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  1. #1
    john scott's Avatar
    john scott Guest

    Default attic knee wall insualtion

    Hello everyone,

    First,, Someting is not right with the insulation section of the forum. It will not display the post after one is selected. I am posting here and hope someone can move my post over if the system will work. In the meantime

    I have an issue with the vertical knee walls in relation to the vaulted ceiling. I just had the home re-insulated and it is no different than before. The insulation on the angular portion are only 1.5 inches because of the 2x4 of the truss and it does not reach the top og the wall.

    The company laid a fiberglass batt on the ceiling area and then blew insulation up to it but where the batt and the wall insulation meet i can still see the top cord and some drywall. They want to come back and pin the scrim sheet to the cord but it will result in zero insulation at this that point. I was under the impression they would run the scrim 13inches higher than the ceiling drywall and then blow insulation up against that.

    Either way,, I have been looking for a decent write up on the correct way to do this wall. All i know is what I have now is wrong. My ceiling pops some and i think it is a result of the temperature difference. I am selling this home in the near future and would like it to be correct for the next owner.

    Also, I have soffit vents that use the entire opening of my top 2x6 cord. (22.5x5.5). I believe they installed the cheapest cardboard baffle and I can not get an answer from the company as to the net free area or if I have deduced my flow. If they have put these in an inch from the plywood would that cut my flow by 80%. should there be a submittal somewhere for the product??

    Any help is appreciated,
    Thanks,
    Chris


    Here are some pictures;

    NHIE Practice Exam

  2. #2

    Default Re: attic knee wall insualtion

    Can you provide photos from further back, the photos make it difficult to understand the context.

    Jeff Zehnder - Home Inspector, Raleigh, NC
    http://www.jjeffzehnder.com/
    http://carolinahomeinspections.com/

  3. #3
    Join Date
    Feb 2009
    Location
    Southern Vancouver Island
    Posts
    4,546

    Default Re: attic knee wall insualtion

    What I expect to see here is Fiberglass batts attached somehow to the vertical areas. You are correct to call for repairs to what they did there.

    Re: soffit ventilation, sometimes a narrow slot is sufficient, if there are enough baffles and roof vents. It depends on the attic, the location, roof style, lots of factors.

    John Kogel, RHI, BC HI Lic #47455
    www.allsafehome.ca

  4. #4
    Bob Spermo's Avatar
    Bob Spermo Guest

    Default Re: attic knee wall insualtion

    After they fix the poor insulation installation they should install an air barrier.


  5. #5
    Join Date
    Aug 2007
    Location
    Memphis TN.
    Posts
    4,311

    Default Re: attic knee wall insualtion

    Quote Originally Posted by john scott View Post
    Hello everyone,


    I have an issue with the vertical knee walls in relation to the vaulted ceiling. I just had the home re insulated

    Any help is appreciated
    Quote Originally Posted by Jim Abram View Post
    John - The installation does not comply with code-

    IECC table R 402.4.1.1 and R 402.4.1.2

    It is a simple write up.
    Jim,

    Chapter 4 - Residential Energy Efficiency

    How is this suppose to help OP Home owner?

    How can you tell the Exterior Thermal Envelope is not house wrap applied under the cladding?

    Simple!!

    It Might have Choked Artie But it ain't gone'a choke Stymie! Our Gang " The Pooch " (1932)
    Billy J. Stephens HI Service Memphis TN.

  6. #6
    Join Date
    Apr 2014
    Location
    FL, TX
    Posts
    137

    Default Re: attic knee wall insualtion

    Quote Originally Posted by john scott View Post
    Hello everyone,

    First,, Someting is not right with the insulation section of the forum. It will not display the post after one is selected. I am posting here and hope someone can move my post over if the system will work. In the meantime

    I have an issue with the vertical knee walls in relation to the vaulted ceiling. I just had the home re-insulated and it is no different than before. The insulation on the angular portion are only 1.5 inches because of the 2x4 of the truss and it does not reach the top og the wall.

    The company laid a fiberglass batt on the ceiling area and then blew insulation up to it but where the batt and the wall insulation meet i can still see the top cord and some drywall. They want to come back and pin the scrim sheet to the cord but it will result in zero insulation at this that point. I was under the impression they would run the scrim 13inches higher than the ceiling drywall and then blow insulation up against that.

    Either way,, I have been looking for a decent write up on the correct way to do this wall. All i know is what I have now is wrong. My ceiling pops some and i think it is a result of the temperature difference. I am selling this home in the near future and would like it to be correct for the next owner.

    Also, I have soffit vents that use the entire opening of my top 2x6 cord. (22.5x5.5). I believe they installed the cheapest cardboard baffle and I can not get an answer from the company as to the net free area or if I have deduced my flow. If they have put these in an inch from the plywood would that cut my flow by 80%. should there be a submittal somewhere for the product??

    Any help is appreciated,
    Thanks,
    Chris


    Here are some pictures;


    Definitely not to code. Anywhere that there is drywall must be insulated and sealed properly. Also the horizontal 2X4s you are showing must be covered with insualtion completely to the same thickness as any other area in the attic. This wood is a thermal bridge and the insultion should be designed to keep the wood from getting hotter or colder as well.

    I am glad to see you used thermal reflective barrier. This is an excellent thing. Your profile does not indicate your location. If you are in lets say Texas where it can get cold for weeks and very hot, I suggest the complete attic envelope be reflective barrier. If in the north where winters are cold and summers moderate overall, I suggest overlay on the insulation only. If in the south such as Florida where winters are moderate and the sun is brutal, I suggest reflective barrier only under the rafters (creating a shade tree over the entire house in essence.

    If your barrier is under the rafters and installed properly (this would include any "walls" in the attic facing south, east or west where the sun gets really hot) the difference between outside shaded ambient temperatures and attic temperatures would likely be within about 3 degrees if the work was performed properly and vented properly (I have installed many in Texas with this numbers close to 3 degrees ambient)

    Regarding the venting: There are codes regarding minimum vented area ( I have seen some variation in localities, but generally all the same. Your soffit vents must have at least that much area relative to attic volume. Where the soffit vents can allow air flow to the opening above your insulation, the total area that the cardboard relieved can not be less than that required for the total vent area. This would be fairly easy to estimate. By measuring a few. Remember that each soffit vent has a percentage open area by design. A 12 X 4 (48 sq inches) soffit vent with 50% open area would be 24 square inches open. Remember if you do not have proper venting in the top 1/4 of the attice, air will not move anyway, so check to see that the ridge vents or gable vents are to code in area as well. I have had to add soffit vents in many installations as well as roof or gable vents to create proper air flow. Also if your soffit vents are not fairly equally spaced, you may have "dead air" spots in the attic. That would nto be good.

    In Florida I prefer fully vented metal soffit. Lots of airflow. The humidity here is brutal and air has to readily flow at all times. In my house the gable vents are about twice the required area and the soffit vents are full length of the soffits.

    I hope that this helps. I would check your codes locally and figure out the areas, and assure they are correct. Remember that if the soffit vent is blocked to the cardboard openings that air will not flow there anyway. That would be unusual but I have seen it before.


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