Product Review: DensElement Barrier System by Georgia Pacific

Moisture resistant gypsum panels have been around for more than forty years. When Georgia Pacific introduced fiberglass faced gypsum board over twenty years ago they revolutionized the sheathing industry. They have been consistently innovative and have currently released their DensElement Barrier System sheathing and teamed with Prosoco’s FastFlash for their panel joints. No doubt this system will save construction time and installation quality. But like all products there are a few refinements that need to be addressed in order to work with other envelope components.   

Cladding Systems need to provide self-seal fasteners with DensElement. Normally, designers and contractors have primarily depended on the liquid air barriers for assistance in sealing their fasteners.  Screw type fasteners provide some self-seal but installers continue twisting even though they missed the stud creating air holes. 

Isolate cladding systems from DensElement. Separate to prevent ponding. Avoid any cladding attachment or design that may trap moisture against DensElement.

Wall cavities with sloped or flat DensElement surfaces require membrane flashing to minimize ponding.  See manufacturer’s literature.

Weeping and venting of wall cavity is always a priority. Even though DEBS panel is more moisture resistant than previous sheathings it depends on limited moisture.  

Membrane flashing of fenestration openings is still a requirement: doors, windows, louvers, etc.  

Flash exterior wall penetrations such as MEP with membrane or fiber reinforced liquid flashings. Penetrations are bumped often by other trades when working around them even after the cladding is installed.

DensElement is a great step in the right direction but the construction industry needs the following in order to improve construction schedules and quality. We need a sheathing panel that addresses all weather resistive barriers (continuous air, moisture and thermal)!

 

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Suburbia is the Future of Sustainability

Answers for Architecture

Answers for Architecture

One of the influences that is impacting architecture is the future of urban versus suburban debate. Urban proponents are convinced that they are right but are they? Recent studies revealed that more than 50% of their inhabitants would like to move out. Suburbia's low rise homes and low rise multi-family housing with surrounding landscape can provide many, healthy, quality, sustainable amenities that very few urbanites can experience. Here are a few: 

Cleaner Air These mini-farms and parks with abundent vegetation absorb, retain and cleanse CO2 emissions providing an environment for raising healthy children. 

Low Impact Development minimizes storm runoff; easily recycling rainfall with minimal retention methods like brick pavers allowing for evaporation and absorption process, naturally recharging rainfall and aquifers.  

Mini-Parks Front, back or side yards can provide local recreation that stimulates creativity and recreation; sustaining health children as well as adults. These yards, plants and flower beds nurture the adult soul as well as the body.  

Mini-Farms Fresh, healthy free vegetables and fruit can be raised. 

Net Zero along with passive house is the mantra of the decade, working towards energy efficient homes. New as well as retrofitted existing homes can provide for their own energy needs from solar collection,  potentially having excess for urbanites. These single family homes for example can adapt to seasonal climate changes successfully by simply opening windows for ventilation.  

Transportation for suburbs is becoming more fuel efficient and less polluting along with the development of mass transportation. The culture change, working from home, has the potential to improve obviously improved commuting issues and needs.

Wildlife Habitats in backyards are being encouraged, certified, providing food, shelter and nesting for birds, insects and other critters. .

Seventy percent of densely populated, hard surface, high rise dwelling urban areas like New York and Chicago  cannot provide or compete with the above listed suburban amenities. 

New York, the City of Shadows

New York, the City of Shadows

Densely populated urban buildings preventing Net Zero objectives should be removed, replaced or retrofitted.

Eco-City snippits-and-slappits.blogspot.com All buildings should maximize solar harvesting,  generate fresh air and provide local food source

Eco-City snippits-and-slappits.blogspot.com

All buildings should maximize solar harvesting,  generate fresh air and provide local food source

 

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The EPA's LID agenda is harmful to existing and new architecture unless the building and site is properly drained. . 

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Best Practice No. 4: Reject the Camel's Nose, Design with the Perfect Wall Design

Building Science.com Diagram

Building Science.com Diagram

The Perfect Wall Concept and resulting Perfect Wall should be in your best practice “tent.” If not, your tent will be filled with more than just the camel’s nose. The Camel nose metaphor is “a situation where permitting some small, seemingly innocuous act will open the door for larger, clearly undesirable actions.” One harmless act or change with a product, complex wall design or its installation can render it ineffective and unhealthy. The Perfect Wall Concept is relatively simple, effective and constructible.

One would think the concept is common knowledge after almost a decade of its promotion by Dr. Joe Lstiburek and scientifically verified by Dr. John Straube. But according to ongoing installation and designer detailing problems, it is not. More verifiers (Consultants, Cx Agents) are being utilized to make the design and construction process accountable.

The Perfect Wall Concept protects and insulates the weather resistant barrier, provides an effective life cycle performance, keeps moisture and condensation out of the building and can be used in any climate. The concept is adaptable to roofs and foundations, providing the same benefits. It can be ventilated or a structural insulated panel (SIP). See included Building Science.com diagram.

Ventilated wall  or cavity allows more design flexibility than a SIP system. It is a necessary design component of the perfect wall and it is a simple concept. The ventilated cavity wall has been utilized successfully by this author since the 1970s to protect buildings by removing unnecessary moisture from the cavity.

The Rainscreen is what I consider a high performance ventilated wall that adheres to the Perfect Wall Concept. When energy efficiency requirements were applied and scientifically documented by the Canadians they started calling it the rainscreen. The weather resistant barrier became air tight and the insulation moved to the cavity, providing more efficient continuous, protected and uninterrupted insulation.  

The pressurized rainscreen controversy has purposefully been excluded from this article.  There are advocates of the system, but this author finds the approach unnecessary in climate zones 2-5 (if not all) and complicated with conflicting opinions by building science advocates.

The rainscreen is the Perfect Wall. The following Perfect Wall has developed over the last seven years as the best practice for exterior wall design. Starting from the exterior face and moving toward the interior, the components or layers are…  

Cladding provides the exterior wall’s durable protection, primarily, from windblown debris and ultra violet light degradation. The Perfect Wall allows the use of any type of cladding.

The responsibility of the Air or Drainage Cavity is to ventilate and drain, removing unwanted moisture quickly. The air cavity, vented from the top and bottom, allows free movement of air to dry out damp surfaces. The cavity separates the cladding from the thermal barrier.  The cavity also allows for deviations of construction tolerances such as brick,  widths varying from 3/8” to ¾”.

The Thermal Barrier is to be continuous, connected to roof, slab and basement insulation, adjacent to and protecting the weather resistant barrier from the climate. It should be in one location, not two;  ensuring moisture condensation is on the exterior, minimizing installation expense and protecting it from future building renovations or additions.

The Weather Resistant Barrier (WRB) supported by a substrate is to be in one location only, minimizing redundant barriers and installation errors. These components should always interface with the roof, foundation and basement WRB to provide a continuous air and moisture protected building. Its perm rating should always be similar to its substrate’s, minimizing destructive condensation within in the wall.  

Structure supports the wall components and roof structure. It can be metal studs with gypsum sheathing, CMU, etc...

Interior Substrate such as gypsum wall board allows moisture and air movement and supports finishes such as latex paint, wood paneling, etc.

Currently there are efforts being made to combine the layers noted above for improving installation time. There are pros and cons depending on how they are detailed.

The actual design of the Perfect Wall components should always include a basic understanding of  building science, constructability, construction tolerances, owner maintenance requirements and material durability to name a few.

We will describe each of these Perfect Wall layers more thoroughly in future articles.    

The Perfect Wall is the best practice for ninety percent of the building enclosures. It helps us design  effectively for any climate change even though we have 6000 years of limited written documentation. Build your reputation and leave a sustainable, effective building for future generations. Adhere to the Perfect Wall design principle, reject those camel noses.

More best practices to come. If you agree, share this article. Let's improve enclosures together.