Weather Resistant Barriers (WRB) Reduce Moisture In The Home.

Weather Resistant Barriers (WRB), a key structure to long lasting siding repairs is a moisture and air resistant envelope created with high-performance building wrap, specialized fasteners, penetration gaskets and flashings, polypropylene seam tape, and butyl flashings.

There are many benefits of WRB’s.  Besides protection against water infiltration and better control of air flow WRB’s can improve your home’s energy efficiency and lower your energy costs. They also are essential in prevention of rot, mold, and mildew and help enhance your indoor air quality. In the past homes used tar paper and the newer composite materials truly outperform this dated material and are longer lasting and safer.

A few Portland rain ready Weather Resistant Barrier options are:

DuPont Tyvek Drainwrap

Drainwrap helps provide enhanced drainage behind claddings such as primed wood (all six sides), fiber cement siding, and foam board applied over flat substrates.  Vertical grooves on the surface of Tyvek® DrainWrap™ make it a superior moisture barrier, engineered to channel bulk water away from wall systems and drain safely to the outside.  Its unique structure helps hold out bulk water, while allowing water vapor to pass through it, promoting drying in the wall system, which can help prevent mold and water damage.  This also helps prevent air movement through the walls, contributing to a more energy efficient home.

Benjamin Obdyke Hydro Gap

This product effectively eliminates excess moisture which protects against the damaging effects of mold and rot. Hydro Gap sheds bulk water away from the structure, up to 100x more than standard house wraps on the market.

HardieWrap® Weather Barrier

HardieWrap is a high performance weather barrier made by James Hardie, the top producer of siding in the United States. HardieWrap weather barrier offers a balance of water resistance and breathability.  This allows moisture from inside your home to escape which, in turn, keeps the area within the wall dry.

Moisture and water infiltration is a significant problem in the Pacific Northwest, especially in Portland.  As a result Oregon has adopted a new code to help eliminate moisture infiltration.  A weather resistant barrier (WRB) is your home’s best defense against the elements.

Water Resistant Barrier
SFW Construction is a Portland siding contractor certified by Dupont and an expert in installing weather resistant barriers (WRB). What’s the point of spending money on beautiful exterior finishes if your home isn’t protected from the elements. SFW Construction does it right the first time.
Oregon codes require the use of a Water Resistant Barrier.

How a Siding Rain Screen protects from the Portland Weather.

Protecting your property is of vital importance.  Other Portland siding companies may offer cut rate and cut corner options for protecting your investments but at SFW Construction we are well acquainted with best methods and well as with the Oregon Repair Code.


A siding rain screen is an important part of siding replacement and siding repair.  A rain screen is constructed by fastening wooden boards vertically on top of the weather resistant barrier (WRB) to provide an air gap between the building and the siding creating a drainage plane.  Any moisture getting behind the siding system can easily escape by draining downward.  A rain-screen is seen as one of the most effective ways to keep water from infiltrating a building, but it can also be the most expensive.


At SFW Construction LLC we excel at being cost effective without compromising the quality of the project.  Our rain screens follow this model.  A siding rain screen should encourage air circulation behind the siding using cost effective materials and specs that are up to code.
Rain Screen Wall System
exterior siding portland, pdx

New Oregon Siding Repair Code

Below is a link to the new Oregon siding repair code that was adopted on January 1st 2010. The new code requires that there is at least 1/8″ gap between the siding and the weather resistant barrier (rain-screen). It’s important to consider Oregon’s new siding regulation when completing a siding or dry rot repair project.

There are a few exceptions to this rule.
The space is not required where:

  • Window sills are equipped with pan flashing.
  • An enhanced drainage system is installed that meets 75% drainage efficiency.
  • It is matching the existing exterior finish as in additions, alterations, or repairs.

These details are crucial to siding repair and replacement.  See here for a full description of the code.

Be sure that your siding contractor understands the Oregon siding repair code and does the job right the first time!  Though you may want to familiarize yourself with this document, it is not your job to know these specifications, it is ultimately the responsibility of the contractor you hire to work on your home.  At SFW Construction LLC, we make sure to research all the latest building codes and keep our practice up to spec while passing along superior customer service and quality craftsmanship to you – our valued customer.