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151 Carpentry July–August 2012 The main design feature of the Mission of Hope School is a pair of staircases that begin at the ground floor near the central front entry, ascend away from each other to access the perimeter galleries along the first floor, and then turn back to rise to the second floor where they come together on a generous landing at the main entrance to the church. Stairs that begin at the same place, diverge, and then come back together are called sweetheart stairs. Ours are wide and grand to accommodate hundreds of people climbing to church services. They will also make a great circuit for children playing tag. We’re starting to build the stairs. First we need to establish key dimensions and erect very specific wooden formwork. It’s as close to finish carpentry as this project will require. Later we’ll install the rebar and pour the stairs in concrete. Like all first days of new work, progress is slow and miscommunication rampant. It takes us three hours to determine the stairs’ beginning and end points. We mark the top of the future ground floor (the ground-floor slab will be poured after we install underground electric and plumbing connections). We dangle a two-by-four from the first floor to measure the vertical distance between floors. I would prefer to measure from the ground up, but I learned that Haitians have a predisposition for suspending building elements in space when they determined the initial square of the building by floating a framing square. Perhaps they don’t trust the solidity of the ground; perhaps they like the challenge 152 Architecture by Moonlight of establishing equilibrium in open air; or perhaps they just don’t like to crouch down. In this case our method, however haphazard yields a result exact enough; the total height is 10 feet, 3-3/4 inches , only a quarter inch off our 10 feet, 4 inch design dimension. Two factors determine the comfort level of climbing stairs. The first is the relationship between the vertical face of each step, the riser, and the horizontal plane where we place our foot, the tread. The dimension of these two planes must be within a proportional range; the steeper the rise, the shallower the tread. Monumental stairs have long treads, as much as fourteen inches, with risers as little as five inches. Service stairs can have risers as tall as eight or nine inches, but the treads must be correspondingly narrow for comfort. The rule of thumb architects use is that rise times tread equals 75+/-. Seven in eleven is the most common stair ratio in the United States, and exterior stairs should never be steeper. Our vertical dimensions divide evenly into eighteen risers, each 6- 7/8 inches high. Therefore we will need seventeen treads, each 11 inches wide. The second factor in stair comfort is that all risers must be exactly the same dimension. The human gait can differentiate changes in riser height as little as 1/8 inch. Uneven stairs force us to look down and concentrate on our feet, rather than allowing us to ascend with grace and certainty. Riser heights in Haiti are notoriously erratic, and if Renee has made one firm demand on this project, it is that she wants perfect stairs. I explain to the carpenters that I want to create a reverse formwork to outline where the stairs meet the wall. This goes over easier than I expect, and within a few minutes, bits of 11 inch by 6-7/8 inch plywood cascade diagonally along the block wall. Now I have a problem. There is nothing inherently wrong with what they are doing, but the opportunity for small mistakes accumulates with so many small pieces of wood. If each plywood rectangle is only 1/16 inch off, we will generate a one-inch discrepancy over the entire staircase. I fetch Renee, whom I rely on for subtle negotiation . I tell the workers their plywood rectangles are not wrong, but they might lead to cumulative error; whereas, if we cut multiple stair teeth out of single piece of plywood, we can be more accurate. Words like cumulative do not exist in Creole, but Renee is a master at converting my vocabulary to local vernacular. She tells them 153 Carpentry what they have done is good, but if we use larger pieces we will be plus exactement. That phrase goes over well. We get a...

ISBN
9780826273321
Related ISBN
9780826220394
MARC Record
OCLC
900223848
Pages
224
Launched on MUSE
2015-01-15
Language
English
Open Access
No