electrical issues that can be seen in the photo's are one of the reasons I pulled the drywall to begin with and are being corrected. My dilemma at the moment is how to properly insulate this area of the house.

The roof/ceiling is 2x4 construction and pretty much "Non Vented" (to the outside of the house anyway). Whoever re drywalled this room at sometime before I owned the house installed FG insulation in some places and none in others. It was poorly done. The drywall is chalky and feels dried out. I am going to pull the rest down and redo it all but my dilemma lies in how to insulate this area the right way.

In this photo it shows the lower side of the room. The wall joins the dining room and our garage... Sooo obviously not vents here.

http://craftwerks.smugmug.com/Other/Random/i-jCFkv3p/0/M/IMG1221-M.jpg

In this photo, It shows the higher side which shares the wall with out kitchen. There is no blocking and it is open to our attic space.

http://craftwerks.smugmug.com/Other/Random/i-ZmnmWMx/0/M/IMG1220-M.jpg

Here is an overall shot of the ceiling.

http://craftwerks.smugmug.com/Other/Random/i-7QC35LD/0/M/IMG1222-M.jpg

Here is the adjacent room that is also vaulted. This has been poorly insulated as well (from the inside and covered with bead board) and is going to get redone. This room has 4x6 beams, T&G for the ceiling.

http://craftwerks.smugmug.com/Other/Random/i-VhDzPjF/0/M/IMG1223-M.jpg

My plans are to have it insulated from the outside when we redo our roof so that we can leave the beams and T&G exposed. 

I am in Southern California FYI.


Any input would be much appreciated!

Thanks in advance!


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## gregzoll (Dec 25, 2006)

Can you post a outside shot from roof level, then one from the ground also, so that people can get an idea of what the roofline looks like. If it was me, and I was going to do it correctly, I would be going with spray foam on the roof.


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## JLOC (Dec 11, 2007)

gregzoll said:


> Can you post a outside shot from roof level, then one from the ground also, so that people can get an idea of what the roofline looks like. If it was me, and I was going to do it correctly, I would be going with spray foam on the roof.



Will try and get a few pics showing the ext. in a bit. 

Thanks.


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## JLOC (Dec 11, 2007)

Here is a shot of the roofline.

The lower level to the left is the garage.


http://craftwerks.smugmug.com/Other/Random/i-3CnWwfh/0/M/Image-M.jpg


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## gregzoll (Dec 25, 2006)

Standard roofline, I would treat it as that. If it was vaulted, then yes insulate outside, but in this case, insulate the bottom side, maybe reflective foamboard with the foil facing the sheathing.


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## JLOC (Dec 11, 2007)

Thanks for the reply....

Will I not have to worry about any condensation build up as it is a non vented area of the roof? 

Should I go as thick as possible on the foamboard or no?


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## gregzoll (Dec 25, 2006)

I would still vent the space. When spray foam is used, or the reflective foam board is used, it then creates a thermal break.


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## JLOC (Dec 11, 2007)

Venting isn't much of a possibility.... As I mentioned above, The lower side of the room shares a wall with the garage so there is no way to have incoming air from the outside. The high side I could leave open to the attic but no way to vent to exterior.


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## Windows on Wash (Aug 30, 2011)

JLOC said:


> Venting isn't much of a possibility.... As I mentioned above, The lower side of the room shares a wall with the garage so there is no way to have incoming air from the outside. The high side I could leave open to the attic but no way to vent to exterior.


You can probably drill some cross over holes in the rafters (as long as they don't weaken the structure) to get some air over to those rafter bays.

You could also rip some kirf cuts in the foam if you are going to apply that over the rafters to allow some cross over ventilation.

What is the garage like? Attic or vaulted?


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## JLOC (Dec 11, 2007)

The garage does not have an attic space. It is exposed 2x4 framing like this room except it is not insulated or drywalled.


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## Windows on Wash (Aug 30, 2011)

Vent that section of the garage where it connects via the eaves and close off those few rafter bays with drywall to prevent it pulling air from the garage.


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## JLOC (Dec 11, 2007)

Windows on Wash said:


> Vent that section of the garage where it connects via the eaves and close off those few rafter bays with drywall to prevent it pulling air from the garage.


Thanks, I will look into that... That very well might be an option.

Any any ideas, thoughts on leaving it closed and spraying foam?


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## Windows on Wash (Aug 30, 2011)

I would probably go with greg's recommendation of rigid foam with a foil facer and vent the roof.

You are not too worried about heat loss of there and thermally breaking the roof assembly would go along way to helping with the cooling and heating load.


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## Gary in WA (Mar 11, 2009)

Where are you located in S.Cal.? There are 3 zones there; http://publicecodes.citation.com/icod/irc/2009/icod_irc_2009_11_sec001_par001.htm

No foil-faced foam board on the rafter bottoms in your location, especially if you run AC, the rafters will rot without ventilation.

Gary


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## JLOC (Dec 11, 2007)

GBR in WA said:


> Where are you located in S.Cal.? There are 3 zones there; http://publicecodes.citation.com/icod/irc/2009/icod_irc_2009_11_sec001_par001.htm
> 
> No foil-faced foam board on the rafter bottoms in your location, especially if you run AC, the rafters will rot without ventilation.
> 
> Gary


Gary,
I am in 3B. (los angeles) was the closest they listed.


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## Windows on Wash (Aug 30, 2011)

GBR in WA said:


> Where are you located in S.Cal.? There are 3 zones there; http://publicecodes.citation.com/icod/irc/2009/icod_irc_2009_11_sec001_par001.htm
> 
> No foil-faced foam board on the rafter bottoms in your location, especially if you run AC, the rafters will rot without ventilation.
> 
> Gary


+1

Venting was specified by both Greg and me in this case. Your details need to be spot on in this case and if you change the dynamics of that space, you need to make sure you are not creating and issue for certain.

The reality is that the skip sheathing in that roof probably moves a bunch of air from the bottom to the top which is probably why you haven't had any issues previously.


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## JLOC (Dec 11, 2007)

I dont think I have left out any details to be not spot on...... I appreciate all the feedback, I'm just trying to figure the best solution for this.

I have been researching this all day today and still not sure where I stand.


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## Gary in WA (Mar 11, 2009)

I saw information to foamboard the bottom side of the rafters, or understood it that way, at least. 
With a vented roof, which you sort of have, as WW said- the skip sheathing boards allow air movement- especially sideways, I wouldn't want foamboard on the bottom side because it is a Class 2 vapor retarder. You have a vapor retarder on the top side already- the builders felt/paper under the shakes. Running your AC would pull some hot moist air in through the roof to equalize the pressure difference of the room, that couldn't be made up elsewhere, depends on how well-vented the roof really is. (It may be fine, I don't know without a blower-door/smoke test).

If it was an unvented assembly, the foamboard would install tight to the roof sheathing to be an air barrier, leaving room for shake. Then add permeable insulation (if even needed in your location). http://resourcecenter.pnl.gov/cocoon/morf/ResourceCenter/article/1520

Gary


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## JLOC (Dec 11, 2007)

I'm guessing that our roof isn't vented well... by todays standards anyway. It is a 1950's california ranch style home, approximately 2000Sq.ft. and has no soffit vents what so ever, Only 4 gable vents


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## JLOC (Dec 11, 2007)

GBR in WA said:


> I saw information to foamboard the bottom side of the rafters, or understood it that way, at least.
> With a vented roof, which you sort of have, as WW said- the skip sheathing boards allow air movement- especially sideways, I wouldn't want foamboard on the bottom side because it is a Class 2 vapor retarder. You have a vapor retarder on the top side already- the builders felt/paper under the shakes. Running your AC would pull some hot moist air in through the roof to equalize the pressure difference of the room, that couldn't be made up elsewhere, depends on how well-vented the roof really is. (It may be fine, I don't know without a blower-door/smoke test).
> 
> If it was an unvented assembly, the foamboard would install tight to the roof sheathing to be an air barrier, leaving room for shake. Then add permeable insulation (if even needed in your location). http://resourcecenter.pnl.gov/cocoon/morf/ResourceCenter/article/1520
> ...


I am also thinking that because of the skip sheathing It might be providing "Some" air flow and with it being in Southern Ca. and our pretty stable weather ( No snow ) that it could be why we haven't had a major issue.

Any advice on whether I should wait until we get our roof done and then deal with making this right?


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## Gary in WA (Mar 11, 2009)

I'd wait on the insulation (as I look out the window at 7" of snow) and work on the electrical. That j-box is supposed to be exposed, accessible from the room, an outlet box, etc..... some sharp "sparkys" in our electrical section.

Gary


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## JLOC (Dec 11, 2007)

GBR in WA said:


> I'd wait on the insulation (as I look out the window at 7" of snow) and work on the electrical. That j-box is supposed to be exposed, accessible from the room, an outlet box, etc..... some sharp "sparkies" in our electrical section.
> 
> Gary



lol..... Yea, I was thrilled when I pulled the drywall and found all that goodstuff!

Just glad I found it now before it was too late and something bad happened. Still blows my mind that people will do such horrible work.

The electrical is no problem to fix and get right, it's all this insulating nonsense that has me all worked up. LOL.


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## Gary in WA (Mar 11, 2009)

Least you have time before the snow comes......LOL.

Gary


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## JLOC (Dec 11, 2007)

So I have had two roof estimates so far, and both contractors suggested foam board with ply on the exterior directly over the T&G. Non ventilated. I have one more estimate coming tomorrow so we will see what process they recommend. So If I go solid foam on the exterior, I just need to figure out what to do inside to insulate it properly in the dining room where drywall will be installed.


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## JLOC (Dec 11, 2007)

So I have been busy with work and a gathering estimates and info in the last few weeks, but I think I have a plan now with all the info that I have collected.

At this point, We are planning on doing the following:
Install rigid ( have not decided on which kind or thickness) insulation on the outside when we do our roof, and R-13 batt's in the rafter bays and finished with drywall on the inside. Non vented.

Sound like I am on the right track?


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