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  1. #1
    Join Date
    Nov 2008
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    Monkton, Vermont
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    2

    Default Camp insulation question

    Greetings all!
    New here but been reading JLC since it was New England Builder!
    We have been asked to do some renovations to a camp in Vermont on Lake Champlain. Among the work is insulating the exterior walls and installing beaded pine on the interior surfaces. The construction is rough sawn 2x4s with drop siding directly over the studs, no felt paper. There is water staining visible on the interior where presumably wind driven rain has forced its way in past the siding. I am, very leary of just installing fiberglass and a poly vapor barrier.
    My thought is to cut a piece of felt paper for each stud cavity and staple it to the back of the siding. Then to spray a bead of foam around the perimeter of each cavity. Then the fiberglass and poly vapor barrier.
    This seems fairly tedious but I am concerned about having a serious mold or rot problem down the road.
    I have also considered having the cavitys foamed but I am not sure the budget would handle it.
    I appreciate your insights on this.
    Tim

  2. #2
    Join Date
    Feb 2007
    Location
    Portland Maine
    Posts
    434

    Default Re: Camp insulation question

    Will the camp be used year round?

    Is it heated in the winter, and what is the heating system?


    Is it cooled in the summer?


    All of these questions are important to a properly performing wall assembly. My understanding is air sealing is the most important aspect of moisture control and insulating, not sure how felt paper foamed to the studs will perfrom in that respect. A poly vapor barrier is generally considered a bad idea in the building science community these days- but your specific wall assembly and building heating/cooling specifications are extremely relevant to that decision.
    Mike


    The Democrats are the party that says government will make you smarter, taller, richer, and remove the crabgrass on your lawn. Republicans are the party that says government doesn't work, and then they get elected and prove it. -P.J. O'Rourke

  3. #3
    Join Date
    Feb 2008
    Location
    North Central Vermont
    Posts
    1,866

    Default Re: Camp insulation question

    Quote Originally Posted by Powerwagontim View Post
    been reading JLC since it was New England Builder!
    Me, too. Also a charter subscriber to FHB.

    We have been asked to do some renovations to a camp in Vermont on Lake Champlain.
    Hmmm... high wind and moisture area!

    Among the work is insulating the exterior walls and installing beaded pine on the interior surfaces. The construction is rough sawn 2x4s with drop siding directly over the studs, no felt paper. There is water staining visible on the interior where presumably wind driven rain has forced its way in past the siding.
    Yup, without a weather-resistant barrier (WRB), you're going to get that wind-driven moisture through the siding.

    I am, very leary of just installing fiberglass and a poly vapor barrier.
    I would also be leary of using either, as fiberglass is as close to worthless as insulation can be and a poly vapor often creates more problems than it solves.

    My thought is to cut a piece of felt paper for each stud cavity and staple it to the back of the siding. Then to spray a bead of foam around the perimeter of each cavity. Then the fiberglass and poly vapor barrier.
    This seems fairly tedious but I am concerned about having a serious mold or rot problem down the road.
    This would at least eliminate wind-driven moisture in the insulation bays, but not at the outer edge of each stud which may end up saturated and unable to dry.

    I have also considered having the cavitys foamed but I am not sure the budget would handle it.
    This would certainly increase the R-value of the wall assemblies and make them airtight (as long as the foam is installed properly and no wood shrinkage occurs), but would also concentrate the moisture-storage in the wood studs and possibly allow saturation and consequent mold or rot.

    You're not going to like this suggestion, but I would remove the siding and install a WRB (15# felt works better than plastic housewraps), back-prime the siding before re-installation and seal the end-grain, insulate with dense-pack cellulose (has high moisture storage capacity), use the air-tight drywall system for indoor air-sealing and then apply the beaded pine over that.

    But, if this is to be used merely as a camp, that might be overkill. If it's to be used as a year-round residence, then it would be worth doing it right.

    - Robert

  4. #4
    Join Date
    Jul 2004
    Location
    NOLA
    Posts
    4,018

    Default Re: Camp insulation question

    You can try this.
    It is a inset rainscreen.
    In the detail I show 1" XPS spaced from the siding min 3/8".
    Use 3/8" foam or plastic corrugated sign board.
    Seal all of the leaks and it should do the job.
    Foam inside the 1" XPS is optional.

    Bill R
    Attached Files Attached Files

  5. #5
    Join Date
    Feb 2008
    Location
    North Central Vermont
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    Default Re: Camp insulation question

    Quote Originally Posted by Bill Robinson View Post
    You can try this.
    How 'bout attaching the sketch in a universal graphic format, like jpeg, so those of us who don't mess with SketchUp can see it?

    But there are several problems with what you're suggesting, which isn't a rainscreen. There are two types of rainscreen: simple (also called a drainscreen) and pressure-equalized. A simple drainscreen is an air gap behind, for instance, brick cladding with weep holes to allow any water penetration to escape, either by gravity or by capillary action back through the brick.

    A true - or pressure-equalized - rainscreen, requires vertical furring and a fully-vented air cavity behind the exterior cladding which:
    - equalizes air pressure on both sides to prevent pressure-driven water penetration
    - allows considerable convection to evaporate any water that does penetrate
    - decouples the cladding from the (weatherproof) sheathing to prevent capillary migration of water into the building envelope

    What you propose does none of the above. It creates a dead air space to collect moisture and trap it, without the possibility of either gravity drainage or convection to dry it out.

    A thermal envelope needs to do three, sometimes contradictory, things:
    1. prevent most water from getting in
    2. store the moisture that does
    3. allow drying of the moisture that does (and will) get in

    In the heating season, the envelope mostly dries to the outside. In the summer, to the inside. Driving rain, soaked siding, and direct sun will drive moisture inward with a stronger gradient than the winter outward moisture drive. Drying to the outside, especially if the siding is not back-sealed and has a high surface film finish (like oil paint) will cause blistering of the paint.

    To handle the inevitable moisture migration, a building envelope needs to be able to breathe in both directions and contain materials with a high moisture-storage capacity. Foam has no moisture-storage capacity, so any water that does find its way into the envelope will saturate the wood framing. Cellulose has both a high moisture storage capacity and a high hygroscopicity (propensity to absorb and disperse moisture), hence it will actually protect the wood from reaching saturation.

    Aside from the environmental considerations (which are not irrelevant), plastic foams are a bad choice for several other reasons, not least being moisture management.

    - Robert
    Last edited by Riversong; 11-26-2008 at 06:24 PM. Reason: to elaborate

  6. #6
    Join Date
    Jul 2004
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    NOLA
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    Default Re: Camp insulation question

    Oh, I see.
    Thanks for the enlightenment

    Bill R

  7. #7
    Join Date
    Dec 2006
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    Upstream
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    Default Re: Camp insulation question

    "...and in this corner, weighing in at..."
    Richie Poor

    See no evil, hear no evil, speak no evil, value engineer your unit prices.

  8. #8
    Join Date
    Jul 2004
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    NOLA
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    Default Re: Camp insulation question

    Quote Originally Posted by Overbuilders View Post
    "...and in this corner, weighing in at..."
    Let me at 'im.
    MBR

  9. #9
    Join Date
    Dec 2006
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    Upstream
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    Default Re: Camp insulation question

    Uh oh...he's added the dreaded 'M'...
    Richie Poor

    See no evil, hear no evil, speak no evil, value engineer your unit prices.

  10. #10
    Join Date
    Feb 2008
    Location
    North Central Vermont
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    Default Re: Camp insulation question

    Quote Originally Posted by Bill Robinson View Post
    Oh, I see.
    Thanks for the enlightenment

    Bill R
    As someone who does training and consultation on water intrusion problems, I would have thought you'd have more to say than this.

    How about responding to what I posted?

    - Robert

  11. #11
    Join Date
    Jul 2006
    Location
    Portland, OR
    Posts
    2,397

    Default Re: Camp insulation question

    If it is to remain a camp, and the building(s) in question are sleeping buildings, either reskin them and add the WRB, or skip insulation altogether.

    They will see rain and cold when unoccupied (most of the time) and heat only occasionally. So its a people-comfort thing, not an energy thing.

    Add a housewrap air-barrier on the inside of the framing, install your pine finish, and use better sleeping bags.

    Insulating and finishing a leaky building can easily cause it to rot.

  12. #12
    Join Date
    Jul 2004
    Location
    NOLA
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    Default Re: Camp insulation question

    Quote Originally Posted by Riversong View Post
    As someone who does training and consultation on water intrusion problems, I would have thought you'd have more to say than this.

    How about responding to what I posted?

    - Robert
    What's to say Robert?
    You seem to have made up your mind. It is not likely I can convince you so why waste the time?
    The detail works and is being used in several climates, you are missing an opportunity to learn.
    Bill R

  13. #13
    Join Date
    Feb 2008
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    North Central Vermont
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    Default Re: Camp insulation question

    Quote Originally Posted by Bill Robinson View Post
    What's to say Robert?
    You seem to have made up your mind. It is not likely I can convince you so why waste the time?
    This is a discussion forum for building professionals. As a moderator, I would think you would want to maintain a constructive give and take. But simply offering a "solution" without explaining why it would work certainly isn't going to either educate or convince anyone.

    I offered a detailed building science-based explanation about the problems in your suggestion. If you believe my points are mistaken, then offer a rebuttal.

    The detail works and is being used in several climates, you are missing an opportunity to learn.
    I'm always open to learning. Explain why your system will work, rather than simply asserting that it does. Perhaps it's you who are missing the opportunity to learn?

  14. #14
    Join Date
    Jul 2004
    Location
    NOLA
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    Default Re: Camp insulation question

    In looking at your other posts it is obvious you have a confrontational style.

    My guess is anything I offer will only encourage your behavior.

    However, it works because the wall will be allowed to work much the same way it has, with a gap behind the siding to drain moisture, much like the gapm behind brick or in a typical rainscreen, and yet stop or slow, air and heat migration.

    Now you are free to tell me why that doesn't work.

    I noticed in another thread you challenged someone when they recommended installing ducts the correct way. Did you really expect an answer?
    Or were you looking for something else to challenge?

    You could tell me why it won't work. It might help your position if you looked at the detail.
    Bill R

  15. #15
    Join Date
    Jan 2005
    Location
    Southern Maryland
    Posts
    338

    Default Re: Camp insulation question

    sounds like the buildings were constructed like appalachian trail shelters. Why are they worried about a little rain?

    Not sure what "drop siding" is but if I were taking this job I would inform the client about the water intrusion. Insulating those walls is a bad idea.

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