Building Codes Address Bulk Water Management

CodeWatcher Typar Bulk Water

Codes drive adoption of drainable building wraps as solution to manage bulk water.

In many areas around the country, building codes are driving the need for better moisture management solutions. The International Residential Code (IRC) requires the use of water-resistive barriers, but some states have added even more prescriptive measures to their codes that now include the use of drainage planes and others are expected to follow.

Thankfully, advances in material technology have resulted in innovative solutions for protecting our homes and buildings from the elements while allowing them to both release vapor buildup and drain bulk water. And with a growing number of products hitting the market to address this need, it’s important to understand how each performs in order to specify the right building wrap for your project.

Drainage Efficiency

Drainage is widely accepted as one of the most effective measures for reducing damage due to rain penetration and is a critical component in allowing a building wrap to do its job, particularly in keeping walls dry. Historically, drainage has been achieved through the use of furring strips that separate the wrap from the structural sheathing and framing, but new technologies have emerged that are helping to simplify this process.

The drainage efficiency of a building wrap is generally tested in accordance of ASTM E2273. In simple terms, this test involves spraying water onto a wall assembly and measuring its collection over time. However, given the variety of drainable building wraps available, how quickly bulk water is drained can vary significantly.

Today’s most advanced building wrap products feature integrated drainage gaps through creping, embossing, weaving or filament spacers. These new products eliminate the need for furring strips, helping to reduce material costs and streamline installation.

Making the Right Selection

With so many options to choose from, how do you know what type of weather protection is best for your project? There are a number of factors to consider.

A key consideration is the type of cladding being used. When installing vinyl siding, which has built-in drainage holes and fits loosely on the wall, an ordinary smooth-faced building wrap should provide adequate drainage. However, tightly fastened cladding such as cedar siding or fiber cement board might allow water trapped between the siding and a smooth building wrap to pool and could eventually make its way through the building wrap and into the framing. These are cases where a drainable wrap would provide significant benefit. Reservoir claddings such as brick, stucco and stone present another set of issues. In these applications, it is imperative to separate the cladding from the rest of the assembly with a capillary break, which can be an airspace or a material that sheds water or does not absorb or pass water.

Geography and climate are important, as well, specifically as it relates to annual rainfall. As a rule of thumb, the Building Enclosure Moisture Management Institute recommends that any area receiving more than 20 inches of annual rainfall should incorporate enhanced drainage techniques.

While we can’t completely stop water from getting into walls, advances in building wrap technology are a welcome way to help ensure potential damage from water intrusion is mitigated. And with a variety of drainable products to choose from, each offering a different approach to bulk water drainage, builders and contractors have many ways to keep walls dry in any climate or condition.