Water Managed Walls

Primary Water Management: Initial Deflection

Secondary Water Management: Deflection, Drainage, Drying

When it comes to creating structures that last, we understand one of the biggest issues you face—moisture management. Water will penetrate the wall through any opening. It can be forced through exterior siding by wind, or simply leak through cracks. It soaks through mortar, stone, stucco, and brick. Air can even bring moisture into the wall in vapor form. Once inside the wall, water can cause significant damage, if it’s not properly managed. A typical residential wall is at least 25% wood, or cellulose. Wet wood can lead to mold and rot. Plus cellulose and fiberglass insulation lose R-Value when wet, decreasing their insulative performance over time. To stop exterior water from penetrating the wall and preserve durability and performance, structures need the protection of a water managed walls approach that combines exterior cladding, secondary weather barriers, and flashings.

Deflection. Drainage. Drying.

The Three D’s of Water Management

Deflection. Drainage. Drying. These are the basics of water management. Deflect water wherever you can. Make sure any water that is present can drain. And make provisions to dry out the areas that get wet. The techniques are simple, and with GreenGuard products and support, the tools are readily available.

Primary Water Management—Initial

Wall cladding, windows, and doors are a structure’s primary weather barrier, deflecting most wind-driven water. However, water will still get through them. Windows and doors leak. Water gets through seams and cracks in wood, vinyl, and fiber cement siding and soaks through reservoir claddings such as brick, stucco, and stone. Plus air passes through siding, carrying water. Where primary deflection fails, water is managed by secondary weather barriers.

Secondary Water Management—Deflection/Drainage/Drying

Weather-resistive barriers such as building wrap and flashing are secondary water management tools to deflect, drain, and dry water that comes through the cladding. By using a combination of GreenGuard flashings, building wraps, and sheathings, water can be deflected, keeping it from further penetrating the wall. Flashings deflect water at vulnerable points around windows and doors. Building wraps deflect water away from sheathing. One of our advanced wraps, RainDrop®, is designed with drainage channels that allow water to drain down quickly between the wrap and the exterior cladding, even if the cladding is nailed tightly to the wall. Additionally, every GreenGuard building wrap is permeable, meaning it “breathes” to allow moisture vapor to easily escape the wall cavity, facilitating the drying process. These tools are the means of preventing damage from water that passes the primary weather barrier.

Water Managed Walls

Water Management by Application

The primary components of water managed walls are outward-sloping sill plates and flashing, water and air barriers, drainage planes, and drainage channels. The specific approach you take will vary depending upon the type of exterior cladding you use.

Water Managed Walls: Brick

Water Managed Walls: Brick

Water Infiltration: Brick absorbs water. Water then soaks through to the back side of the brick and mortar. When properly installed with approximately 1” open space between the sheathing and brick veneer and with weep holes at the bottom, a drainage plane is created and no special drainage is needed.

Water Management Solution: A building wrap with water resistance keeps water from penetrating the wall.

MAX Building Wrap is one of the top products to use in brick applications because it provides the best air barrier and outstanding water holdout.

Water Managed Walls: Stucco

Water Managed Walls: Stucco

Water Infiltration: Stucco is installed wet and in direct contact with the sheathing, creating a problem for drying. Further problems result when building wrap or drainage wrap is applied without a drainage space.

Water Management Solution: The solution is a two-layer drainage system consisting of a bond break and a drainage plane. The bond break can be paper-backed lath or a layer of building paper or felt. Its purpose is to prevent the stucco from blocking the drainage space. A second layer of drainage wrap, attached to the sheathing, facilitates movement of water away from the wall.

Water Managed Walls: Stone

DC14 Drainage Mat provides an excellent secondary layer behind stucco or stone. The best practice is to install a layer of GreenGuard wrap before installing DC14. This makes secure flashing of windows and other openings easier. RainDrop® building wrap also works in the same application and provides drainage channels.

Water Managed Walls: Stone

Water Managed Walls: Stone

Water Infiltration: Manufactured stone veneer is installed against the wall, putting the mortar in direct contact with the wall sheathing. Further problems result when building wrap or drainage wrap is applied without a drainage space.

Water Management Solution: The solution is a two-layer drainage system consisting of a bond break and a drainage plane. The bond break can be paper-backed lath or a layer of building paper or felt. Its purpose is to prevent the mortar from blocking the drainage space. A second layer of drainage wrap, attached to the sheathing, facilitates movement of water away from the wall.

Water Managed Walls: Stone

DC14 Drainage Mat provides an excellent secondary layer behind stucco or stone. The best practice is to install a layer of GreenGuard wrap before installing DC14. RainDrop® building wrap also works in the same application and provides drainage channels.

Water Managed Walls: Vinyl Siding

Water Infiltration: While vinyl siding is an open structure that lets wind-blown rain come through easily, it just as easily drains and dries. So problems can be managed by proper installation of a good, water-resistant building wrap, in addition to proper flashing of openings.

Water Management Solution: Use of a drainage wrap or drainage mat enhances the water-shedding properties of the vinyl. A good 60-minute equivalent wrap, such as Classic Wrap, also works well in this application. Better still is MAX, which performs as both a water and air barrier.

DC14 Drainage Mat, which is ¼'' thick with drainage channels on both sides, moves water quickly away from vinyl siding. It can serve as a weather-resistive barrier if installed according to WRB guidelines. For even better protection against water, install any GreenGuard building wrap on the wall and cover with DC14.

Water Managed Walls: Foam-backed Vinyl Siding

Water Infiltration: Foam-backed vinyl siding installed directly over flat wall sheathing leaves no space for water to escape. Plus most foam backing is un-faced expanded polystyrene (EPS), which has a water absorption rate of approximately 4%.

Water Management Solution: Install a drainage wrap to move the water to the base of the wall. A drainage mat with thicker drainage channels is even more effective. Both approaches allow air movement in the space between the wrap and the siding to help facilitate drying.

RainDrop® Building Wrap is an ideal secondary weather barrier for foam-backed vinyl siding. It drains water and maintains space for air movement.

Water Managed Walls: Wood Siding

Water Infiltration: Wood siding is vulnerable to water infiltration through seams, as well as absorption through the wood. One approach to handling this is to install wood siding or shakes over wood furring strips to create drainage space or a “rain screen” wall. However, a secondary weather barrier is still required to protect the wall sheathing.

Water Management Solution: Install a drainage wrap to move the water to the base of the wall. A drainage mat with thicker drainage channels is even more effective. Both approaches allow air movement in the space between the wrap and the siding to help facilitate drying.

RainDrop® Building Wrap is an ideal secondary weather barrier for wood siding. It drains water and maintains space for air movement. Unlike embossed or “crinkled” drainage wraps, the drainage channels do not crush when the siding is nailed tight.

Water Managed Walls: Wood

DC14 Drainage Mat, with drainage channels on both sides, provides even greater drainage and air movement behind siding. It is an excellent choice for wood siding because it resists wood chemicals. The best practice, when windows are to be flashed, is to install a layer of GreenGuard wrap as a secondary weather barrier before installing DC14.

Water Managed Walls: Fiber Cement Siding

Water Managed Walls: Stone

Water Infiltration: Water can soak through fiber cement siding and especially leak around it, particularly at corners and joints. Fiber cement is also nailed tightly to the wall, leaving the water no way to get out. Caulking may block water infiltration on new installations, but the best long-term protection is a secondary weather barrier.

Water Management Solution: Install a drainage wrap to move the water to the base of the wall. A drainage mat with thicker drainage channels is even more effective. Both approaches allow air movement in the space between the wrap and the siding to help facilitate drying.

Water Managed Walls: Stone

RainDrop® Building Wrap is an ideal secondary weather barrier for fiber cement siding. It drains water and maintains space for air movement. Unlike embossed or “crinkled” drainage wraps, the drainage channels do not crush when the siding is nailed tight.

DC14 Drainage Mat, with drainage channels on both sides, provides even greater drainage and air movement behind fiber cement siding. The best practice, when windows are to be flashed, is to install a layer of GreenGuard wrap as a secondary weather barrier before installing DC14.

Water Managed Walls: Flashing

Water Managed Walls: Stone

Windows, doors, service penetrations, and intersections of roofs, decks, and porches all need to be flashed to keep water out of the wall. The rule of thumb is “over, down, and out” to allow water to take the path of least resistance and move away from the wall.

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