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Thread: House Wrap

  1. #1

    Default House Wrap

    Is house wrap like Tyvek necessary? Had a house builder out here in the valley said he stopped using it and would not recommend anyone in this climate putting it on there house. I'm at the point with the cabin build and need to put it on if I'm going to. Thanks for the input.

  2. #2
    Member dkwarthog's Avatar
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    When are you planning on siding the house? If it will sit exposed for a long time, I would wrap it. JMO though.

    I'm curious to read what others with more experience say about it. I think it helps combat wind infiltration and wind driven rain, but I can see where it might keep condensation moisture in the walls from evaporating as quickly.

  3. #3

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    I hope to have the siding on in the next few weeks. His comments were the same on the condensation. Said it won't let everything dry out as it should. I have no experience with building until this cabin. Reason I'm asking I have never seen anyone not use it before.

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    webmaster Michael Strahan's Avatar
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    I was in Adak a while back and noticed a number of the houses literally falling apart. I'm not a builder so I can't comment on the cause, but one of the locals told me that they were built without an adequate vapor barrier. You can see from the photos that the studs and joists have literally rotted away, from the outside edge. It may be true that the inside lumber you used on your cabin won't dry as fast as it would without a barrier, but at what price? Better a slow dry than rotting studs later.



    Here's a closeup of the same wall.




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    I am a builder... Well general contractor to be exact and the simple answer is yes and I will try to expand on my answer later today. You may want to look into typar vs tyvek though

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    Member dkwarthog's Avatar
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    I've seen those exact houses Mike. Theyre generally facing the water and that side of the houses is usually in the prevailing wind and the destroyed walls seem to be in areas subject to wind funneling. I suspect the siding and sheathing was blown off exposing the insides of the walls to rain and wind.

    On the other hand, you may have a point in that it is the wind driven rain getting into the walls that starts the rotting and then the wind is able to blow the assembly apart once the fasteners are loosened..

  7. #7

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    It is sad to see, as the folks there need "Quality" housing, and this stuff missed by a long shot!

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    Member AK Ray's Avatar
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    Quote Originally Posted by dgrant09 View Post
    It is sad to see, as the folks there need "Quality" housing, and this stuff missed by a long shot!
    The Bayshore house that Mike posted worked just fine for thirty years for hundreds of Navy and civilian families. But it is not quality? Really?

    All that housing was backed by a multimillion dollar budget for maintenance. The military spent millions every year to keep our houses dry and functioning. The private sector that now owns these buildings does not have the funding to keep them from rotting. As soon as you turn off the heat it starts to rot.

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    Member dkwarthog's Avatar
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    I dont think dgrant realized that no one has lived in or maintained those homes for a long time.

    BTW, you can buy a duplex in Adak really reasonable. Seriously.... Might cost you a bit in maintenance and to access it though...I think they were in the neighborhood of $20-25K when I asked.

  10. #10
    webmaster Michael Strahan's Avatar
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    Quote Originally Posted by AK Ray View Post
    The Bayshore house that Mike posted worked just fine for thirty years for hundreds of Navy and civilian families. But it is not quality? Really?

    All that housing was backed by a multimillion dollar budget for maintenance. The military spent millions every year to keep our houses dry and functioning. The private sector that now owns these buildings does not have the funding to keep them from rotting. As soon as you turn off the heat it starts to rot.
    I'm not sure what the deal is with those particular houses, but I saw three different styles of houses out there, that were apparently built as separate projects (not counting the older duplexes on the hill above the airport). The oldest ones were the single-level duplexes, then these places in the photo I posted, and then I think the most recent ones were the two-story duplexes that many of the locals currently inhabit (some of these are rentals for visitors). The newest ones (the rentals anyway) reek of mold and dead meat. I think the dead meat smell is from hunters cleaning caribou in the garage and not cleaning up after themselves. We hung meat in the garage, but we put a tarp down first, and disposed of it when we left, along with the bones and such.

    The original duplexes look like they're in pretty good shape, but they are older. I have not been inside any of them though, so I don't know if they have that mold smell.

    I think these houses were built by different contractors, and some may have done a better job than others.

    Anyway, back to the topic at hand---

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  11. #11
    Member cdubbin's Avatar
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    I've been hearing this fable for years, that Tyvek somehow "holds" water in a structure, when in reality it is more permeable than the sheathing material it is usually fastened to (we also install Tyvek directly to studs at times, as in panel siding applications)....house wrap is essential for keeping wind-driven rain off of OSB sheathing( which will soak up water and expand, compromising it structurally) until the siding is installed. Think of it as kind of a "last-ditch" material, it keeps the framing, insulation, and sheetrock dry if water penetrates the exterior finish.

    That framing in Mike's pics does indeed look like the victim of a poor or non-existent vapor retarder; the dewpoint of a wall in northern climates is typically towards the outside.....that is, the vapor-laden air, which is always trying to flow from warm to cold (take a cold beer out of the fridge and watch the water condense on it, same principle), passes through the wall and hits the cold sheathing, condenses there, and causes rot and mold. In an air-conditioned structure in a humid environment (think the southern U.S.), the reverse is true; vapor barriers in this situation will cause rot and mold on the inside sheathing.

    Here's an informative article:
    http://www.greenbuildingadvisor.com/...stive-barriers
    " Gas boats are bad enough, autos are an invention of the devil, and airplanes are worse." ~Allen Hasselborg

  12. #12

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    Thanks for the info. I was leaning toward putting it on. A couple of hundred bucks to protect the large investment is not worth skipping if it helps.

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    During the siding of my cabin the same questions was raised. My research through local siding suppliers, discussion groups on line and product manufacturers left me with these conclusions;
    1 -tyvek does a great job of keeping out wind, permits water vapor to escape from the inside to outside (like gortex) but does allow not liquid through.
    2 -Your inside vapor barrier must be tight and great detailing done on the Tyvek to prevent any moisture from getting behind it.
    3 -Tyvek will allow liquid trapped between it and the exterior sheathing to evaporate....but very slowly. This is where the rot can get started.
    4 -15# or 30# felt will keep the wind wash from affecting your building too.
    5 -Felt will allow trapped water to evaporate more quickly than Tyvek avoiding the rot issue.

    Old time builders did use 15# felt behind most of their siding.

    My cabin has metal siding so I opted for 30# felt (per some cities code and the siding manufacturer's recommendation) with great detail on taped seams, flashing and overlapping as one would do for water run off for a roof. Time will tell how well it holds up.
    My interior vapor barrier is gooped and tapped very well at all openings and seams.

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    Here's a good article from the CCHRC: http://cchrc.org/docs/energy_focus/2...nd%20Wraps.pdf

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    Another good article on house wrap:

    http://www.finehomebuilding.com/how-...ousewraps.aspx

    A lot depends on the exposure of the house. If it is going to be hit by a lot of wind you should really pay attention to siding, wrap, and even consider rain screens. If it is in a location where it won't see much wind driven rain then it isn't as important.

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    Quote Originally Posted by Bear View Post
    I am a builder... Well general contractor to be exact and the simple answer is yes and I will try to expand on my answer later today. You may want to look into typar vs tyvek though
    I vote for Typar rather than tyvek too. It is stronger and quieter. I had it on my home for 3 years before siding it, held up fine. Now if only they would make it with lines on it to look like siding.....

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    As far as that picture of the building, were the other walls rotting out as well? An inadequate vapor barrier(retarder) would affect the other walls as well. I am leaning towards the sloping of the roof to that side of the building and the lack of eaves doing the most damage, all the water pouring down the siding will find its way in eventually.... Interesting for sure.

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    Member SANDRAT's Avatar
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    I was thinking more of using 30# felt as I'm doing the bottom 4' in river rock, wood siding above. The felt is the preferred substrate along with lath for the masonry. Should work well with the wood above also.


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