Knee wall questions

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  #1  
Old 10-26-15, 09:40 AM
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Knee wall questions

Hey guys,

I have a standard bonus room over garage with knee wall attic space on both of the adjacent walls. As seen in the pictures, only the interior walls are insulated but they are not sealed (foam board, drywall, etc). Should they be? And if so which would be ideal with cost being of normal concern?

Also, should I add/continue the air baffle (not sure the correct name) from the top of the sloped ceiling all the way down to the exterior soffit and then cover the baffle & ceiling with batt insulation? Or leave the baffles where they are and just add insulation?

Is R30 batt insulation sufficient for middle TN or do I need to use R38 or better?

Sorry for all of the noob questions but I'm, well, a noob





 

Last edited by 1st Cav; 10-26-15 at 10:11 AM.
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  #2  
Old 10-26-15, 09:48 AM
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  #3  
Old 10-26-15, 10:07 AM
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The link below may help with some of your questions. I will wait for the pictures.

One concern may be living space over a garage. It is very important to air seal and provide the code required thermal barrier.

Bud
 
  #4  
Old 10-26-15, 10:12 AM
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Thank you sir! Your help is greatly appreciated
 
  #5  
Old 10-26-15, 10:55 AM
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Pictures added! Any thoughts?
 
  #6  
Old 10-26-15, 12:01 PM
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Can someone at least tell me if the information provided in this link is legitimate and should be followed? If so, I'll just use it as a point of reference

http://www.finehomebuilding.com/pdf/021230088.pdf
 
  #7  
Old 10-26-15, 12:02 PM
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Article seems to contain good information at quick glance.
 
  #8  
Old 10-27-15, 03:49 PM
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LOL, the link I forgot to include in my post is a duplicate of your link. Very good information and I like the illustrations although I'm guessing yours is not exactly the same as their cape. Your side attics have a kneewall and rafters that extend down to a half wall, is that correct?

At the distant end of the first picture, is that open to the garage, foil faced insulation reflecting the light or what?

The second picture with the baffle and insulation, where is that located, kneewall looking up, or high attic looking down?

4th picture, note the dirty insulation. That indicates air is flowing through the insulation instead of through the baffle.

Is the first picture the actual kneewall in question, with living space on the other side?

That will get us started.

Bud
 
  #9  
Old 10-28-15, 08:11 AM
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"Your side attics have a kneewall and rafters that extend down to a half wall, is that correct?"

Yes, they extend down from 4'9" down to roughly 30"

"At the distant end of the first picture, is that open to the garage, foil faced insulation reflecting the light or what?"

I'm not 100% sure what you mean by "open to the garage" but that is the exterior wall which faces my backyard, it is also one of the garage walls. And yes, any light you see is a reflection of my cameras flash

"The second picture with the baffle and insulation, where is that located, kneewall looking up, or high attic looking down?"

Kneewall looking up

"4th picture, note the dirty insulation. That indicates air is flowing through the insulation instead of through the baffle."

Does that mean I should replace all of that insulation because its dirty? I've also been curious of whether or not I should add batts of insulation to that sloped ceiling/rafter and extend the baffle down to the soffit

"Is the first picture the actual kneewall in question, with living space on the other side?"

Yes it is the kneewall in question with my bonus room on the other side. There is another kneewall with attic entry on the opposite side of the room with the same setup....but slightly worse (water heater pex lines, cables, and bonus room a/c unit return). I'll try to take pics of that side also.

Thanks
 
  #10  
Old 10-28-15, 08:28 AM
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I'm getting the picture, thanks.
I'm headed outside, now that the morning frost has melted, and going up 20' to finish the siding on the peak of a of my house. Moving the staging around is the toughest part at my age.

I will be back later as the rain moves in and add more here.

Bud
 
  #11  
Old 10-28-15, 09:11 AM
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Be careful up there Bud

This is the other kneewall attic space on the opposite side of the bonus room. First pic is a direct view into the space from the door (not sure what the black stuff is...tar paper?)



Left side view









When you walk into the door and look to the right this is what you see


Continuing to the right
 
  #12  
Old 10-30-15, 07:04 PM
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Bud

I hope everything went well for you with the siding project. Have you had an opportunity to look over and diagnose my attic problem?
 
  #13  
Old 10-30-15, 08:46 PM
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Still alive. Siding went well and staging will be moving tomorrow.

I still need to review the thread and see where we are, but a couple of questions.

What is that box we see in the second side attic? Does it need to be insulated?

Also, I see the short exterior wall that the rafters rest on has a top plate, but I don't see a bottom plate which raises the question, how is that wall built? Does the short section of wall we see extend down as part of an exterior wall for the garage below?

Bud
 
  #14  
Old 10-31-15, 03:00 AM
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The best description I can give for the box on the second side is that it's an exhaust/return vent for the a/c unit in my bonus room. It seems to be sealed off well so I'm guessing the answer to that question is no it doesn't need to be insulated.

Yes, the short exterior wall extends down as part of an exterior wall for the garage below. On the first attic side, the actual garage door is below and on the second side is an exterior wall
 
  #15  
Old 10-31-15, 04:44 AM
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It sounds like the framing for that wall is a version of what we call "balloon construction. Look or probe down those cavities to see if there is a fire block, a piece of wood completely blocking potential air flow. If all you find is an empty cavity or just insulation we will need to decide how to deal with that.

Also, what is under that plywood floor in the side attics. The current kneewall insulation, if you continue to go with that approach, needs full insulation under there.

Tell us what is in place for soffit and roof ventilation. I'm assuming there are ventilated soffits at the end of those rafters, then a ridge vent of other high vent above the slope.

Sorry to be so confusion, but it is difficult to see what the builder had in mind.

Still busy, but I will be back. Others may jump in and comment as well.

Bud
 
  #16  
Old 10-31-15, 02:27 PM
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I'm currently out of town and won't be back until tomorrow night but I distinctly remember the majority (90%) of those cavities being empty.

What's underneath the plywood floor is anybody's guess as of right now. I'll have to pry up a section when I get home to give you an honest assessment.

Yes, the soffit is ventilated and there are styrofoam ridge vents at the end of each opening
 
  #17  
Old 11-02-15, 04:09 PM
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Ok, just got in and immediately went to work in the attic space. I've verified that in attic #1 (first pictures I added to this thread) there is a long "header" that runs the length of the garage door, and on each side of that header there are two stud spaces (16 inches apiece) that are empty all the way down to the ground. In attic #2, every stud cavity is empty all the way down to the floor except one, and it has a 36 inch "header". That one is the other single exterior door that goes out of the garage to the backyard.

I also cut a hole into the attic floor to verify what was beneath. As you can see from the attached pictures, the width of the attic floor has no insulation below, but where the interior bonus room vertical wall begins is where the insulation begins and runs the length of the bonus room floor. So from what I can gather, the 14ft width of the bonus room floor is insulated (which makes sense because my feet have never been cold or warm before while in the room) but the adjoining attic space floors are not.


[IMG][/IMG]


[IMG][/IMG]
 
  #18  
Old 11-02-15, 07:03 PM
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Ok, so those cavities are essentially the garage walls open from garage floor level to side attic and uninsulated. The problem is they don't meet fire codes because they are providing an air path all the way up to the top of the roof, (except for those that are blocked by headers). Where insulation for the garage walls would be optional, a fire stop at the top where those wall cavities open into the side attic is not. A piece of 2x4 cut to size and sealed with a fire rated caulking is required. Insulation or rigid foam would not meet code.

In the first picture of the last two I see a piece of fiberglass insulation, but not a cavity extending across a 14' room. But from your explanation, the floor of that room is insulated with what is shown in the picture. It should have been more, but more importantly, there should be an air block below the kneewall on each side to prevent cold air from circulating in under that floor. The link you referenced illustrates that solid block below the kneewall. Comfort and energy issue, not a fire code.

Bud
 
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