Covered Bridges: How to Build and Rebuild Them

covered bridges how to build and rebuild them

“This manual is intended to provide comprehensive support to those involved with maintaining, assessing, strengthening, or rehabilitating covered bridges, especially heavy timber truss bridges. At one time, the United States reportedly had 14,000 of these unique bridges dotting the countryside over a surprisingly large area. Now, fewer than 900 of the historic structures survive.

Timber bridges initially were built without coverings and failed in just a few years because of rot and deterioration, because chemical wood preservatives were not available or used. Builders familiar with the construction of houses, barns, and large community structures naturally added siding and roofs to help protect the bridge. They understood that the covering would soon pay for itself.

They believed that regular maintenance and occasional replacement of the light covering was far easier and cheaper than building an entirely new bridge. North American covered bridges still serve after nearly 200 years, due in part to the continued soundness of the trusses, which was possible only with these protective coverings.”

Covered Bridge Manual“, 327 pages, US Department of Transportation, 2005. Via Arquitectura y madera. Previously: wooden bridges / wooden pipelines. Picture by Rainer Ebert.

Social Conflict and the Age of Scarcity

Riots in greece “In an age of abundance, the easiest way to deal with social conflict is to buy off the disaffected. That’s how industrial societies over the last century came to provide welfare for the poor, mortgage guarantees and college grants for the middle class, subsidies for farmers, tax breaks for businesses – name a group that’s had enough political savvy to organize and raise a ruckus, and you can just as quickly name the arrangements by which they were paid off to minimize the risk of disruptions to the system. That was politically feasible in an expanding economy; even when the shares of the existing pie were grossly unequal, the fact that everyone could have at least a little more each year made those with smaller slices willing to work with the system in order to get their cut.

In an age of scarcity, that easy option no longer exists, and social conflicts heat up rapidly. That’s the unmentioned subtext for much of what’s going on in politics on both sides of the Atlantic just now. The middle class, who shrugged and turned its collective back when the working classes of Europe and America were thrown to the sharks thirty years ago, are now discovering to their horror that they’re next on the list, as the rentier class – the relatively privileged fraction of industrial society that makes its living from investments rather than salaries – struggles to maintain its prosperity at everyone else’s expense. The gutting of social safety nets, the slashing of salaries and benefits, and the impoverishment of millions of previously affluent people are part of that process, and lead to a rising spiral of social conflict that may well push a good many nations into crisis or collapse.”

Read more: How not to play the game. Picture: Oneiros.

Portraits of Farm Animals

Portrets of farm animals

Portraits of farm animals by Rob MacInnis. Via The Brook (“We are an international animal welfare organisation dedicated to improving the lives of working horses, donkeys and mules in some of the world’s poorest communities”).

Talk at LIFT Conference: Be Radical

Lift I will give a talk at the LIFT Conference in Marseille, France, July 8. “Lift France 11 is a three-day conference about current and emerging use of digital technologies and their effects on innovation, societal and economic transformation. Under the slogan “Be Radical!”, Lift France will focus on disruption: when (high- or low-)tech contributes to redefining a market’s terms of reference, a whole industry, a share of social life, etc. Participants come to better understand the challenges and opportunities presented by digital technologies, to meet the people who drive these innovations, and to share their own insights”. More info here.

Fences of Fruit Trees

fences of fruit trees

“Almost anyone who has a backyard or garden would do well to plant fruit trees for the years ahead. Most fruit trees, though, take more years to mature than most of us have to prepare, and take up more space than most of us have in cities or suburbs. Luckily, only a few centuries ago master gardeners developed a way to cultivate fruit in narrow spaces – one that yields more fruit, more quickly, and with a longer growing season.

Espalier is a method of growing a dwarf fruit tree along a wall or fence, binding it for support, and bending the branches to follow certain lines, as Japanese artists do with bonsai trees. Most gardeners started espaliers with a “maiden,” a one-year-old sapling that had not yet forked, and tied it to a staff of wood to keep it straight. Then they tied the desired branches to the fence or wall as they emerged, bending and pruning aggressively as the tree grew.

With the tree’s natural growth concentrated into only two dimensions, it creates many spurs looking for a chance to spread, creating more flowers and fruit than their conventional counterparts, and earlier in the trees’ life. The fruit can be picked casually while standing or sitting, with no need for the ladders or devices needed to pick many other fruit trees, and no risk of injury. Growing a tree against a south-facing wall has another advantage; not only does the tree receive maximum light and heat, but the thermal mass of the wall absorbs the heat and provides shelter from the wind. In this way trees get a longer growing season, and can grow in cooler climates than they would ordinarily tolerate.”

Read more: Fences of fruit trees. Related: Irish hedgerows.

Window Orientation and Shading

window orientation and shading

“In sunny southern locations, protecting your windows from the sun is an important component of good window management. The first step is to know how the sun moves through the sky and to orient the building and place the windows in it so as to minimize direct solar admission through your windows.” Read more.

“Sustainable By Design provides a suite of shareware design tools to calculate the right dimensions and placing for your specific location, wherever you are.

  • SunAngle: our premier tool for solar angle calculations.
  • SunPosition: calculates a time series of basic solar angle data.
  • Sol Path: visualization of the path of the sun across the sky.
  • Window Overhang Design: visualization of the shade provided by a window overhang at a given time.
  • Window Overhang Annual Analysis: visualization of window overhang shading performance for an entire year.
  • Overhang Recommendations: suggested climate-specific dimensions for south-facing window overhangs
  • Light penetration: visualization of the penetration of sunlight into a room
  • Louver Shading: visualization of louvered shading system performance for an entire year.
  • Vertical Fin Shading: visualization of a vertical fin shading system performance for an entire year
  • Window Heat Gain: calculation of monthly heat gain through windows.
  • Panel Shading: visualization of the shading of rows of flat panel collectors throughout the year.”

Interesting follow-up at Treehugger.