Construction Knowledge Series: What is "WRB"?

“WRB” is a common acronym for Weather Resistant Barrier or Water Resistant Barrier.

WRB goes on the exterior of a house or building underneath the siding system. A building’s WRB protects the structure from water intrusion. Most people believe that the siding is what protects a building from water. This is partially true, but it would be more accurate to say the siding protects the WRB which protects the building from water. Siding can include Hardie siding, metal panels, and masonry veneer among other products.

The photo below shows my home being re-sided this summer and you can see the Tyvek Homewrap (a WRB) installed before the Hardie lap siding. Hardie board and many other siding systems are not 100% waterproof. If any water gets behind the siding, it will hit the WRB, run down it and stay off the structure. 

When it comes to residential and lots of commercial work, Tyvek is the industry leader and most common brand of WRB. Tyvek is synonymous with WRB and is often used interchangeably with the term WRB, especially in residential construction.

Now you know why there's that one house down the street that's had exposed Tyvek for the past year. It's not right, but their house is probably more protected that you'd think.