NFBA’s market research proved that the two primary obstacles to post-frame industry growth are stereotypes about the external appearance of post-frame buildings, and concerns about using treated wood as a foundation system.
To help correct widespread misconceptions, NFBA is developing a special web site, advertising materials and a hard-bound book that explains clearly the various options available for post-frame. Below are edited excerpts from the new book, which is titled “The Post-Frame Advantage.” Product brand names, URLs and details for some systems listed below will not be included in the book.
Part I: Post-Frame Foundation Options
Most post-frame buildings utilize a permanent wood foundation comprised of pressure-treated posts or laminated columns that are embedded directly into the ground. Post-frame buildings may also be bolted onto a reinforced concrete slab or a traditional cast-in-place concrete or masonry block foundation.
Post-frame buildings may also utilize innovative products that provide alternatives to placing wood directly in ground contact. Post-frame buildings may utilize enhanced wood treatment techniques and wood protection products developed specifically for post-frame buildings, such as plastic sleeves or boots, and concrete posts or piers.
Whether you choose the time-tested and proven method of embedding treated wood directly in the soil or you select a concrete masonry wall or one of the other products developed specifically for post-frame foundation use, you can be confident that a post-frame building will provide a permanent building solution.
Innovative Post-Frame Foundation Products
In addition to the traditional, preservative-treated wood post foundation, there are a variety of products that offer post-frame foundation options.
Pre-cast reinforced concrete columns designed specifically for post-frame construction utilize a bracket that extends 18 inches above grade to which a solid-sawn post or laminated column is affixed.
• A standard non-treated wood column can be bolted into the “U” shaped connection bracket, eliminating the need for treated wood.
• Reinforced concrete columns are made of 10,000 p.s.i. pre-cast concrete with built-in corrosion and freeze/thaw protection. This special blend ensures superior durability to the standard 3,000-4,000 p.s.i. concrete typically found in most building foundations.
• With an innovative uplift system, no ready-mix concrete is needed for installation. This allows the builder to combine the efficiency of post-frame construction with the durability of concrete.
• Pre-cast reinforced concrete columns maintain their value and give the building owner peace of mind.
(Pre-cast reinforced concrete columns are provided by NFBA member company Perma-Column, Inc. www.permacolumn.com)
Poured-in-place concrete piers use a pier bracket placed over a hole filled with concrete. Once the concrete sets, the post-frame is bolted onto the brackets.
• Poured-in-place concrete pier systems utilize a bracket that has an engineer’s stamp, assuring code compliance.
• A commercial bracket that also carries an engineer’s stamp certifies that it can carry the moments and the forces of a 6 x 8” laminated column.
• Concrete piers provide a neat, clean look on the inside, without columns being spliced and roof purlins run continuous end-to-end.
• Piers are on grade, which allows prefabricated walls installed on the ground.
• Builders can put trusses on end walls with door headers pre-installed, which saves labor.
(Poured-in-place concrete piers are provided by NFBA member company Concrete Pier Systems)
HDPE plastic barrier wood protection systems for enhanced protection of copper-based chemical-treated wood posts and laminated columns
• A plastic sleeve with an enclosed bottom covers the embedded portion of posts or columns.
• Offers a low cost, simple to use and beneficial enhancement to embedded treated wood posts.
• HDPE plastic used in the product is completely resistant to moisture, organic matter, concrete, most chemicals (including wood preservatives), animal wastes, etc.
• The sleeve is designed to fit posts cleanly while still allowing ventilation. Builders don’t have to alter construction methods or worry about fit and finish of other framing members.
• Cuts easily with snips, saw, or knife.
• Consultation, research and construction confirm the product’s performance.
• Also available to cover post-frame skirtboards with a barrier between corrosive treated woods and metal trims and siding.
(HDPE plastic barrier wood protection systems are provided by NFBA member company Plasti-Sleeve, www.plasti-sleeve.com)
Blow-molded plastic barrier system for enhanced protection of copper-based chemical-treated wood posts or laminated columns
• Provides moisture and insect protection from footer to above finished floor grade.
• Molded to provide post uplift protection.
• Allows for safe concrete post encasement.
• Prevents chemical leaching from treated posts into soil or ground water.
• Post venting system allows the post to breathe.
• Simple slide-on installation and framing-friendly design.
• Strong, yet pliable and lightweight
• Easy to ship, store and handle
• Attractive coloring and wood grain texture.
(Injection-molded plastic barrier systems are provided by NFBA member company Post Protector, www.postprotector.com)
Polyethylene post sleeve and footing forms for enhanced protection of copper-based chemical-treated wood posts or laminated columns enclose the post and create a foundation-strength base.
• Creates a foundation-strength base for post-frame buildings
• Provides uplift protection and a way to pour footings
• Finished post and footing is fully enclosed and protected from pests and moisture for the lifetime of the building
An Asphalt and Polyethylene Based Barrier Wrap Protection System that is termite tested, laboratory proven, ICC-ES building code compliant and AWPA standardized.
• The surface of the wood is coated with asphalt, and a heavy-duty polyethylene shrink film is factory applied to offer a durable protective outer layer.
• The barrier protection system retains chemical penetration and enhances the service life of wooden posts treated with all types of water-borne wood preservatives.
• Provides a technically viable and building code compliant alternative to chemically-treated lumber in weather-protected applications such as post frame construction.
• An uplift restraint notch is pre-applied to the posts prior to the application of the barrier system.
• May be used on solid-sawn, nail-lam and glue-laminated posts.
(Asphalt and Polyethylene-based Barrier Wrap Protection Systems are provided by NFBA member company PostSaver, USA, www.postsaverusa.com.)
Case Study: Injection-molded plastic barrier system
Shown is an artist’s depiction and photo of work under way on a state-of-the-art, $2 million, 15,000 square foot commercial facility for Talbot County Soil Conservation Service in Easton, Md. The building consists of six office suites and is occupied by state and federal agencies.
“For this and many projects, the plastic barrier system is a tool that promotes consumer confidence,” says builder Joe Kramer. “It’s a sensible, effective and affordable solution to address post longevity concerns. We believe plastic barrier systems to be the perfect complement to post-frame construction.”
Treated Wood for Post-Frame
Many post-frame buildings use treated wood embedded directly in the ground to form a permanent wood foundation. Post-frame buildings that use the proper treated wood products suitable for post-frame foundations have a long history of success.
Many people think all treated wood is the same, and are not aware there are many types of wood commodities available that have been treated in various ways to meet specific purposes. Because decks and playground equipment are not generally considered crucial building structural elements, treated wood for those applications is not produced to the same specifications as for post-frame buildings. Properly treated and installed posts will ensure a post-frame building will last.
The USDA Forest Products Laboratory has conducted long-term tests in the harshest environments found within the continental U.S. Chromated Copper Arsenate (CCA) type II at retention level .26 pcf treated test stakes have showed no signs of failure since their installation in 1949.* Modern post-frame buildings typically use the newer, improved formula CCA type III at retention level .60 pcf.
Wood treatment is governed by standards set by the American Wood Protection Association (AWPA). Treated wood for post-frame skirtboards should be treated to AWPA use classification standard UC4A; a larger amount of treatment chemical is forced more deeply into the wood for UC4A than is for deck, playground and other common uses.
Laminated columns and solid-sawn posts should be treated to at least UC4B, or a minimum of .60 pcf CCA. If you feel an extra level of wood protection is needed, you may order wood treated to UC4C, or .80 pcf CCA. Kiln Drying After Treatment (KDAT) also improves the performance of treated wood products.
Part II: Roofing and Exterior Cladding
Imagine a building marked by large wall cavities that can easily accommodate a substantial amount of thermal insulation. Furthermore, imagine that structure may be covered with almost any type of external and internal finishes. It could have wood siding, metal siding, vinyl siding, stucco, brick, or stone masonry façade. It could have any type of composite shingle, metal, or commercial roofing envelope.
It could serve almost any purpose, from commercial to residential, retail to academic, public to industrial. It could be a church with a steeple and cathedral ceilings. It could be a library, a fire station, or a schoolhouse. It could be a strip mall or convenience store. Perhaps it looks like a warehouse, a manufacturing facility, an airplane hangar, or even a financial institution. But maybe it looks instead like a nice house, a suburban garage, a spacious barn, a country club, or an office building. It could even be anywhere from one to three stories tall.
Most people who are not familiar with modern construction methods might imagine different types of buildings to fit the above descriptions. They may conjure up images of their old concrete-block school, their brick-and-mortar church, their grandmother’s stucco home, or their local bank’s limestone entryway. But they might be surprised to know that a savvy builder could easily imagine that all of them could be most quickly and economically erected as post-frame buildings.
Across the country and right next door, the many “faces” of post-frame are everywhere. From simple and efficient to eye-catching and elaborate, post-frame versatility is limited only by your imagination.
Because so many types of materials may be used on the facade, people often may not realize it when they are looking at a post-frame building. According to Tim Royer, P.E., “Architecturally, any structure you see driving down the road could be a post-frame building, because the finishes would not look any different from another style of building.” Today, it makes little difference whether the building purchaser favors the aesthetics of wood siding, brick or stucco; virtually any look is possible with post-frame.
Professional engineer Ron Sutton agrees.
“We regularly design and build churches and other buildings using a wide variety of building materials, including wood, brick, stone, and many other building products. The features of post-frame design allow us to incorporate flexibility so we may employ architectural enhancements of all kinds to achieve the desired appearance.”
Post-frame roof coverings can also achieve almost any look. Roofing materials such as composite or cedar shake single, slate, tile, metal and other membranes may be used. Any roof pitch may be selected, and practically “flat” low-slope roof decks can be installed upon which a watertight system may be added.
* Crawford, D.M.; Woodward, B. M.; Hatfield, C. A., comps. Comparison of wood preservatives in stake tests. 2000 Progress Report. Res. Note FPL-RN-02. Madison, WI: U.S. Department of Agriculture, Forest Service, Forest Products Laboratory, P. 121.