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DELTA-DRY Ventilated Rainscreen


Ventilated Rainscreen: The innovative approach of solving moisture problems in building envelopes. The ideal protection behind adhered manufactured stone veneer, conventional stucco, and other absorptive claddings.
Proper ventilation is key for wall performance and the prevention of moisture accumulation.
Need help with ventilation details? Go to the "Downloads" tab and download our comprehensive standard Architectural Details. Everything you need to know to ventilate DELTA®-DRY can be found right there.
Still not sure or want your details reviewed? Call the Tech Hotline at 1-888-433-5824 or e-mail us at
We are glad to help!

Evaluation Reports & Building Code Approvals

ICC-ESR # 2987 Moisture Drainage System used with exterior cement plaster or adhered masonry veneer walls

BMEC Authorization No. 05-06-310


The structured membrane provides drainage and ventilation, as well as a complete capillary break behind the cladding. It protects the building envelope from bulk water intrusion (i.e. wind driven rain), and manages water leakage through the cladding. As well, DELTA®-DRY captures and drains transient moisture migrating through the wall structure. DELTA®-DRY provides an air-gap on the interior and exterior side of the membrane for drainage and ventilation.

DELTA®-DRY allows water vapor, driven from the interior to the exterior of the structure, to escape through the ventilated air space between the sheathing board and the membrane, while minimizing the potential for condensation that could cause damage within the building enclosure.

The membrane provides excellent drying potential through ventilation behind any approved exterior cladding. At the same time, it impedes solar-driven moisture towards the interior of the structure, such as occurs with absorptive cladding materials like adhered manufactured stone veneer, stucco, cement board siding, brick veneer, etc.


DELTA®-DRY is a 3-dimensional membrane made out of a special high-density polyethylene that provides two-sided drainage and ventilation through its unique dimple and groove design.


DELTA®-DRY is installed outboard of the water-resistive barrier over sheathing board. It also provides excellent performance if installed in lieu of a conventional WRB, where building authorities allow this type of application. The material cuts easily with a utility knife. Seams are simply butted together with no overlapping necessary. Exterior cladding material can be installed as usual right on top of DELTA®-DRY. For further details please check the installation instructions.

Technical Data

Product name DELTA®-DRY
Color silver-gray
Material High-density polyethylene (HDPE), stabilized (oxidation & UV)
Dimple height apprx. 0.42" (10.53 mm) ASTM D1777-96(2002)
Drainage efficiency apprx. 95% ASTM D2273-03
Compressive Strength                 93 kPa (1,946 psf) @ 8 % strain ASTM D6364-06
Fire Resistance


DIN 4102

Flame Spread



Smoke Developed



Water Penetration Resistance 118 psi (813 kPa)
AATCC 127-1995

Water Vapor Transmission

22 ng/(Pa s m²)

ASTM E96, Method A                                   

Vapor Permeance

0.385 perms [grains/h/ft²/in Hg]

ASTM E96, Method A                            

Contact surface of rainscreen to WRB

9% (91% open)

Contact surface of rainscreen to cladding

20% (80% open)
Chemical properties excellent chemical resistance, rot-proof
Toxicity non-toxic, non-polluting
Temperature range -22°F to +176°F  (-30°C to +80°C)
Fungi Resistance Pass ASTM C 1338
UV Aging Pass AC356-2009
Roll weight approx. 17.6 lbs  (8  kg)
Roll length 50'     (15.24 m)
Roll width 3' 3"   (1.0 m)
Service life expectancy

> 20 years (at pH between 4 and 9). Do not expose to UV light for longer than 30 days.


What does DELTA®-DRY do?
DELTA®-DRY is a premium ventilated rainscreen that helps protect the structure of the building by providing moisture control in the walls and allowing for ventilation and drying of the building enclosure. It creates a continuous drainage path outside of the sheathing boards to prevent the build up of condensation. As well, DELTA®-DRY adds drainage behind the wall cladding. It allows walls that get wet to dry as quickly as possible to prevent mold, mildew and structural deterioration.
DELTA®-DRY will resist the inward movement of solar driven moisture.

How does DELTA®-DRY provide drainage?
DELTA®-DRY has a unique dual sided 3-dimensional drainage profile with channels that guide liquid water that hits it downwards and out of the wall where it will do no harm.

How does DELTA®-DRY provide ventilation?
DELTA®-DRY has a unique dimple structure that creates maximum free area with minimum contact with the wall sheathing. With a contact area of less than 9%, air may move freely across the wall in all directions. The ventilation cavity must be open at both the top and the bottom of the wall for any ventilation to occur.
Several natural forces will create ventilation in the cavity. Differences in air pressure (wind) will move air through the ventilation cavity. Normal convection currents within the wall cavity will also move air. Warm moist air will rise and exit through the top ventilation while cooler drier air will move in through the bottom ventilation to replace it. Both of these natural forces will cause air exchanges within the wall cavity.

Is it important to have open ventilation at the top and the bottom of the wall?
It is very important to have open ventilation at the top and the bottom of the wall. This is critical to the proper functioning of DELTA®-DRY. While trim and/or a drip edge may be necessary along with a bug screen to keep out unwanted intruders, the ventilation will allow the drying effect of air moving through the cavity to occur. For buildings more than 2 stories high additional ventilation through a wall transition detail is recommended (see download tab for details).

What is “drying capacity” and why is it important?
Drying capacity refers to the ability of a wall system to manage and rid itself of water and water vapor. The higher the drying capacity of a wall system, the better the system is able to cope with moisture within it. The better the ability of a system to cope with moisture, the less likely the moisture is to cause decay, rot and mold in the wall.

What is “solar–driven moisture”?
Solar-driven moisture is an effect that occurs on absorptive claddings such as conventional stucco, manufactured stone, natural stone, clay brick, and cement board siding. Water from sources like rain, snow or lawn irrigation is sprayed onto these claddings that easily absorb it. The sun then hits the surface of the cladding and begins to heat it up. The moisture remaining on the surface evaporates, but the moisture within continues to heat up as the sun continues to heat the cladding. The water vapor pressure increases within the cladding and the vapor pressure differential forces the moisture to move inward where it can wet the structural components of the wall if there is no barrier to prevent it.

Is DELTA®-DRY a vapor barrier?
No. DELTA®-DRY doesn't act as a vapor barrier in the system. While it is true that DELTA®-DRY is impermeable to water vapor, it must be ventilated. When it is ventilated, it cannot form the continuous barrier that would be necessary to act as a vapor barrier.

Is DELTA®-DRY an air barrier?
No. DELTA®-DRY is not an air barrier in the wall system. While the special high density polyethylene can prevent the movement of air through it, the way it is detailed and the necessity for ventilation does not permit it to be designated the air barrier in the system.

Is DELTA®-DRY a radiant barrier, too?
No. Although DELTA®-DRY is grayish-silver color, it does not act as a radiant barrier in the wall system. However, it absorbs far less solar heat radiation than conventional building paper.

Is DELTA®-DRY a water resistive barrier?
While DELTA®-DRY does not allow liquid water or moisture vapor to pass through, its primary purposes are to provide drainage, ventilation, a capillary break, and humidity moderation.

Can DELTA®-DRY be used in conjunction with a water resistive barrier?
In most jurisdictions, DELTA®-DRY must be used in conjunction with a water resistive barrier. In general, it is placed to the exterior of the water resistive barrier in the wall system. The WRB is installed according to the manufacturer’s recommended procedures. The DELTA®-DRY is installed over top according to the installation instructions.

Can DELTA®-DRY be used without a water resistive barrier?
In Ontario, Canada, the Building Code allows DELTA®-DRY to be used stand alone without the addition of a water resistive barrier. The performance qualities of the DELTA®-DRY are unaffected by the absence of a water resistive barrier. Note that the installation procedure changes slightly compared to the installation of DELTA®-DRY as a rainscreen, predominantly due to requirements for flashing of window openings and other penetrations.

Can I still upgrade my insulation?
Insulation can still be upgraded if DELTA®-DRY is being included in the wall system. Make sure that any additional insulation is installed to the inside of the DELTA®-DRY.

Will DELTA®-DRY make my home more energy-efficient?
DELTA®-DRY will not alter the energy efficiency of a well performing wall. However, the inclusion of DELTA®-DRY in any wall system will help ensure that the wall continues to perform in the manner in which it was intended. It will help keep the structural components dry thereby adding to their life expectancy. DELTA®-DRY will help keep insulation dry which will allow it to keep up its performance.

Will DELTA®-DRY make my house a healthier home?
DELTA®-DRY will help prevent the occurrence of mold and mildew within the wall. Because both mold and mildew are thought to be major issues affecting the health of those living in the home, it can help make the house a healthier home.

Has DELTA®-DRY been tested to prove it works?
Yes. The hygro-thermal performance of DELTA®-DRY has been extensively tested by The Oak Ridge National Laboratory (ORNL), as well as by the Building Engineering Group at the University of Waterloo, and Building Science Corporation (bsc). Reports are available on inquiry.

Is DELTA®-DRY easy to install?
Yes. Easy-to-follow installation instructions for the application of DELTA®-DRY over a weather resistive barrier (WRB) are available right on this website. No special skills or tools are required. Simple equipment such as safety items, hammer, tools for measuring and alignment, a knife for cutting, and 1 ½” large head roofing nails are all that are necessary for the basic installation. Other required materials will be bug screen, flashing, and drip edges for detail areas around the top and bottom ventilation areas. So long as the DELTA®-DRY is being installed over a WRB, very little other detailing is required.
If DELTA®-DRY is being installed as a stand alone system (without a WRB) in Ontario, Canada, please contact the technical department at 1-888-DELTA4 (1-888-433-5824) for the appropriate installation instructions for your application.

Are there any special considerations for claddings such as conventional stucco or manufactured stone?
Yes. Because these materials are highly absorptive claddings, DELTA®-DRY is especially suited for use behind them. These materials tend to hold water and are therefore particularly susceptible to vapor drive from solar-driven moisture. DELTA®-DRY can significantly enhance the drying capacity of these systems.
This is not the only special consideration. Many jurisdictions require the use of two layers of a weather resistive barrier (WRB) in these systems. When two layers of a WRB are required, it is best to put the DELTA®-DRY in front of the first layer and behind the second layer. Always check your local building requirements for the cladding materials selected.

DELTA® is a registered trademark of Ewald Dörken AG, Herdecke, Germany.


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