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  1. #1

    Cons of running duct up exterior wall?

    Just about the pull the trigger on my heatpump install. With the plan of my two story it makes it almost impossible to run ducts to the second story in an interior wall. What are the cons of running duct work up the exterior wall? I assume I lose the insulation value in that wall and the duct will have to be insulated itself. Anything else?

  2. #2
    Join Date
    Feb 2007
    Location
    Northern Ontario
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    128
    you cant run in a closet weve done that many times

  3. #3
    Join Date
    Dec 2003
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    107
    Quote Originally Posted by kvanbrandt View Post
    Just about the pull the trigger on my heatpump install. With the plan of my two story it makes it almost impossible to run ducts to the second story in an interior wall. What are the cons of running duct work up the exterior wall? I assume I lose the insulation value in that wall and the duct will have to be insulated itself. Anything else?
    I'm a homeowner but I wouldn't think it wouldn't be a whole lot different that having ducts in the attic, except on the outside the duct would be subject to water intrusion that you don't have in the attic.

    I would be concerned about the appearance factor. Running ducts on the exterior would be uglier than an ol' mud rail fence. Seems it would be a negative factor if you ever plan to sell your house IMO.

  4. #4
    Join Date
    Dec 2007
    Location
    Cedar Grove, Wi-Sheboygan
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    1,582
    I just did this very samething to my home this past summer, as I wasn't about to rip open my interior walls I was in the process of residing my home so I had the luxury to put them in from the exterior of my house which was kinda of nice. I opened the wall cavity where they needed to go and then prior to when I set the duct work in place I sealed the duct work set in place and then used spray foam around the duct work and then re-sheeted the cavity using 1/2" insulation bd and then 1/2" insulation bd over the entire house and re-sided the house. Everything worked out fine. Oh I also put house wrap all around the exterior tapping all joints on the wrap plus the foam bd insulation and it has made a huge difference in heating the house.

  5. #5
    Join Date
    Mar 2005
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    burlington county n.j.
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    9,642
    Quote Originally Posted by mcginkleschmidt View Post
    I'm a homeowner but I wouldn't think it wouldn't be a whole lot different that having ducts in the attic, except on the outside the duct would be subject to water intrusion that you don't have in the attic.

    I would be concerned about the appearance factor. Running ducts on the exterior would be uglier than an ol' mud rail fence. Seems it would be a negative factor if you ever plan to sell your house IMO.



    pretty sure he meant running them INSIDE the exterior wall.............


    not the preffered placement but it is done all the time.

    can't run up interior wall then thru the floor joist space?

  6. #6
    Join Date
    Dec 2007
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    Cedar Grove, Wi-Sheboygan
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    Quote Originally Posted by kvanbrandt View Post
    Just about the pull the trigger on my heatpump install. With the plan of my two story it makes it almost impossible to run ducts to the second story in an interior wall. What are the cons of running duct work up the exterior wall? I assume I lose the insulation value in that wall and the duct will have to be insulated itself. Anything else?
    I believe he asked for pros and cons of either but I thought I would give my opinion on my situation as it worked for me although I am not sure the OP wants to do all the work I did although as I mentioned I was already half way there so it was a no brainer for me But if he has vinly siding it can be done fairly easy just alot of work.

  7. #7
    Join Date
    Feb 2007
    Posts
    533
    Cons in my opinion

    1) Security (easy to gain entrance into your home)

    2) Ugly (It should decrease your property value and piss off your neighbors)

    3) If done properly with insulation and waterproofing and make it look like it is part of the
    House it will be quit Costly

    I recommend you contact a local contractor and let them help you find the right solution
    to your problem.











    0

  8. #8
    Join Date
    Dec 2007
    Location
    Cedar Grove, Wi-Sheboygan
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    Hmmmmm, I was thinking more inline of opening the wall cavity from the outside of the house and placing the ductwork inside the walls from the exterior of the home.... this is in no way unattractive to the ey or neighbors as it is inside the wall and covered by the siding on the exterior of the home. As I mentioned it is alot of work but if in my opinion it's alot less work then ripping open interior walls and re-drywalling and or painting or wallpapering, removing base bd molding. Much easier to do from the exterior of the home if the OP has no other options. But if nothing else OP could build a chase way in the corner of a room from the main floor and chase it up to attic or closet in a second floor bedroom and then run duct work in that fashion would not be all that bad to deal with or do as this is definately the lesser of 2 evils as opposed to doing it from the exterior of the home. And depending on the size and location of rooms or layout required for the duct runs the OP may need to build more than one chase way to supply the second floor. Many years ago this was done for plumbing in 2 sotry homes or duplex homes where the expansion of a 2nd bathroom was needed and the easiest route was just go straight up fromthe basement to second floor and either box it in or they would sometimes leave it out in the open.

  9. #9
    Sorry for not being clear! The ducting would be run inside the exterior walls, so you wouldn't be able to tell they were there unless you knew. There aren't any open web trusses in the house and only 8ft ceilings, so a bulkhead is out of the question as is drilling through the trusses. My assumption, which I should be able to clear up today, is that they run from the basement up the exterior wall to the attic and drop the vents down that way. I think my main worry is the amount of insulation I'd be losing in that exterior wall.

  10. #10
    Join Date
    Oct 2008
    Posts
    483
    I think I am decently qualified to throw my opinion on this one.

    First off, I am not 100% clear on what you're proposing or visualizing. Your "exterior wall" is the same as your interior wall. Being, there is only one wall. You probably have a stud wall, with OSB board and vinyl or brick on the outside, and sheetrock on the inside. There is a 3.5 inch cavity between that wall and you can't run any sort of main duct in that. You can barely run a single room supply or return there and I don't like their nc levels when I've seen it done that way even.

    Again, I've not seen your floor plan or house. If you want to send me a copy of your floor plans I'll be glad to give my advice on where and what you can do.

    I'm a consulting mechanical engineer and work in HVAC system design. I do this all the time and we get some things through some crazy places.

    Each return and supply will be on the order of 16" square give or take PLUS insulation which should be 2" ALL the way around. So add 4". Of course you can make them rectangular a little or split them etc if you're trying to get fancy but, roughly, thats what you're looking at.

    Is this a packaged unit sitting on the ground outside or is this a split type with the air handler down in the basement and the unit with the big fan on top sitting outside on the ground?

    Someone before suggested using a corner of the interior somewhere and building a chase there to route them in. That would certainly work.

    Another option I'd suggest is to try and use some closet space if possible. Often floor plans stack closet placement anyway, so you could take half of two closets, one on each floor and go up that way. Though you sacrifice storage space.

    Another choice would be to run up the outside of the house in such a fashion that the ductwork would actually be sticking off the outside wall. IF you were gonna go that route, I'd suggest building around it with wood framing and cover it in either matching vinyl or brick or whatever your house exterior is.

    If you did NOT build a boxing around it as stated above you'll have problems. We overy so often have to do a small commercial install like this and its VERY difficult to get a contractor who knows how to build this to where it looks decent, water doesn't pool on it, all the joints are sealed well, etc etc. Plus it will never look very good.

    If you build around it, it'll look a lot like a chimney sticking on the side of the house, it just wont go on up above the roof. it wont look too bad and really shouldn't be all that difficult and I'd think easier and cheaper than ripping out interior walls.

    I hope thats of help. Let me know if you'd like any clarification of what I'm suggesting and if I'm not understanding your request correctly please let me know.

  11. #11
    Join Date
    Dec 2007
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    Cedar Grove, Wi-Sheboygan
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    If you have the work done like I did my duct work with putting either 1/2" or 3/4" rigid foam bd insulation to close up the wall cavity beased on the thickness of the outside sheating of course and use spray foam to fill the gaps between the duck work and wall studs the full lenght of duct run I would think you will be ok. My home is in Wis, and has been in for nearly 2 heating seasons and all is fine not much for heat loss in that wall cavity that I have noticed nor is or has been any frost build up inside the home on the oposite side of where the duct work is installed. So I would think as long as the work is done using the right material when the opening is closed up you should be ok, especially if your in a warmer climate then I am.

  12. #12
    Join Date
    Oct 2008
    Posts
    483
    To dan or OP:

    Maybe you have a better understanding of what the OP is trying to do. To me, as I mentioned, the wall is very thin.

    I dont know how to suggest the OP seal the wall back, when I don't see how you can fit anything in that wall.

    You could run off the exterior, to give you tate xtra 3.5" and have the ducts stick off the outside maybe 15" rather than 19 or 20, but the cost to me wouldn't be worth tearing it up, I'd just add the exterior chase as I mentioned.

    With that said, I wouldn't worry too much about losing that small amount of insulation at the exterior. I like Dans idea of using spray foam to seal around the edges of the duct just to keep infiltrating fast blowing air from getting trhough the gaps, but this small area as a whole isn't gonna compromise your total envelope very much cause the ducts themsevles are insulated and that'll keep that cold air off of the house.

  13. #13
    Quote Originally Posted by Rhizzlebop View Post
    I think I am decently qualified to throw my opinion on this one.

    Again, I've not seen your floor plan or house. If you want to send me a copy of your floor plans I'll be glad to give my advice on where and what you can do.

    I hope thats of help. Let me know if you'd like any clarification of what I'm suggesting and if I'm not understanding your request correctly please let me know.
    I guess going up the interior walls are out of the question because they would have to cut through the joists to make their runs, while going up an exterior wall into the attic is what they're thinking.

    Can't figure out how to PM you, but if you want to shoot an email off to k.vanbrandt@gmail.com I'll forward you my plans. I appreciate it!

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