[Ravensfort] showers / Re: [rfofficers] Gundy's Find

[Catie Clark]

If the issue is weight, here are some numbers to be 
considered.  Looking at these, I think 10 lbs a shower wall 
is maybe a bit optimistic (unless we found just the right 
plastic)

plywood (b/c, outdoor grade)
1/4" 4x8 sheet 25# (0.7812 #/ft^2)
1/2" 4x8 sheet 50# (1.5625 #/ft^2)
3/4" 4x8 sheet 75# (2.344 #/ft^2)

To get to marine plywood weights, multiply those numbers 
above by 1.25.

Steel sheet, mild cold rolled

32 guage/0.0097"  0.4057 #/ft^2
28 guage/0.0156"  0.6534 #/ft^2
26 guage/0.0179"  0.7486 #/ft^2
22 guage/0.0299"  1.25 #/ft^2 (Ambrose: 1.6#/sqtf)
18 guage/0.0478"  2.0 #/ft^2 (Ambrose: 2.6#/sqft)
I went back and looked at Ambrose App C where his sheet 
steel weights reside and his weights are for painted, not 
bare, steel sheet.  The other weights are all based on guage 
thickness multiplied by American standard guage weight of 
41.82#/inch thickness steel plate (mild cold rolled)

Corrugated "tin" roofing:

varies depending on age and manufacture
between 0.7 and 1.25 #/ft^2
(including framework and fasteners)
[citations on request...]

a lot of the old "tin" roofing, the stuff from the 19th and 
early 20th century was actually very thin sheet steet or 
sheet iron which was plated with tin, tin and lead alloy or 
zinc, as a rust proofing.

Plastics

I think we could all profit from a little more research into 
the structural plastic stuffs. I'm not at all familiar with
what ever FRP is, for example.  The stuff used up at 
Yellowstone is twice the weight of wood to achieve the same 
structural behavior - but it is able to survive Yellowstone 
winters, the acidic environment of the geothermal areas and 
intense UV exposure at 8000 elev.  But heavy and expensive.

The problem with plastics is that there are so many of them 
and all with widely varying properties.  It is no longer 
true that all plastics die in sunlight or break down 
chemically in terms of a few years - but the high grade 
stuff is never cheap.

And yes, Sainted David, tin roofing works because of the 
support structure that supports it.  I have nothing against 
very thin guage metal of any composition if it has adequate 
support.  But I was responding to specifically to what I 
interpreted as a suggestion for unsupported, uncorrugated 32 
gauge mild sheet steel, which can be mangled in your hands 
(if that's an exaggeration, then it's a very slight one; 
I've worked with the stuff as sheathing on boats - it's 
insubstancial - we used it just because it was flimsy enough 
to be easily workable).  But add support structure & 
corrugation and thinness of guage becomes a minor issue. 
Both corrugation and support change the story - but support 
networks add weight, and I was assuming weight was an issue 
here.  Lathing is not weight free - you have to account for 
its weight too, in addition to the sheet metal.

Is there a reason no one has considered corrugated aluminum?

I think one could get away with 26 guage of any metal 
unsupported ( or with one or two brace pieces only) but if I 
were building this thing for me, I'd want to run a test 
piece first to be sure.  But if there were old corrugated 
tin or "tin" roofing about for the taking for very little or 
no money, I think the weight would be a small issue. I'm a 
big fan of really really cheap or free if whatever was 
available actually worked, and then the weight could be 
looked at as an opportunity for some extra athletic workout 
(says someone not likely to have to move the showers...)

ttfn
Therasia, the grumpy uncaffeinated one
(I can't spell either - cope.)