Before Choosing a Weather Barrier Membrane, Ask these Questions

A weather barrier membrane is an essential part of the building envelope. Choosing the best one for a particular project depends on many factors, from the type of performance you’re looking for to specifics about the building’s design and climate zone. To help guide your weather barrier membrane selection, we’ve put together some key questions that should be asked at the start of every project.

In today’s construction market, air barriers generally are available in sheet applied, self-adhered and fluid applied. Each has its advantages and disadvantages, depending on the answers to the following questions:

What’s the project climate zone?

According to ASHRAE, North America has eight different climate zones. Each has its own conditions that will affect air/weather barrier performance in terms of moisture and vapor control as well as energy efficiency. The temperatures and relative humidity (RH) to which the building will be exposed matter greatly.

What are the wall assembly requirements?

How will the air/weather barrier work within the wall assembly? For example, what kind of substrate will the barrier be adhered to? Are there complicated architectural details or irregular surfaces? If so, a fluid-applied membrane may make more sense. Where is the insulation located? Is it all in the stud space, all in wall cavity, or a combination of the two? Does the wall need to comply with NFPA (National Fire Protection Agency) 285?

What are the back-up wall assembly requirements?

Are there studs with exterior sheathing? Are there CMUs with masonry ties set into the mortar joints? A fluid-applied air/weather barrier will make more sense for CMUs with masonry ties, since installing a sheet applied membrane around masonry ties will be difficult and time-consuming at best. In general, fluid-applied barriers will be the better choice for buildings with complex geometries and transitions.

What’s the building type and purpose?

Is it a low-rise, residential structure? Is it a high-rise vertical structure with more demanding interior environmental expectations?

What about building details and penetrations?

Does the building design have many architectural details? Are there a lot of penetrations – windows, doors, pipes – or relatively few? If there are a lot of window openings, a sheet-applied membrane and flashing probably makes more sense. If there are much fewer window openings, a spray-applied membrane will be a much more efficient installation choice.

Have other questions or concerns?

As you can see, selecting the best weather barrier membrane involves a lot of questions and considerations. If you need some advice on your next project, don’t hesitate to schedule a meeting with one of the building envelope experts at Henry® Company. Backed by 80+ years of industry-leading innovations, our Building Envelope Systems® offer a wide range of fully compatible products and solutions to meet any project requirement.