Cob: Lets get it back on topic!

[Darel Henman]

What's your point in the quote Mark?

Mark Piepkorn wrote:
> 
>          Umm... "In a fire, cob tends to shrink,

ALL material "tends to shrink" as it dries.  In a fire rapid drying
occurs.  The material itself, considered without water will expand a
little when heated.   (See thermal expansion coefficients for materials
if you wish.)

> thereby enlarging any preexisting cracks in the cob wall.
This occurs in ANY material wall.

> The cracking can lead to structural instability. 
Again this occurs with ANY material.    Except maybe steel which will
melt and lead to structural instability.   Which surprised me because a
wood beam lasted longer than a steel one.  Now they have to protect
steel beams with sprayed on insulation!

>Collapse of cob has occurred during a fire.
Collapse of wood housed has occured during a fire.  Same with steel
buildings.

Just for the record.

Darel