Opportunity Definition feedback[edit source]
Thanks for the start on the opportunity definition. It is quite sparse and needs more information. Here are some starting notes:
- The background needs more information. When was the Yurt built? When was the roof put on? What semester is this? A photo would really help.
- Why recycled materials only?
- Please add links to your user names.
--Lonny 19:05, 7 February 2013 (PST)
shingling geometry[edit source]
The shingling pattern you've chosen is not waterproof. Shingling with rigid materials is common in the form of slate roofs. With slate you need to use a "headlap", usually of 2"-4". Your shingling pattern has no headlap, and is in many places directing water from one shingle laterally (horizontally) underneath the adjacent shingle, and then vertically behind the next shingle down. Your roofing paper is the water barrier at that point.
There are several ways of reusing tin cans to make shingles. The most material efficient is to make shingles with standing seams on the left and right edges. That eliminates the need for headlap, and instead 1"-2" overlap is all that's necessary (standing seam prevents water from moving horizonally). I'm experimenting now with this, and with also just flat shingling (no seams) but a reduced headlap of 1"-2". This could be problematic in snowy conditions, but in rain, water shouldn't migrate up into the headlap zone by capillary action on metal (as it does on slate and wood).
There is a temptation to do the work as you have done, to save material. But since your shingling method cannot shed rain adequately, it is simply not an option for non-experimental architecture projects. I'm using very similar tin cans for my project, which when unrolled are roughly 18" x 7". I'll be shingling with them "vertically", and in that case a standing seam shingle with 1" overlap will give you an exposure of 17" tall and 5.5" wide (93.5 sq in per shingle), while a traditional flat shingle pattern requires headlap, so the exposure will be [(18 - 1) / 2] = 8.5" tall and 7" wide (59.5 sq in per shingle). A 2" headlap would imply [(18 - 2) / 2] = 8" tall and 7" wide (56 sq in per shingle). Again, slate would require a 3" minimum headlap on any but the steepest roofs, but metal may require less -- it's not known.
As you found in this project, it's not possible to flatten the cans ina reasonable amount of time without specialized metalworking equipment, and standing seams require flatter material than is possible with limited equipment, so "flat" shingling without seams but with the necessary headlap appears to be the way to go.
http://www.stoneroof.org.uk/gloss.html
http://www.stoneroof.org.uk/laps1.JPG
http://www.traditionalroofing.com/TR6_headlap.html
--A.J. Tarnas 24.23.127.216 13:14, 30 June 2015 (PDT)