[Greenbuilding] [BULK] Re: The five hundred year house

[Lawrence Lile]

>From my experience with old barns, it matters not a whit what the walls
are made of - it is the roof that is the weakest link.  

An old barn will stand until it's roof goes, then it will cave in, about
two or three years after the roof develops serious leaks beyond a few
pinholes.  That's in Missouri, with 36" of rain a year.  In the
Southwest, you probably don't even need a roof to keep a building
standing, on the Gulf, a roofless building might croak in less than two
eyars. 

So... Steep roofs last longer than low slope roofs, flat roofs are
asking for trouble, no matter what high tech material you put on them
they will eventually fail.  If you want a roof to last a long time, use
a steep metal roof. (roofers will cuss you)  If you really want it to
last, use a noncorroding material like copper and solder all the seams.
(Spendy!) 

Those 500 year old houses had 500 years of someone steadily fixing the
roof, I'll wager.  They probably had a thatch roof until the 20th
century, not too permanent but cheap to fix.  


Lawrence Lile, PE, LEED AP
Project Solutions Engineering