[Greenbuilding] 500 Year Old Structure

[Chris Green]

RONALD CASCIO wrote:
> ----- Original Message ----- 
> From: "Lawrence Lile" <LLile at projsolco.com>
> To: "Chris Green" <pojeros at telus.net>; <Greenbuilding at listserv.repp.org>
> Sent: Monday, August 20, 2007 9:47 AM
>
> >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.  
>  
> Those 500 year old houses had 500 years of someone steadily fixing the roof, I'll wager. 
>
>
>  Lawrence Lile, PE, LEED AP
>
>
> Ron Cascio said:
>
> I'll second that thought Lawrence.
>   
You win the wager. In the case of slate roofs, the nails holding the 
slates in place would corrode and eventually slate tiles would come 
loose and slide off the roof. They didn't have galvanizing before the 
20th C, nor stainless steel fasteners. If they didn't have iron nails, 
they use wooden pegs---probably oak. Those also would fail after a while.
Ongoing maintenance would be part of the expectations for a 500-year 
house, and so the design would include this.  The entire roof would be 
the weakest point, yes, so planning for future repairs and replacement 
would be part of the initial design process.
The oak timbers used to build roof systems with were quite large (as 
much as 16" x16" ) and when the roofs were built, people-- or at least 
the foresters-- would also plant new oak seedlings so that they had a 
supply of mature trees for when the timbers had to be replaced because 
of infestation by post powder beetles.
That's long term thinking for you.

Not  quite on topic, but in England, in the past, some roofs were made 
from lead. (A horrible thought, I know... ) King Henry the 8th needed  
cannon balls and other ammunition and so ordered all the lead roofs 
removed to supply the metal for the balls. Presumably the ones he was 
fighting in that civil war also took peoples' roofing. So a lot of roofs 
were redone then with something else. That was approximately 500 years 
ago, coincidentally.

In Quebec city since the earliest days it has been city law that the 
roofs have a built in ladder to make access to the chimney easier when 
the inevitable chimney fire happened. When the chimney catches on fire, 
the roof will too, and when buildings are connected as they were in that 
city, whole blocks could burn. Making roof access easier helped prevent 
a lot of this. Again, planning (Fires are a large part of the historical 
reason we have building codes. )

You plan for the inevitable because, well, it is inevitable.

Cheers,

Chris Green.