Let's talk building wrap...

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  #1  
Old 10-27-13, 08:16 PM
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Let's talk building wrap...

OK, I know there's been a lot of discussion out there about Typar vs Tyvek and which is better. I'd certainly like input on this as I myself have heard convincing arguments for either depending on what criteria is used. (water resistance, breathe-ability, ease of install...

I will however throw one additional product in the mix to confuse this matter further.

I was recently hunting around for deals as I do when planning a build, and came across this product at Lowes (Canada) called Pactiv

Pactiv 150-ft x 9-ft House Wrap

At $99 for a 9' x 150' roll it's more than 50% cheaper than Typar or Tyvek

Question is, will it be adequate for the job?

Let me put this in context for the purpose of this discussion

I'm about to build a stick-frame shed that absolutely has to get done before it gets really cold or I wont be able to empty my garage to work on my motorcycle over the winter. (not an option)

The issue it that this building may have to go the entire winter without siding....Thus I need to leave building wrap on it.

Next year, I'll be re-siding the second story of my house and doing it myself, there will be longer periods with only the building wrap as protection before I can get the siding on.

I'm all about spending a few more bucks to protect my investment...But is Typar or Tyvek just that, or just a waste of money when I could buy this Lowes product?

I've only ever used Typar but I'm open to options. I have no experience with anything else with which to compare it. Certainly I would take fewer risks with my house than I would my shed...But don't want the shed to rot out either.

Home Hardware has a product called "Housewrap" but priced the same as the Typar and Tyvek I figured I'd leave it out of this discussion
 
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Old 10-27-13, 10:42 PM
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Hi Joe,
I have not done the research, but experience with both ty products says don't leave them exposed for long periods of time. Any area that flexes with the wind will become useless as a rain barrier. I see it done all the time and I learned my lesson doing the same.

If the product will deteriorate to "useless" over the winter, I would look for a less expensive temporary solution.

Let's see what the pros have to say, after they have their morning coffee.

Bud
 
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Old 10-28-13, 04:31 AM
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How many linear feet will be required for your shed. You can always install the WRB using cap nals and lattice strips, depending on its condition when you decide on siding it, you can leave it, or remove the WRB and install fresh. 150' will go a long way.
 
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Old 10-28-13, 05:42 AM
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While it's true that WRB's degrade in sunlight, the main thing is keeping water from getting under the top edge. As long as that doesn't happen, and you use enough fasteners to keep it from blowing off in a high wind, you will be fine no matter what type you choose.
 
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Old 10-28-13, 08:37 AM
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House Wrap

I know house wrap is essential, but I wonder how effective it really is since the next thing that happens after it is installed is it gets penetrated with a whole bunch of nail holes.
 
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Old 10-28-13, 08:57 AM
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I'm dealing with an 8'x12' shed here

The walls are 8' so wrapping the rest over the top there will be no top edge

I normally tuck tape over staples so I don't leave any holes

Interesting the shape this discussion had taken. A lot about how to use the wrap or weather its ok to leave it. Nobody has mentioned a real preference for one type over another.

Does this mean that everyone here feels that no one brand would perform better than the other?
 
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Old 10-28-13, 04:00 PM
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Tyvek.......................................
 
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Old 10-28-13, 04:44 PM
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Cool. What do you like about Tyvek over the others?
 
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Old 10-28-13, 05:34 PM
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I would suggest you use Tyvek too, unless you are going to be putting cedar siding on it. Tyvek's tapes stick to it well, as do other flashing tapes.

But don't over think it. This isn't rocket science. Woven housewraps like Pactiv suck. I wouldn't cover a pile of lumber with it.
 
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Old 10-28-13, 06:02 PM
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That's some good input. What's so bad about the Pactiv? Thin? Porous?

I'm thinking Its going to be best to steer clear of Pactiv given everyone's impression of it.
 
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Old 10-28-13, 06:25 PM
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Pactiv is cross-woven plastic, kind of like basket weave. Hard to cut and stringy. Greenguard, Amowrap and others are similar. Staplers snag and slightly tear at it. Have no confidence that it's waterproof under pressure.

Testing seems to agree.

See also: UMass Amherst: Building and Construction Technology » Leaky Housewraps
 
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Old 10-28-13, 07:20 PM
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Thanks!

I'd say it's worth the extra $50 for the peace of mind.
 
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Old 10-31-13, 05:56 PM
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Ok, so I thought I would add some pictures that confirm my opinion of woven housewraps. At work today I removed some siding to install some windows and found the windows were installed on top of a woven housewrap. The house has (had) vinyl siding (which allows water to normally get on top of the housewrap at the bottom corners of the windows). So you can see what a few years of this will do to a woven housewrap.



And across the top of the window, what looks like mosquito netting is really what's left of the crummy woven housewrap.

 
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Old 11-01-13, 09:13 AM
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This is great!

XSleeper - I read your links to the studies and tests however, there's nothing like a real-world example like this to really illustrate the point. Your picture has definitely told a thousand words.

You really seem to have some experience in this area so I'd really like your opinion on a couple of things:

1) Where you say, "The house has (had) vinyl siding (which allows water to normally get on top of the housewrap at the bottom corners of the windows)"

I've only ever done a little siding, but I do plan to use standard vinyl on my shed. It will have windows and doors. I was not aware that there were ANY areas where it is normal for water to come into contact with the wall. I'm just wondering from where this occurs and is there is a way to prevent it?

I don't understand how, if I'm using a proper channel molding and install everything correctly, how water gets in and does what you've pictured here?

2) If I'm understanding what I'm reading in the studies - water resistance is the biggest single concern, then why use a Tyvek (or any building wrap) versus say a really heavy polyethylene sheeting? Something which we know is completely water resistant. I know it could be a bit tougher to install initially, but if you taped over staples would this not be the ultimate in water protection?

I fear the answer to this one is going to make me appear foolish, but I need to ask. Is it a vapor thing?

Thanks again.
 
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Old 11-01-13, 02:20 PM
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I don't have a lot of time to explain right now, but I know I've written several posts on this topic in the past. Maybe you can google search and find a few of them.

In short, water follows vertical j-channels down and water leaks behind the siding at the bottom corners of windows. The way to help direct that water back out is to cut a corner out of a piece of wide metal flashing (out of, say a 12" x 12" square) and install that at the bottom corners of the windows, then put the j-channel on top of that. The siding is tucked under this flashing as it is being installed, and the bottom edge of the metal flashing is cut to length at the bottom edge of the interlock. This directs that water back out to the weep holes as soon as possible.

Poly is a vapor barrier, and doesn't usually belong on the outside of the building. Tyvek and others are vapor permeable.
 
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Old 11-01-13, 07:09 PM
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Vinyl siding is designed to leak and should be installed accordingly with window skirts, flashing and a bit of caulk in just the right places to deal with the water that will leak in. Certainteed has a very nice install manual for vinyl siding.
As for house wrap, I have removed siding to find wet house wrap and rotted wood. It is not a cure all product for leaks. I don't think I would even install it when building a shed.
There are ZIP SYSTEM boards that are wood and when installed with ZIP tape allows a home to be built without the use of house wrap. It can also be left exposed for 180 days.
 
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Old 11-01-13, 07:59 PM
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I use the zip system on one home addition. It scares the dickens out of me.
 
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Old 11-02-13, 12:51 PM
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Like this?

This is a brutal sketch, but is this the sort of thing you mean with the flashing before the window goes in?

Attachment 20394

While I'm surprised that siding is actually designed to let water in behind I do understand what you're saying here. This is news to me.

I went out last night to buy the building wrap where they had both Tyvek and the Pactiv stuff. Clearly I bought the Tyvek but now that I've had a chance to look at both I must say I'm surprised they're really in the same catagory of product. The Tyvek looks and feels like what's described in the product description. The Pactiv I would only describe as a REALLY CHEAP tarp material, Which got me to thinking about your, "I wouldn't cover a pile of wood with it" comment.

I walked over to where they were storing some newly delivered lumber that had not yet been unwrapped for sale. The stuff that they were using to cover 2x4's during transport (the stuff they throw away) appears heavier and more durable than the Pactiv house wrap that's supposed to protect your home. I was blown away by that.

(I sense the DuPont people will be smiling as they read this)

I'm completely unfamiliar with this Zip System so will need to do a bit of reading. Perhaps something to research when I side my house next spring...What about it did you find frightening?
 
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Old 11-02-13, 06:37 PM
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Yes... similar to that.........

Zip system seems like osb with a thin green painted coating. staples expose the osb when driven normally. Gives me the shivers to think how it will weather under porous siding like vinyl.
 
 

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