Permeable ICF wall system at GRuB Education Center
Search code innovationsEnter a keyword to search for code innovations.
Garden Raised Bounty is a non-profit environmental learning center built upon the generosity of a whole community. The first-floor walls were constructed with Faswall ICF’s (insulated concrete forms), creating an efficient open-diffusion permeable wall system. Non prescriptive parts to this project include custom engineering for an ICF, energy code compliance an non prescriptive wall assembly.
The Builders and Designers worked closely with the City of Olympia to ensure code compliance. The permitting process wasn’t challenging in this specific instance but could have been if the code official weren't familiar with the product.
|Code Requirement||Compliance Path|
Structural: IRC 611 Exterior Concrete Wall Construction
|Custom Engineering by Harriet Engineers|
|Energy Code||Effective R value of Faswall ICF as provided by Faswall|
Vapor Retarder: R 601.3 Vapor Retarders
Vapor Permeable wall system study including Durisol (equivalent to Faswall)
Planning their new headquarters, this non-profit organization looked for a timeless and efficient way of building that would reflect their commitment to natural stewardship. The new 2,928 sq ft farmhouse was planned with special care to make it as green and energy efficient as possible. They chose Faswall® permeable ICF (insulating concrete form) system for the first floor wall framing to provide a healthy, non toxic indoor living space that greatly reduces energy costs.
With plasters/stucco finishes FASWALL creates a breathable wall system. The material is hydroscopic; it absorbs and releases water vapor in a “sink effect”, thereby evening out the indoor humidity and eliminating moisture buildup in the wall. Even if water infiltration should occur (from roof leaks, windows, etc.), that moisture can escape. The walls are highly alkaline so create an inhospitable environment for mold growth, great in the Pacific Northwest where mold growth is common. Understanding this, the code official approved the design without the required vapor retarder.
Manufactured by ShelterWorks Ltd. in Oregon, this ICF block is made from 85% recycled wood chips (from pallets) and 15% cement. The blocks are delivered with insulation inserts made from mineral wool (recycled slag from steel production and basalt rock spun at high temperatures). FASWALL is non toxic and all chemical additives, drywall, wraps, and extra insulation can be avoided. These walls provide a continuous insulation envelope without the heat loss common is conventional construction. The interlocking tongue-and groove end design keeps the wall forms in place. Rebar is set both horizontally and vertically within the stacked forms prior to filling the cores with concrete. This creates a “post and beam” grid effect which makes the wall exceptionally strong. Click here for more details on structural design and characteristics.
The blocks are impact resistant, have a four hour fire rating no flame spread, no smoke development (ASTM C-119-88, E-84-89a; test done without insulation inserts), water resistant, and contain no foam or polystyrene. Faswall has a great sound proof quality (ASTM E 90-90), STC rating of 55: creates an exceptionally quiet indoor space. Insulated thermal mass into the living space contributes to lower temperature swings and significantly reduced heating and cooling costs. Very low life-cycle energy cost.
Design / Build Process
The staff at Grub envisioned a structure that would endure much use and many generations; enhance and protect ecosystems and biodiversity; improve air and water quality; reduce solid waste; conserve natural resources; reduce operating costs; enhance asset value; improve employee productivity and satisfaction; reduce energy use; thermal and acoustic environments; and contribute to overall quality of life.
The GRuB Farmhouse design was a collaboration on every level. Early on, they brought in Living Shelter Design from Issaquah to facilitate a design charette where staff, youth, board members, and volunteers had the opportunity to contribute to the overall vision for the site and Farmhouse. Living Shelter then provided GRUB with an initial design which they used as the foundation for the Farmhouse plan. Having chosen FASWALL as their framing material, they brought in local designer Lisa Diane of Lucid9Design to work on the final plans. Lisa collaborated with GRUBs contractor, the Farmhouse Committee, and engineers from Harriott Smith Valentine and Mc2 Engineering throughout the project. GRUB chose a site where an old building was already standing. The choice to use a previously used site kept the project from impacting either a virgin site or potential cultivable space on our limited property.
Cost / Benefit Analysis
As far as costs, they are 5% to 10% more to frame your walls with Faswall wallforms than building walls with conventional lumber, plywood, fiberglass or foam insulation, fasteners, sealants, and wall bracing. This added investment is easily paid back in virtually no maintenance costs and lower energy bills. Other ‘paybacks’ include enhanced indoor air quality, a structure that can last centuries, is incredibly quiet, and is a great sustainable building item. The Faswall system has comparable installed cost to foam ICFs, SIPS, and advanced framing.
The exterior of the FASWALL walls are coated with 2 coats of traditional lime stucco. This consists of a mixture of lime putty (calcium hydroxide) and sand. Carbon dioxide in the atmosphere causes the plaster to set by transforming the calcium hydroxide into calcium carbonate (limestone). Lime has been used as a binder for at least 6000-7000 years, dating to ancient Egypt. The use of lime is more environmentally friendly than cement stucco for multiple reasons. The chemical process lime undergoes is carbon neutral and it takes less energy to produce. Lime is easier to repair and change colors over time. Lime is more breathable and regulates moisture more readily.
These traditional recipes were mixed by Joseph Becker of ION Ecobuilding. Interior wall finish on several of the first floor exterior walls is a pure earthen plaster, consisting of local clay, sand and chopped straw. The plaster “keys into” the FASWALL blocks due to their open texture. The clay used is as local as it gets. It came out of the ground right next to the GRuB Farmhouse (from the holes for the posts holding up the porch roof). Clay is one of the most ecological and ancient building materials. It has been used all over the world for thousands of years as the original binder (preceding lime, gypsum, and cement). Over 40 people helped smear the earthen plaster on the walls over 3 day volunteer work party called the Olympia Village Building Convergence. Finishing work was done with the help of GRuB’s Youth Crew.
|Garden Raised Bounty (GRuB)||http://www.goodgrub.org
|Polar Bear Construction||http://www.polarbearconstruction.com/GRuB_home.html
|Lucid 9 Design||http://www.lucid9design.com/07grub/grub.php
|Faswall System Information||http://faswall.com/
|Cyclic Behavior of Screen Grid Insulated Concrete Form Components
||Masters Thesis by Carl Scott Werner
|Owner: Kim Gaffi & Blu Peetz, Co-Directors Garden Raised Bounty (GRUB) (360) 753-5522||Builder: Barrett Burr Polar Bear Construction (360) 866-1456||Designer: Elizabeth Diane Lucid 9 Design (360) 789-2526|
|Subcontractor: Joseph Becker Ion EcoBuilding (360) 402-2249|