Studs into masonry or concrete are the default: threaded studs welded to the back of the letter, resin-anchored into drilled holes. It is strong, invisible and unforgiving of a template error, because the holes are already drilled by the time anyone checks.

Cladding and curtain walling usually cannot be drilled, so letters are mounted to a backing rail or a raceway that is fixed through an existing joint. This has to be known at fabrication, because the letter needs different fixings on its back.

Glass and glazed facades take stand-off fixings or adhesive mounting, both of which have weight limits that rule out large solid stainless letters. A design that works in aluminium at that size may not work in stainless.

Whatever the substrate, letters ship with a fixing template so the installer positions from it rather than measuring at height. Measuring on a lift is where fixing errors come from.