I’ve heard this question several times over the years building custom homes in Wilmington, NC; “why do you use Tyvek® on your houses?”
In the past, we would only use felt paper (sometimes called tar paper). Felt paper was used for many many years as the go to choice for protecting wood walls from rainwater, and it was very effective.
So why did we switch to Tyvek®?
We actually resisted for many years when housewrap was first in vogue, because we were not convinced that it would work effectively long term, when we had proof that felt paper had long term staying power.
The impetus to switch initially had nothing to do with long term endurance, but was all about windows and window warranties. Window manufacturers began issuing official installation guidelines demanding housewrap and housewrap tape, or else the warranty would be voided, at which time we reluctantly switched from wrapping our houses in felt paper to Tyvek®.
Over time, as we began to learn more about the science of how buildings work, and about how to make our houses more comfortable, we began to see the advantages of housewrap. A smart housewrap will keep rainwater out while allowing some water vapor to pass through. This is super important in hot humid climates such as what we have in Wilmington, because we need moist air to be able to move through our walls without being impeded by a vapor barrier, which can cause rotten wood and mold inside our walls – something we as builders are constantly seeking to guard against.
Another question I have heard often, this mostly from building supply stores, is “why do you use Tyvek® when there are cheaper options?”
Another good question.
1) Science: I saw a demonstration a few years ago by a leading building science expert who wanted to test whether the resins in wood sidings could break down housewrap, so he boiled cedar chips to create a resin “stew”, and poured it over several brands of housewrap. Only two of the brands held up to the test; Tyvek® and Typar®. Between these two, I judged Tyvek® to be a better fit for our climate due to it’s vapor openness (more open than Typar®).
2)Experience: My experience with every other housewrap I have used (other than Typar®), is that they had a tendency to stretch easily, which pulled the fibers apart (read: big holes), while Tyvek® stayed intact. I’ve also noticed that other housewraps, left exposed to the elements for a short while, begin to break down from the UV rays and fall apart. Not good.
This is possibly more information than anyone cares to know, but now you know why we use Tyvek® on our custom homes in Wilmington, NC.