Wood Vs. MDF Construction Specifications by Jay Bethel, CSI, CDT, SCIP Documentation, Systems and Performance Background Surface Uniformity

TECH TIPS

Providing compete Interior Woodwork - Wood vs. MDF construction specifications By Jay Bethel, CSI, CDT, SCIP documentation, systems and performance Background surface uniformity. Wood is superior descriptions, and risk and to MDF for bendingstrength, only. AWI quality advisory services. Medium Density Fiberboard (MDF) permits MDF for opaque finished has been available for many years. woodwork for Economy, Custom, and Conspectus's Tech Tips received the MDF manufacturers have developed Premium Quality Grades. national Communications Award from products to compete with solid wood. the Construction Specifications This article will focus on standing and 1. Appearance- Wood comes in a Institute September 2011. running trim products and will variety of quality levels, often with beautiful grain suitable for clear ABSTRACT: examine some differences between finishes. MDF is a uniform color, Medium Density Fiberboard (MDF) the wood and MDF products. products are plentiful and usually a shade of brown with no grain manufacturers are constantly Plywood panels were developed as a and a smooth exterior, although developing adaptations to current way to economize by using less embossed finishes are available. building trends. This article compares desirable wood remnants (referred to solid wood standing and running trim 2. Surfaces- Wood will have natural to similar products made of MDF, and as "residual" wood). The family of characteristics such as knots and explores the implications for using panel products including, both materials. particleboard and oriented strand pitch pockets that make consistent board (OSB) were invented to further finishing difficult, and can have open FILING: the economy realized by plywoods. coarse grain that telegraphs through UniFormat™ Eventually, MDF joined the fold as an finishes. MDF does not have these C1090 - Interior Specialties even more efficient product. To make characteristics and offers a uniform, C2010 - Wall Finishes smooth surface. C2020 - Interior Fabrications MDF, wood chips are reduced to C2040 - Stair Finishes cellulose fibers that are combined C2050 - Ceiling Finishes with resins and wax, and then molded 3. Exposure to Water- Both wood and together under heat and pressure. MDF are susceptible to damage from MasterFormat® water, particularly chronic contact with 06 20 00 - Finish Carpentry water. MDF tends to deteriorate faster 06 40 00 - Architectural Woodwork Moldings, such as baseboards, crown, casings, and other specialties, when in contact with water. Wood KEYWORDS: have been wood, traditionally. Exotic tends to warp, cup, and change Agrifiber, hardwood, LEED, MDF, wood species and more common dimension. medium density fiberboard, oriented strand board, OSB, panels, hardwoods such as mahogany, particleboard, plywood, recycled, maple, oak, walnut, and cherry resin, standing and running trim, urea maintain the top of the quality chart formaldehyde, wood for transparent finished woodwork. Many of the paint-grade wood REFERENCES: products have MDF competition. ANSI A208.2 Medium Density Fiberboard for Interior Applications AWI Architectural Woodwork Wood vs. MDF Standards Under the AWI Architectural Woodwork Standards, MDF is considered a panel product not lumber. AWI rates MDF superior to wood for flatness, visual edge, and TECH TIPS

4. Humidity- Wood is highly and recovered wood fiber as raw craftsmanship, these trim materials susceptible to changes in humidity, materials, MDF products are can replace solid wood so the general MDF less so. It is best to keep wood generally less expensive than solid public will be unaware of the in an environment maintained wood products. substitute material. between 30% and 65% relative humidity (10% to 15% moisture 8. Jobsite Use- Both wood and MDF Conclusion content in the wood) to minimize the products must be allowed to acclimate to the project site conditions prior to dimensional changes. At RH greater Wood will not be replaced by MDF installation. than 65% dimensional changes for type materials because wood has a wood are significantly more than for value, texture, and appeal that cannot MDF. Remember these factors: MDF Variations and be completely recreated by man-  MDF changes dimensions equally Properties made materials. Many common uses across the width and along the of wood do pose some questions length. Manufacturers of MDF products are about conservation and sustainability, constantly developing variations and such as the depletion of rainforests,  Wood dimensions change across improvements to meet industry the lifespan of many wood products, the grain not along the length. requirements. MDF is made from and the "carbon footprint" of  Plain (tangential) sawn lumber will cellulosic fibers which include different construction projects. change twice as much as quarter types of wood materials, and (radial) sawn lumber. agrifibers such as wheat, barley, and While MDF is not a perfect substitute for wood and is not the only choice as  Wood changes vary by species. other cereal straw (also called bagasse). a replacement for wood, MDF is a 5. Sustainability- Most wood products viable, economical replacement in are harvested from well managed, A variety of different resin many applications. In addition, with renewable sources (FSC Certified formulations are used resulting in a the constant societal pressure to Wood). Sawing lumber from trees variety of products ranging from develop increasingly sustainable generates waste. MDF makes use of heavy, plywood-type panels, to light materials, MDF is well represented in entire trees. MDF can be made from weight, eco-friendly materials. the overall selection of materials that 100% recovered wood fiber. contribute to sustainable design, Manufacturers produce MDF products resource conservation, and 6. Workability- There is less waste with no added urea formaldehyde, construction affordability. when using MDF as opposed to wood, independently certified 100% pre- especially for standing and running consumer recycled content, FSC trim. Lengths of wood will be certification, and Class A fire retardant Add Your Comments selectively reduced to remove rating. MDF products are sustainable We invite your comments. Visit our blog imperfections before installation. MDF and contribute to the following LEED and add your comments. moldings have no such defects and Credits: are 100% usable. Like it? Share it! MDF is easily milled to produce clean  MR 4 Recycled Content Tweet or Email your friends surfaces and many products come  MR 7 Certified Wood pre-primed, with a surface  EQ 4.4 Low Emitting Materials- composition that is compatible with The information contained in this document Composite Wood high quality finishing techniques. MDF is offered for educational purposes, only, can be finished with a variety of MDF standing and running trim is and not as technical advice suitable for any paints, including acrylics and alkyds. available with printed laminate films particular project or specific condition. Catalyzed lacquers and varnishes are applied to the exposed surface to Technical consulting is unique to the facts incompatible with the adhesives in the simulate a transparent wood finish. of a particular condition, and Conspectus MDF material. With careful detailing and installation recommends that a specialist be consulted to determine solutions for each specific 7. Costs- Due to the use of "scrap" condition.