On Wed, 30 Jul 2003 20:34:28 +0100, John Armstrong
wrote:

but presumably
if it expanded that much, it would also crack the masonry around it.


Thanks to both respondees. I'm not sure how much a 31" length of steel
will expand. My guess is less than 0.5mm. To stop the masonry cracking
at each end of the lintel, I stuck some foam draught excluder onto
each end of the lintel so it will simply be compressing the foam, not
the masonry. I guess plaster will expand when hot too. With a bit of
luck, it'll expand the same amount as the steel - but that may still
not prevent cracks occurring.

Perhaps I'll follow Andrew's idea and stick something onto the lintel,
like brick tiles or something... not sure...

Frank