Selecting the Right Drainage Mat

furring strips as rainscreen drainage mat

The Problem with Furring Strips

In his article Mind the Gap, Eh! Dr. Joseph Lstiburek established the need for a “drainage space” (a gap or void) behind the veneer and in front of the weather resistant material on the backup wall to alleviate moisture-related failure of the building envelope. This gap or void can be created with furring strips, but there are inherent challenges with this method.

There are several inherent problems with this type of rainscreen drainage system.

Too many components (cost issue)
Too labor intensive (cost, time, and complexity issues)
Consistency and quality of final system cannot be guaranteed

Download Drainage Mat vs. Furring Strips Article

Another Damming Problem - Weep Screeds

Another factor that negatively impacts most common systems is the reliance on weep screeds that don't match the drainage capacity of the wall. New polymeric coatings on stucco attempt to seal out water, but in reality seal up the bottom terminations so that weep screeds can't weep. A rainscreen system must be detailed to drain at terminations.
Learn more about Weep Screeds here.

Why Use a Manufactured Drainage Mat

The new technology that is attempting to improve the rainscreen drainage detail is the use of “mat” materials. Most of these mats come in the form of roll stock. They differ from one to another in drainage efficiency, compressive strength, and ease of installation. What they all bring to the construction industry and specifically the exterior building envelope segment of the construction industry is ease of installation and in most cases a more predictable cost effective rainscreen drainage plane. When choosing which one of these new rainscreen drainage mat (drainage plane) technologies to use in your next project, select the one that best suits your veneer/rainscreen type, and a one that comes from a manufacturer who will work with you to design the right moisture management system for your project.

	MTI Sure Cavity™	Meshes	Entangled Filaments	Dimple Boards	Textured Housewrap
Predictable Drainage Channels
Resists Compression
Prevents Wavy Walls, Fastener Breakthrough
Creates Rainscreen Drainage Gap
Vapor Permeable
Over 96% Recycled Material