

A new factory can turn almost any plastic into a useful product - ryanb
http://www.economist.com/sciencetechnology/tm/displayStory.cfm?story_id=14255246

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sophacles
If this product can replace roofing boards (usually plywood), would that mean
no more need for shingles either? A close join with good caulking seems to me
a reasonable roofing material. Other similar uses seem to exist in places
where plywood is traditionally used but rots away relatively quikly. Could
this also be used in lieu of pressboard for cheap furnishings?

My big question tho is how much energy does this process use? Is it energy
efficient enough to offset the wood/glue/manufacturing of plywood stuff?

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tjic
As someone who's done a fair bit of roofing, I would never in a million years
butt two surfaces next to each other, caulk them, and call it a roof.

Water is insidious. Things move and degrade with age, with the seasons, and
with the weather.

Two things keep a roof tight:

1) using gravity to help you 2) using multiple lines of defense

On the gravity point, what I mean is that water rolls down hill. The great
thing about conventional shingles is that they overlap by 50% of their length.
For water to infiltrate it needs to get under a shingle and then wick _up_.
Water doesn't tend to do this.

On the multiple lines of defense point, a good roof has two layers of shingle
at any given point (row n and row n+1), as well as tar paper (or better yet, a
polymer sheeting like "Ice & Water Shield".

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sophacles
Fair enough, shingles + tarpaper (or polymer) seem to work as a pretty good
waterproof layer, supported by plywood. I guess it seems to me that the
polymer/tarpaper layer is more for keeping moisture away from the wood than
keeping water out. The shingles seem to be for water.... so if the support
layer doesnt need the protection, and instead offers an impervious barrier,
why not use this plastic sheet in an overlapping manner (think roof slats for
lincoln logs). It essentially becomes shingles + board all rolled up into one.

Edit: it also seems that metal roofing does not follow the same set of
constraings that shingle roofs do, which suggests to me that this plastic
roofing could be very viable.

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tjic
This article didn't make a lot of sense to me.

Plywood can't be recycled because it has nails and paint, but plastic can?

The reason that folks don't recycle plywood is that it's part of construction
debris. When you gut a place, you end up with dumpsters full of random crap:
sheetrock, plywood, studs, pipes, etc. The labor to pick this apart isn't
available at a reasonable price.

I don't see that replacing plywood with plastic changes the economics here.

...which is not to say that plastic sheeting is a bad idea.

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jobu
Most plywood is rotted and worthless by the time a building is torn down.
However, the wiring, most metal, and even the concrete are often recycled.
Perhaps the plastic will be as well if it becomes economically viable.

Right now I'm guessing they're using plastic already separated out by
residents as part of a community recycling program. What I want to know is how
they deal with dirty plastic? No one will want these plastic sheets if they
smell like sour milk.

