[Greenbuilding] [BULK] Re: roof replacement asphalt versus steel

[Lawrence Lile]

There is a house just down the street from me - two now that I think of
it- that used exposed fastener systems.  They look pretty good.  A neat
job of finishing and detailing makes the difference between looking like
a barn and looking like a house.  Precise screw placement helps too. A
solid base of plywood that will hold all the screws, not let some of
them hit air and fall loose, would be a good idea.  An underlayment of
heavy tarpaper (30 LB minimum) is recommended, partly because metal
roofs can condense moisture as they cool on a clear night, and partly so
the system can tolerate a pinhole.   

I have lived in several farm houses with extremely old exposed fastener
roofs - literally barn metal - probably 50+ to 100+ years old, and they
were all built before neoprene was invented. No problem.  My own
opinion, not shared by everyone on this forum, is that exposed fastener
metal roofs are better than asphalt from many perspectives, not as good
as standing seam types, but not that bad. I don't think that apprasiers
will make much of a fuss over them.  

The local metal roof manufacturer makes their standing seam out of a
better material - thicker, with a better coating and longer warrantee.
The barn metal style (5V crimp) is thinner material.   That is something
to consider, and this will vary with every manufacturer.  Typically
these are a small-time tin bender serving a 100 mile radius, buying
coils of steel from a larger national outfit, so your mileage will vary
on this. 

People I know with older (+30 yr) exposed fastener metal roofs don't
fool around replacing the fasteners, they go up there every ten years
with a tube of clear silicone caulk and put a daub on the fastener
heads, maybe shoot and extra screw if a corner is loose. Easy work
compared to ripping off an ashpalt roof every 20 years.  On my metal
roof, I made sure there were several large eye-bolts for a safety rope,
so when I have to clean my chimney I don't go skiing off. Oh, and on
exposed fastener roofs, you always end up using the fasteners for
traction. 



Lawrence Lile, PE, LEED AP
Project Solutions Engineering

-----Original Message-----
From: greenbuilding-bounces at listserv.repp.org
[mailto:greenbuilding-bounces at listserv.repp.org] On Behalf Of Ben Pratt
Sent: Friday, August 24, 2007 1:51 AM
To: greenbuilding at listserv.repp.org
Subject: [BULK] Re: [Greenbuilding] roof replacement asphalt versus
steel
Importance: Low


I'm looking at a big difference in cost between exposed fastener and 
concealed fastener. No hard numbers yet, but the contractor gacve a 
rough estimate of 3-4k more for concealed fastener. I could do my 
roof for 7,000us with an exposed faster--and 10 to 11 k for an 
concealed fastener.

-- 
B  e  n  j  a  m  i  n   P  r  a  t  t
Professor
Department of Art and Design
University of Wisconsin-Stout
Menomonie, WI 54751
715 232 1537

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