In a message dated 5/13/00 8:43:59 PM, [log in to unmask] writes:

<<Before plywood, how were the flat roofs of 19th century houses and tenements
constructed?  Were they planked, and then coated with bituminous?

This has occurred to me while watching 3-Polish-Guys, Inc., apply rolled
roofing to a pair of 1881 tenements out my window.  I realized that they were
just covering up the existing, without removing it - but then I realized I
didn't know what was "existing".

Sign me,  Notice: Cape Does Not Enable Child to Fly>>


List-

I have worked on several houses of this vintage in and around Baltimore and
DC.  By the time I am the unfortunate slob that has to identify a suspect
leak and try to repair it, there have been 10 or 15 guys there before me,
each with his own idea of what to  put on as the next layer of protection.
In most cases, if a "typical" flat roof on 19th century townhouses exists, it
appears (at least in my experience) to have been the following:

1.  Joists running front to back, usually bearing on a beam somewhere about
mid-span with the beam running from side to side.

2.  Wood plank decking approximately 1" thick and of various widths ranging
from 6" to 10".

3.  A flat-seamed metal roof was then installed directly on the planking.  I
have never seen any type of paper as a first layer, but doesn't mean of
course that it wasn't done.  Note:  I have seen 1 or 2 standing seam metal
roofs also.

Based on observations, I would hazard this scenario as a "typical" repair
and/or maintenance cycle:

1.  Metal roof is painted when new.
2.  Metal roof is painted several more times for the first few decades of its
life.
3.  Metal roof develops leak (s) and solder or metal patch is used.  More
paint etc.
     This keeps the roof serviceable for another few decades.
4.  Roof is now 50 -60 years old.   Leaks keep developing.  Roofing mastic
made of asphalt, bituminous etc. is used as primary patching material.  Big
mistake...caustic, makes the deterioration of the roof accelerate.... More
paint.
5.  More asphalt,  more paint...gosh this old roof isn't worth repairing
anymore, but those Polish Guys want too much to tear it off.  Hey, I
know...let's pour asphalt over the WHOLE THING!!!!
6.  Asphalt cracks .... soon.  Keep patching with asphalt...after all, the
can and the man at the store says it's for metal roofs.  (This is one of the
greatest marketing schemes ever devised by the petroleum industry...get folks
to put something on their metal roofs that rots the shit out of it...and then
sell them more of it so they can continue to "patch" it.  Wink, wink, nod,
nod.)
7.  Finally, hire the Polish Guys to cover with rolled roofing.

Respectfully submitted by one who has spent too damn many hours on hot metal
roofs wanting to punch the son-of-a-bitch who started the cycle  of bad
maintenance in the first place...probably before I was born...so he is either
dead or an old man, in which case I wouldn't really punch him, but give him a
stern lecture on how bad asphalt is for metal roofs.

Anyway, for what it's worth...

Mark