A week before Christmas, I fell into conversation with an old Polish scrapper at the ReBuilding Exchange.  He had an epic beard (one that may have supported a small ecosystem of bacteria and woodland creatures) and a slight accent from his boyhood in Eastern Europe.  He and his brother were there to pick up pallets, which they would then strap to the roof of his biodiesel Mercedes wagon and sell.  Small -- 36" x 36" or so -- go for a dollar each, while large -- 36" x 48" -- go for a solid two-fifty.  

It seems like small cash, and it is.  You have to collect a helluva a lot of pallets to turn a profit.  But, as my Polish friend discovered, if you can drive costs down, and find an efficient pick-up route, the economics creep into the black.  By using vegetable oil in his car, he's eliminated the biggest cost, fuel.  By finding an efficient route, he's cut man-hours to the bone.  I saw him again last week, prowling my neighborhood for promising construction dumpsters.  The car was rattling within an inch of its life, throwing up a stream of french-fry scented exhaust.

A pallet recycling yard near my work, at Hoyne and Grand.

Deceptively complex, pallets have two main parts: stringers, the three long "joists"; and the slats, the half-dozen cross-pieces bridging the stringers.  The strength comes from the stringers, which are typically some kind of regionally available hardwood such as ash, oak, or hickory.  The slats are usually cheap pine, often with bark edges still visible, off-cuts from the sawmill that aren't commercially salable.  Durability comes from the hardwood and the fasteners, which range from regular nails to twist or ring-shank nails to staples.  Hardwood stringers hold fasteners well, and their untreated surfaces absorb moisture and swell the wood, making the nails even more loathe to pull out.  A typical pallet can bear about one U.S. ton (2,000 lbs), and will last between four (white wood) and 30 (pooled wood) trips in the supply chain.  

Technical drawing of a pallet, courtesy of Paltech Enterprises.  
Pallets are a fascinating by-product of our consumer-industrial complex.  As a design object, they are deceptively complex.  They try to resolve a number of opposing goals -- strong yet light, durable but cheap, disposable and re-usable, while also being standardized into a highly ordered, mechanized global supply chain.  They have to tile effectively into various spaces, from box trucks to shipping containers, yet they aren't always square.  Standard sizes start at 36" x 36", then 42" x 42", and then double pallets, at 48" x 40".  A standard shipping container's interior dimensions, however, fail to neatly resolve  into pallet-sized tiles.  At 479-3/4" x 95-1/4" (interior dimensions), a 40' shipping container will have about 35" left over in the long dimension and 23-1/4" leftover in the short dimension when tiled with 36" pallets, which adds up to about 100 square feet of wasted space in a 320 square foot container, or nearly a third of the available floorspace.  I assume some of this discrepancy has to do with interior dimensions of the container as opposed to exterior dimensions, and some of it is an allowance for loads that overhang the footprint of the pallet.  

Pallet size leads to an interesting conversation about the dimensions of our world.  Unlike standardized building materials and shipping containers, pallets are not built on a 24" module, bricking into neat 4' x 8' spaces.  It seems to be an unusual gap in the relentless standardization of our world, from stud lumber to the size of parking spaces.   For instance, a standard interior doorway is 30", while an ADA-accessible doorway is 36".  A pallet, therefore, cannot navigate even a handicap-accessible door opening in a building, meaning pallets are meant only for industrial or commercial applications.  More practically, and I have experienced this in several jobs of mine, it means the last hundred feet of any journey of any object must occur by hand.  Pallets also govern, or are governed by, the size of forklift forks.  Their dimensions seem arbitrary, but, then again, forklifts are versatile machines, designed to move all sorts of dissimilar materials.  

The first forklift-esque machines began appearing in America around 1909.  Spurred by both the development of the railroad and World War I, designs for load-bearing carts of various kinds proliferated.  Most were still human-powered, with ball-bearing wheels, allowing a single man to shift around 1,500 pounds.  The addition of batteries and electric motors doubled and even tripled that weight limit.  However, the idea of a forklift -- a hydraulically motivated machine with two-pronged lifting device on the front -- took much longer to develop, as hydraulic technology is tricky to engineer and build.  The first fork-type machines appeared after the war, designed to lift skids, basically one-faced pallets with a pair of stringers.  

However, skids are quite weak, susceptible to deflection because there is no bottom to keep the stringers from kicking out.   Around 1930, the first modern pallets began to appear, with three stringers and slats on both the top and the bottom.  Gaps in the slats on the bottom still allowed for the use of more primitive, human-powered pallet jacks that rely on small levering wheels under the front tip of the forks.  This allowed for much greater weight-bearing capacity and the use of cheaper, weaker wood, as the overall design was inherently stronger.  These new pallets and forklifts also changed the face of warehousing and shipping, as they allowed loads to be stacked and manipulated much easier.  Some degree of standardization, sized to boxcars and the weight of ammunition shipments, was introduced by the Bureau of Ordnance during World War II.  While they settled on 48" x 48" pallets, which seems logical, various branches of the military and commercial concerns splintered on the size issue, leading to the randomized selection we see today -- the original VHS vs. BetaMax.  

World War II pallets.  
Now, pallets are one of the most prevalent byproducts of our consumer-industrial complex.  They litter back alleys, loading docks, and shipyards.  Hard to take apart, warped, twisted, wet, and studded with nails, they don't seem like the best candidates for re-use.  On the other hand, they are the cheapest source of hardwood going.  I have used pallet-sourced wood for lots of projects, usually when I needed small, dense pieces for something like feet or legs on a table or small cabinet.  

This trash cabinet rehab I did recently uses pallet wood for feet, solid white oak.
Pallets have been turned into to a wide variety of design objects, as folks have tried to capitalize on the free or cheap lumber.  Furniture is an obvious use.  The gridded nature of pallets also makes for an interesting vertical garden.  As interior design, pallets can be used to define space, serve as stairs, and be used as built-in desks.  Other folks prefer jokes.  Conceptual artists have taken their liberties, repurposing bits of plastic and cardboard pallet components into masks.  Pallets, as I learned at Arcosanti, also make a mean compost heap or chicken coop.  

Pallet votive holders, one of the RX Made products at ReBuilding Exchange.  The streaky, beautifully-grained wood is probably ash, a high-quality hardwood.
People have also been thinking bigger than furniture, building tiny houses out of pallets.  As units, they are already structural -- the stringers can be screwed together to make panelized walls.  I'd be somewhat worried about the long spans of 3' pallets sistered together, but most of these structures seem small enough to mitigate this issue.  The PalletHaus seems to be the most beautiful example that I have found, as they have come up with several sleek, modern forms that don't fall into easy "scrap" pigeonholes.  

PalletHaus at the Venice Bienalle.  They have resolved structural issues by making double-thickness walls, staggering the joints. I like the clean aesthetic, which acknowledges the material without falling prey to it.  Photo via InHabitat.
Another gorgeous pallet project, falling somewhere between architecture and sculpture, is the Palletten Pavilion (Cave) by Matthias Loebermann.  He has found a way to create an organic form out of platonic shapes, flowing the squares and rectangles into a windswept pile.

The Palletten Pavilion (Cave).
The folks at DesignBuildBLUFF put together a lovely home for a Navajo family out of rammed earth and pallets in Utah.  This isn't their first house to utilize pallets; here they are used as a rain screen, but in other homes, they used pallets as roof support and interior walls as well.  

Photo via InHabitat.
I would love to build a pallet house.  I think they could be turned into small, strong SIPs -- insulated by stuffing them with plastic grocery bags, or chopped straw, or shredded newspaper.  Made of hardwood, they are strong for their size and rot-resistant.  Already standardized, it would be simple to design around the given units and create a pallet-only house, strong, cheap, and sustainable.  Even if you had to buy the pallets, they trade at less than $5 each, so amassing enough for a small structure wouldn't take a lot of dough.  Who knows -- 20K Pallet?  

There is a sense of pallet fatigue -- much as with shipping containers, wine corks, and milk crates, they've become a ubiquitous design trend.  Some of this exhaustion has to do with hacky or cheap adaptations of pallets, making crummy lawn furniture or yet another Adirondack chair.  I see pallets as raw material -- the issue with all of these trends that appear, crest, and dissipate is that folks aren't fundamentally transforming anything, either conceptually or physically.  Pallets are a good source of inexpensive, quality hardwood in an urban environment.  They also have some interesting structural and visual qualities, allowing them to be used in a complete state.  

I'll probably still be mining alleys for pallets long after the blogosphere has gotten over them.  Perhaps my retirement will be funded by trolling alleys in my biodiesel Benz, pallets strapped to the roof, hustling hardwood . . .