Residential Construction and Materials Use in the 21 st Century Doing more with less, or, as the Forest Products Lab put it, “Extending the Resource”

The New Revolution in Residential Construction The most significant changes in American residential construction since Augustine Taylor developed light framing in 1833

What inspired light framing? Local shortages of timber supplies Need for housing to accommodate a growing population A shortage of skilled carpenters, especially on the frontier Has been modified in a number of ways since but is still the way we build houses

We are faced with similar challenges at the start of the 21 st century Timber supply issues –12 billion BF per year of timber from public land off the market –Second growth (small & poorer quality) Growing population (32 million growth between 1990 and 2000) Demographics of an aging population affects labor in the construction industry

U.S. Population:

How to meet the challenge Use less wood to achieve the same results Use underutilized wood supplies –Different species –Small diameter logs –Low quality/poor form logs Create efficiencies in construction –Save time and labor through modular construction and prefabrication

“Déjà vu all over again” Bernhard Fernow’s “timber physics” research – U.S. Forest Products Laboratory established in Madison, WI: 1910 Wood science academic programs: –1 st program: 1929 –12 new programs: (WVU: 1947)

Engineered Wood Products: The next generation of wood-based composites

Principles of Wood-Based Composites Recombine small pieces of wood into larger products using adhesives Design the product to achieve desired properties –“Furnish” geometry –Product geometry –Grain orientation of components –Processing (resin and pressing variables)

Furnish Geometry: the Raw Materials Lumber: 2 X 4s, 2 X 6s, etc. Veneer: a thin slice of wood taken from a log Chips, particles, flakes, and strands: Small particles of wood – some with specifically designed geometries Fibers: Single cells or clusters of cells (pulp)

Raw Material Requirements Lumber: Moderate diameter (8” – 12” minimum) and relatively straight Veneer: Large diameter (8-9” practical minimum) and straight Chips, particles, flakes, and strands: 4” diameter minimum, straightness not a factor, some species limitations Fibers: Same as above

Product Geometry “Timbers”: Large structural members – beams and columns, arches, etc. “Lumber”: Light framing for residential construction Panels: Thin sheets of material – typically, but not always, 4’ X 8’

Grain Orientation Grain describes the principal direction of the majority of cells in wood

Grain Orientation Wood is approximately 10 times stronger parallel to the grain Wood tends to shrink and swell significantly with moisture content changes perpendicular to the grain, and a negligible amount parallel to the grain

Grain Orientation Grain direction of all composite components may be arranged either parallel to each other or perpendicular –Parallel: the product will be very strong in one direction and will not tend to shrink and swell in that direction (timbers and lumber) –Perpendicular: the product will have uniform strength and greater dimensional stability (panels)

Resin & Pressing Variables Resin –Water resistant for outdoor exposure –Non-water resistant for indoor exposure Pressing –Temperature –Pressure

Show & Tell

Glulam lumber (2 X 4, 2 X 6, 2 X 8) Uses lumber (2 X 4, 2 X 6, 2 X 8) Can make very large structural timbers : parallel Grain orientation: parallel : indoor or outdoor Adhesive: indoor or outdoor Pressing variables: cold curing in clamps

Glulam Older generation product Design flexibility Local Use –3 rd Floor lobby –WVU Natatorium –Rail Trail Bridge at Marilla Park –Christian & Missionary Alliance Church

Trusses Older generation product lumber (mostly 2 X 4s) Uses lumber (mostly 2 X 4s) Prefabricated Excellent structural properties No adhesive – metal fasteners

Trusses Roof and floor trusses Span is limited to approximately 16 – 20 feet Longer spans require wider lumber Fast erection on the job site

Plywood Veneer Glued into standard 4’ X 8’ or 4’ X 12’ panels Thickness varies Grain of each “ply” is perpendicular to the next ply Improved strength and dimensional stability

Plywood Replaced solid lumber for subfloor, siding, and sheathing Requires less labor to install Reduces processing waste from approx % for lumber to % Requires large diameter, straight logs of a suitable species

Oriented Strandboard (OSB) Strands (approx. 1/32” X 1-2” X 3-4”) Glued into standard 4’ X 8’ or 4’ X 12’ panels Thickness varies Strands are layered to simulate plywood’s properties

Oriented Strandboard (OSB) Replacing plywood for subfloor and sheathing Reduces processing waste from approx % for plywood to a negligible amount Can use small diameter, poorly formed logs of more species than plywood – including logging residue

Laminated Veneer Lumber (LVL) Veneer Glued into panels of unlimited length and sawed to a specified width Thickness varies Plies are layered with the grain parallel

Laminated Veneer Lumber (LVL) Replacing solid lumber for columns, beams, and headers Stronger and straighter than solid wood It’s ability to carry greater load can reduce the number of pieces needed in a building system

Parallel Strand Lumber (PSL) Low quality veneer strips Pressed into large structural components through an extrusion process Size may vary Parallel grain

Parallel Strand Lumber (PSL) May be used for columns, beams, and headers Technology may be ahead of marketing TrusJoist in Buckhannon, WV – integrated with LVL manufacture

Engineered Wood I-Joists Flanges (top and bottom): lumber or LVL Web (middle): plywood or OSB Length limited only by shipping Very strong and straight

Engineered Wood I-Joists Replacing solid lumber for joists (beams) Can reduce consumption of wood in a floor system by 50% Fills 40% of the residential floor framing market

Structural Insulated Panels (SIPs)

“Sandwich” of OSB panels and styrofoam insulation May contain framing lumber, wiring, plumbing Very easy and fast to construct a house

Hybrid Composites Wood-Plastic Composites (WPCs) –Deck boards, window frames and sashes, siding –Still leave a lot to be desired but research is ongoing

Hybrid Composites Wood – Agricultural Residue Panels –Panels on the market –Still in the early stages of development Nanotechnology

Summary Things are changing rapidly Driven by changing resources, demographics, regulation, and technology The constant is human ingenuity The limits of technological growth are not in sight.