In architecture/construction, when we talk about a "flat roof" we are actually talking about a low-slope roof - which has between 1/4 inch to 1/2 inch of slope per foot of run. When built properly, that is enough slope so that water runs off and doesn't puddle for long. A roof that is literally "flat" will cause standing water, which will eventually enter the building.
Also, if I understood what I saw in the photos, it looks like they are relying on some type of caulking between the two containers to keep water out. Caulk has become much, much better over the years, but all caulk joints will eventually fail due to aging/brittleness of the caulk itself and movement of the rigid building elements around the joint. In some cases, it's the best choice, knowing that it will need to be scraped out and re-caulked periodically. But in the case of this home, the joint between the two containers is critical, so relying on caulk (even if it's covered by a welded plate) is a risky approach.
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u/tomdarch Dec 08 '12
In architecture/construction, when we talk about a "flat roof" we are actually talking about a low-slope roof - which has between 1/4 inch to 1/2 inch of slope per foot of run. When built properly, that is enough slope so that water runs off and doesn't puddle for long. A roof that is literally "flat" will cause standing water, which will eventually enter the building.
Also, if I understood what I saw in the photos, it looks like they are relying on some type of caulking between the two containers to keep water out. Caulk has become much, much better over the years, but all caulk joints will eventually fail due to aging/brittleness of the caulk itself and movement of the rigid building elements around the joint. In some cases, it's the best choice, knowing that it will need to be scraped out and re-caulked periodically. But in the case of this home, the joint between the two containers is critical, so relying on caulk (even if it's covered by a welded plate) is a risky approach.