Insulating from the outside

Discussion in 'Insulation and Radiant Barriers' started by monzamadman, Jun 10, 2013.

  1. Jun 10, 2013 #1

    monzamadman

    monzamadman

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    Hi everybody, I am wondering what,how I should go about this. I will be tearing off the old siding,and the boards under it and replacing it, I want to insulate the walls while I have everything off. What type of insulation should I use? What about vapor barrier?
     
  2. Jun 10, 2013 #2

    nealtw

    nealtw

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    WElcome the site. Depending on where you live, some zones want the vapour barrier on the inside some on the outside and some don't use any. I hope you planning on doing this a piece at a time the sheeting is structual.
     
  3. Jun 11, 2013 #3

    monzamadman

    monzamadman

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    We live in minnesota,i am planning on doing a section at a time.As for insulation should i use faced or unfaced?If it is supposed to be on the inside shouldn't it be between the sheetrock and the studs?
     
  4. Jun 11, 2013 #4

    WindowsonWashington

    WindowsonWashington

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    In theory, your vapor retarder levels should be to the warm side.

    In your application, you would want it to be unfaced in a perfect application but if you get enough R-Value to the exterior, it is less imperative.

    What is the wall construction?

    Plan on spending some money on spray foam and getting it done right. If you take your time, you can detail and build a really fantastic wall system.

    Vapor Retarder Levels

    http://www.buildingscience.com/documents/reports/rr-1012-residential-exterior-wall-superinsulation-retrofit/view?searchterm=exterior%20foam
     
  5. Jun 11, 2013 #5

    nealtw

    nealtw

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    There are a few ways to go, doing it wrong is as bad as not doing it. The idea is to stop air flow from inside from getting into the wall. Paper faced would go against the interior but there is no way to seal all the gaps. So if that's what you use you would have to seal all swtch and outlet boxes to stop airflow and then paint inside with a retarder paint. I would use poly 6 mill and wrap the stud and tuck it into the gavities. tape the joints and seal it to top and bottom plate with acoustic sealer and use batts. In a wet zone some gaps want to be left in the sheeting so moisture can escape to the outside, every bay.
     
  6. Jun 11, 2013 #6

    monzamadman

    monzamadman

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    As far as I can tell the walls a regular 2x4 framed walls,I was told it could be balloon construction, don't know if that would make a difference. Unfortunately I have to do this myself to keep costs down,but it still needs to be right so I don't have any issues later. What I need is the best way to do it this way,as the siding and the boards under need replacing. This is why I am doing it this way.
     
    Last edited: Jun 11, 2013
  7. Jun 11, 2013 #7

    WindowsonWashington

    WindowsonWashington

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    Balloon framing does make for some more leakage but if you are stripping the walls on the exterior, you can cut and install blockers between the floors. This should be done from a fire standpoint anyway.

    Get some putty pads to go around all the outlets and penetrations in the walls.

    Check with code or engineer as to what the requirement is for either let in bracing or plywood sheathing.
     
  8. Jun 11, 2013 #8

    monzamadman

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    Thanks for the info, I will check what code is,and figure out if it is balloon framed.
     
  9. Jun 12, 2013 #9

    bud16415

    bud16415

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    With your location and talking about balloon framing and the type of siding and sheathing you have it sounds like you have a century old structure. I have seen them with sheathing on the outside then siding and lath and plaster on the inside. I have also seen them with the sheathing on the inside then the lath and just clapboard siding on the outside. The third method is what I have found in the house I’m renovating now and that is sheathing on both the inside and outside (1” rough saw) lath and plaster on the inside and clapboards on the outside. In my case there is also hard siding circa 1950 over that and then foam and vinyl siding over that circa 2000.

    My concern in your situation is all that material really gone bad and needing replaced. You are really talking about a big job and chances are the original sheathing is still solid. In my case the sheathing is hemlock by the looks of it and it has darkened over the 100 plus years it’s been up there but is still 100% tough as nails. Without photos and until you open it up you won’t know for sure and is only a guess on my part. Quite often the lower one or two boards around overgrown landscaping might have rot and the south side the sun takes a toll on the clapboards. As Neal mentioned in these old places that sheathing was somewhat structural and many times run on the diagonal. They had it on there when they put the windows in and stuff is nailed to everything. Prying all that off may also cause problems with the interior walls if lath and plaster as you will be twisting the studs around getting the sheathing off.

    I’m no insulating expert but I wouldn’t rule out just removing the old siding replacing any bad sheathing and boring holes and adding blown in insulation from the outside and then whatever the pros would recommend as wrap and foam then new siding.

    Just a thought and you may have already figured out you need it all gone.
     
  10. Jun 12, 2013 #10

    WindowsonWashington

    WindowsonWashington

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    Being able to get to the backside of the interior wall (plaster and lath or drywall) is a great benefit but will require the additional expense of pulling the sheathing.

    If you are going for high performance envelope, that is what you are going to have to do.

    Dense packing the walls, while not requiring the tear down of the sheathing, is going to be near impossible if you don't know what is in the walls or if it is balloon framed.
     
  11. Jun 12, 2013 #11

    bud16415

    bud16415

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    It’s been my experience once you get the clapboards off it’s not too hard to figure out what’s behind the sheathing. You will see the nailing and if the sheathing is rough sawn as most of these old houses are there are gaps and such to poke around with a wire to find fire breaks and if the house is balloon or has plates. You can always easily drill a few holes to see what you have also or to gage how well your walls have filled. I have also seen them putting foam in this way.
     
  12. Jun 12, 2013 #12

    WindowsonWashington

    WindowsonWashington

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    +1

    If they are old skip sheathing, you will see everything you need to see.

    Do not use that drip foam for closed cavities in my opinion. I have used it on a couple of jobs and the results were disastrous in a couple of cases. Much better suited for hollow blocks.

    I have yet to use AirKrete but I would love to try it.
     
  13. Jun 12, 2013 #13

    nealtw

    nealtw

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    The foam they use for closed cavities is deffernt and chemicals can get into house that does not have vabour barrier.
     
  14. Jun 12, 2013 #14

    monzamadman

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    The house was built in the 20's or 30's, i do know it has boards running at an angle behind the siding,don't remember if it was rough sawn or not. There is no vegetation over grown, it was neglected for a lot of years, some since I have lived there. The siding is rotting,not on all places, and the boards behind are also in places, I also have to replace some windows as the wood around them is rotting too. There is nothing between the siding and sheathing, what insulation is there is compacted at the bottom. So let's figure it is a balloon framed house, if I were to do small sections at a time, that should not affect the rest of the house right?
     
  15. Jun 12, 2013 #15

    nealtw

    nealtw

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    The braces on an angle let into the studs were put there to keep the house square, because the board would not keep there. Plywood or osb on newer house do that job. So you could likey work on half of a side at a time. If the studs are rough cut, any blocking you have to put in if it is balloon will have to be ripped to fit. Hang a tarp first and roll it up above the work area because you know as soon as you open the wall the wind will blow and the rain will come. The area around the windows will likely be the worst and I would start right at one of the worst windows. Depending on what you find in some cases it is easier to change whole sections of wall.
     
  16. Jun 12, 2013 #16

    monzamadman

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    Someone help me understand why this is more difficult than just removing the old and putting new on.
     
  17. Jun 12, 2013 #17

    bud16415

    bud16415

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    It’s not really any harder than doing just that. You mentioned cost so that’s a factor. You will be taking off “X” number of square feet of siding and sheathing and the sheathing will be most likely 1” thick. So you have to look at what will be going back onto get the same build or something less as to sheathing plus whatever kind of siding you will be using to make window trim come out correct. Maybe .5 plywood and .5 foam board. I just bought .5 foam board last night and it was over 10 bucks a sheet.

    Money aside it’s just ripping it all off and stuffing in some insulation and putting it back on. Neal pointed out you can do about half a side at a time without worrying about losing structure. Will you be doing soffits and fascia at the same time and or gutters as the type of trim you use up top should match the system you will be using. When its open it’s a good time to add any wiring in the walls also. You may also find some other damage in the walls when open and the perfect time to fix them is when the wall is open.

    If you are sure it has to go then I would say just go at it and keep a tarp handy if needed.

    Good luck and post some pics once you get started we would love to see the before and after.
     
  18. Jun 12, 2013 #18

    nealtw

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    It's not but what ever you expect to find when you get there will change, sometimes better and sometimes worse. No one that has done this before wants you to be really surprised when you get there. You will run into problems that are unexpected and there are people here that will offer suggestions on how to solve them. You have suggested some rot, we think "more rot" insects, mold and knob and tube wiring, all things that will have to be addressed when you get there. It may be easy and we hope it is.
     
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  19. Jun 12, 2013 #19

    monzamadman

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    I thank all you guys for your help and I was not trying to be a dink,I was getting more confused than before I asked.i will be starting maybe this wknd or next and I will let you guys know how things go. Thank you again.
     
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  20. Jun 12, 2013 #20

    monzamadman

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    I also learned of quite a few things I have never heard of before,or would have thought to look up,thanks to you guy's. I appreciate it.
     

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