+ Reply to Thread
Results 1 to 5 of 5
  1. #1
    Join Date
    Jan 2010
    Posts
    3

    Default Balloon Framing, Stack Effect, and Moisture Problems

    Hi all, this is my first post, but I've been reading the forums for a long while. Canuck, I'm especially hoping that you'll be willing to weigh in here.

    I live in a very cold upper midwest climate. Our 82 year old house is balloon framed. I believe it has fire stops, but I'm not sure. At any rate, the stud bays do not open into the basement. But the second floor stud bays *DO* open directly into the attic.

    An energy audit has shown tremendous heat loss into the walls. And with at least the second floor walls opening into the attic, my guess is that the stack effect in our house is quite significant. (Our inability to keep the place warm without constantly keeping the furnace on suggests the same.)

    I would like to curb this stack effect, and from what I've read the places to start are insulating the rim joists in the basement and the insulation in the attic. I'm going to tackle the basement soon. My main question is about the upper part of the house.

    Currently there is very old blown fiberglass under the attic floor. Then, on top of the floor, there is a good 6 inches or so of fiberglass that was blown in August 2009 after the previous owners rewired the whole house as a condition of our offer to purchase.

    My current thinking has me leaning toward the following: remove new fiberglass; take up attic floor; remove old fiberglass; have rock wool blown into the second floor stud bays that open into the attic; cap stud bays with foam; foam other air chases into the attic; roll out either fiberglass or rock wool batts and cover with old attic flooring; roll more batting on top of floor to achieve further R-value.

    I have two questions: (1) is there anything about this game plan that invites moisture to be trapped in either the rock wool wall insulation in second floor wall or else the empty first floor walls? (2) if the answer to (1) is "No," is there another flaw with this plan that I'm not seeing? For example, will I have simply traded a basement-to-attic stack effect with a basement-to-tops-of-first-floor-walls stack effect?

    Perhaps it's obvious by now that I don't have a clue what I'm talking about. Any and all help thinking all this through will be greatly, greatly appreciated.

    Thanks again.

  2. #2
    Join Date
    Aug 2007
    Location
    The Great White North
    Posts
    4,045

    Default Re: Balloon Framing, Stack Effect, and Moisture Problems

    Quote Originally Posted by wg2 View Post
    Hi all, this is my first post, but I've been reading the forums for a long while. Canuck, I'm especially hoping that you'll be willing to weigh in here.

    I live in a very cold upper midwest climate. Our 82 year old house is balloon framed. I believe it has fire stops, but I'm not sure. At any rate, the stud bays do not open into the basement. But the second floor stud bays *DO* open directly into the attic.
    Sounds as though fire stops are installed in the basement --- likely horizontal blocks of wood between the joists. You could remove one and shine a strong light up the wall cavity to look up and see if cross blocking midway exists.
    With the openings in the attic you could use a roll of string. Tie a weight to the end and drop the weight down the wall to see how far it goes to see if cross blocking exists midway.

    The cross blocking is important to know if they exist.

    An energy audit has shown tremendous heat loss into the walls. And with at least the second floor walls opening into the attic, my guess is that the stack effect in our house is quite significant. (Our inability to keep the place warm without constantly keeping the furnace on suggests the same.)

    there are 2 main things that seem to be an issue for heat loss. I'm surprised the auditor wouldn't have explained what's happening there. Without insulation there is nothing resisting heat transferring through the walls. Also since the wall cavity is open to the attic you have significant air movement to and from the attic ---- carrying warm air up into the attic and cold air dropping from the attic. I would also suspect condensation issues in the attic because of this.

    I would like to curb this stack effect, and from what I've read the places to start are insulating the rim joists in the basement and the insulation in the attic. I'm going to tackle the basement soon. My main question is about the upper part of the house.
    Stack effect really deals with air movement. Insualating the rim joist area will resolve heat loss and cold infiltration at the point of the floor joists meeting the foundation.

    You might believe that filling the wall cavity with an insulating material should stop the stack effect. However, if there is a source of air infiltration you will still have stack effect that will occur through the insulation which reduces the performance.

    You need to stop air circulating to curb the stack effect. By air sealing the bottom and tops of the wall cavities this would greatly reduce the stack effect and improving the performance of the insulation.


    Currently there is very old blown fiberglass under the attic floor. Then, on top of the floor, there is a good 6 inches or so of fiberglass that was blown in August 2009 after the previous owners rewired the whole house as a condition of our offer to purchase.

    My current thinking has me leaning toward the following: remove new fiberglass; take up attic floor; remove old fiberglass; have rock wool blown into the second floor stud bays that open into the attic; cap stud bays with foam; foam other air chases into the attic; roll out either fiberglass or rock wool batts and cover with old attic flooring; roll more batting on top of floor to achieve further R-value.

    This is where it's important to know if cross blocking exists midway in the wall cavites.

    You could push the existing loss fill down the wall cavity and insert more loose to fill the cavities. If there isn't cross blocking you may be able to fill the entire wall cavity from the first floor to the top of the second ----- or at least the entire 2 floor wall cavities.

    If there is cross blocking you will have to do 2 inserts ----- one from below the cross block and one from the top.

    As for the attic ---- if you are not using the space for storage --- do you need the floor? Otherwise remove the floor -- install whichever insulating material to the desired amount ensuring to cover the joists.

    I have two questions: (1) is there anything about this game plan that invites moisture to be trapped in either the rock wool wall insulation in second floor wall or else the empty first floor walls? (2) if the answer to (1) is "No," is there another flaw with this plan that I'm not seeing? For example, will I have simply traded a basement-to-attic stack effect with a basement-to-tops-of-first-floor-walls stack effect?

    Perhaps it's obvious by now that I don't have a clue what I'm talking about. Any and all help thinking all this through will be greatly, greatly appreciated.

    Thanks again.
    The only concerns with trapping moisture would be allowing warm humid air into a cold zone allowing it to condense. By installing insulation in the wall cavities and air tight sealing the tops in the attic should go a long way of preventing any issues

    Chances are if balloon framed homes are normally found in your area then insulation contractors are likely well experienced on how to handle these concerns..

    Hopefully this makes sense and helps.
    "" an ounce of perception -- a pound of obscure "
    - Rush

  3. #3
    Join Date
    Mar 2009
    Posts
    1,387

    Default Re: Balloon Framing, Stack Effect, and Moisture Problems

    Howdy, i too have a balloon framed grand home. First leave the attic insulation alone. but consider snaking the wall to see if any insulation in it. You can use a 10' piece of 1/2 pex pipe run it into the cavity from the attic if no resistance likely no insulation an consider looking down with a flashlight. If none i would have cellulose insulation blown in from the attic the cellulose does not allow air to move threw it but does all ow moisture so it will not be trapped. Then look for dirty insulation in the attic as this tells of air movement. consider using spray cans of foam insulation to seal around any openings into the attic around pipes etc. Fiberglass does not stop air movement so thats why to seal any openings into the attic threw the fiberglass....

  4. #4
    Join Date
    Feb 2011
    Posts
    2

    Default Re: Balloon Framing, Stack Effect, and Moisture Problems

    I live in a house built in the early 1900's and have balloon framing that is open to the crawl space and to the attic. I would like to insulate the attic and the first floor floors, I do not have money for filling all the walls. In reading this post I have a question about the statement, and my situation.

    "Also since the wall cavity is open to the attic you have significant air movement to and from the attic ---- carrying warm air up into the attic and cold air dropping from the attic. I would also suspect condensation issues in the attic because of this."

    What would happens in the wall if they are capped in the attic with out insulating the walls?

    What happens if these walls are not capped and insulation is blown into the attic?

    Thanks,

  5. #5
    Join Date
    Mar 2009
    Posts
    1,387

    Default Re: Balloon Framing, Stack Effect, and Moisture Problems

    Howdy i would install fire blocking ( 2by10") to stop the potential of fire from the basement to run up the walls first. if not wood then install rock wool in theses openings as it has a good fire retarding rating. Then i would have insulation blown into the wall cavities keep in mind if you have knob and tub wiring in the walls you cannot insulate them until that wiring is replaced as it needs air to keep it from overheating and causing fires.... At the top of the wall a layer of rock wool as it does not allow air movement. fiberglass does and you want to retard chimney effect of the walls. Condensation in a non insulated wall is allowed to travel out threw the wall an in threw the interior wall finishes so capping the wall should not effect the walls ability to dry. plus when you are able to afford wall insulation the blown in can be installed by simply removing the rock wool and then re setting it when done. Check an see if in your area there is governmental assistance in weatherizing your home. Some government monies have been available based on income.
    Last edited by Timothy Miller; 02-02-2011 at 10:52 AM. Reason: typo

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •