"James "Cubby" Culbertson" wrote in message
...
Hiya,
I'm currently constructing an outdoor fireplace. I intend to use
3x3x3/16" angle in a couple of places where I'll need a lintel. I intend
to paint it with high temp paint. Anyway, I'm wondering just what sort
of clearance I need around the steel for thermal expansion? Obviously I
need some mortar in there to hold the bricks together but just not sure of
how much of a gap around the steel I need.
Thanks very much,
jlc

http://www.bia.org/BIA/technotes/t24g.htm

Coefficient of expansion for steel is about 0.000007 per degree F. For
brick about 0.000003. For a 300 degree rise, if the lintel is 24 inches
long, the total expansion of the steel will be --

TE = 0.000007 x 300 x 24 = 0.05 inches.

The brick will expand about half as much, making the differential expansion
about 0.03 inches, totally inconsequential I would think.

Many years ago, my neighbor and I built a brick grill on the property line
for joint use. We used imbedded rebar for the grate right above the
firebox. Never noticed any adverse effects.

SJF