So house wrap is just a big nylon woven tarp?
Sum_Guy
| Posted in Energy Efficiency and Durability on
I had a look at those rolls of housewrap that lowes .ca sells. It’s just a big nylon woven tarp! And a very thin one at that. I thought it was more sophisticated than that. Like that black fabric you put down in your garden to keep the weeds from coming up.
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No it really isn't. Get a piece of Tyvek Commercial wrap or something similar. It's not woven and has completely different properties as to how it deals with moisture. If you aren't convinced you can always use building paper, but I wouldn't do so just because you didn't like the look of something at Lowes.
I think Tyvek is polypropylene. I’m not sure exactly, but I do know it’s not nylon. Tyvek is also a pressed (not woven) material. The stuff the box stores have is generally a Tyvek knock off, so similar properties.
Many useful products are pretty simple. Wood is just cut up pieces of tree after all. We built most of our houses with little more than plant parts! OSB is glued together bits of shredded tree! Paper is squished and bleached ground up bits of tree! None are all that fancy or complex, but all are very useful.
Bill
Hi Sam,
Tyvek HomeWrap is nonwoven, nonperforated, high-density polyethylene. There are lots of WRBs available, and they all seem to be manufactured a bit differently, with a variety of materials. You can learn about a bunch of them here: Nine Water-Resistive Barriers Worth knowing About
From what I hear from architects and builders that I trust, they can all work fairly well if they are installed right and equally importantly, if they are installed behind a rainscreen gap. One exception may be the perforated products--there is some independent testing that shows that do not block water very well.
Here's another important point:
To meet the ICC-EC acceptance criteria (that's the product evaluation service that the International Residential Code writers use), water-resistive barriers have to pass some tests to be approved for use. Unfortunately, they are not tested for a phenomenon that Peter Yost calls, "water held in tension." That's a geeky way of saying water trapped between the siding and the WRB for a period of time. I'm now starting to hear about failures of even some of the new self-adhering WRBs when there is no rainscreen gap and water gets held up behind the siding.
Here's a more in depth look at the role of a WRB: The Complicated Role of a Water-Resistive Barrier
Ok maybe it's not nylon but it looks and feels like the tarps you buy at any hardware or big-box store (ie tarp with metal rings for tying down, covering a car or a pile of fire wood, usually blue in color but comes in many colors, also a few different thicknesses).
If it's polyethylene then that's the same material that vapor-barriers are made from - yes? Like the "super-6" stuff ?
Smart vapor retarders aren’t made of polyethylene.
Polyethylene sheet IS a vapor BARRIER although. But it’s a solid sheet of polyethylene that is no porous. House wrap materials like Tyvek aren’t solid sheets, they’re made of densely pressed poly fibers, which are visible if you look closely — it looks like a flat tangle of little strings up close. House wrap is meant to be a vapor permeable air barrier.
Bill
"sum_guy",
I know which product you're talking about. It don't work... Or at least it doesn't look like it would work (I went out of my way not to buy it, so I've never actually used it) So I understand why you're questioning it. But I think your looking at the wrong product. My limited advice is to find the actual tyvek that the others here are talking about. Or preferably use a liquid applied wrb and window flashings if you can afford it.
Look at big Matt's video on it:
https://youtu.be/T55CEuKfdP8