Course Information: ARCH 2614-5614
Department of Architecture, Cornell University

ARCH 2614-5614 Building Technology I: Materials & Methods

Fall 2020

Jonathan Ochshorn

Assignment 8: Low-slope roof plan showing drainage

Issued Nov. 17, 2021
Due Dec. 1, 2021 (upload PDF to canvas before class; grace period for submission without penalty extended to Dec. 9, 2021)

Introduction

aerial view of Milstein Hall, Cornell
image source

There is not much slope for roof drainage on Milstein Hall, probably because of height constraints imposed by its intersection with Sibley Hall. It's possible that this lack of adequate slope contributed to problems with leakage. Providing sloped surfaces and drainage for nominally horizontal planes is a constant struggle for architects and landscape designers, but it is something that must be done: see the Piazza del Campo in Siena (Creative Commons source) for an example of turning this requirement into memorable forms of expression:

aerial view of Siena Piazza del Campo

More commonly, nominally-flat surfaces, whether roofs or other outdoor spaces, are organized with a geometry of low-slope inverted pyramids converging on drains, as in this outdoor plaza at the Physical Sciences Building at Cornell University (photo by J. Ochshorn, Nov. 2021):

drainage patterns at the Physical Sciences Building at Cornell University

You might also want to review this Milstein Hall video for an example of what goes wrong when the abstract desire for a horizontal outside plane comes into conflict with water's evil superpowers:

Requirements

Design and draw a schematic roof drainage plan for Milstein's green roof, with the following assumptions:

Use a minimum slope of 1/4 inch per foot.
Use only roof drains (rather than roof drains and gutters).
Place all roof drains along the primary north-south lines of structure.
Draw lines from corners of edges at highest elevations to roof drains—thereby outlining the edges of each sloping plane—and draw an arrow in each plane in a downward direction toward the roof drain. See roof plan example in the lecture notes or the part of the roof plan below marked with a yellow tone.
Label the high-point elevation as HP = 30'-0" TOS ("top of slab") and label the roof drain (R.D.) elevations based on your calculation of how much vertical distance is required to achieve a slope of 1/4" per 1'-0". Show these calculations somewhere on the page.
It is not necessary (or useful) to show the circular geometry of the plantings, but you should show the skylights!

Milstein Hall Roof Plan: Click on image to enlarge.

Format

Format the assignment on any size sheet listed in the NCS, with a border and title block following the NCS guidelines.

Draw to an "imperial" scale of 1/16" = 1'-0" (approximately equal to a metric scale of 1:200).