Supporting a Load on a Roof

A rail mounting system for mounting a skylight or other load on a metal panel roof in which elongate metal roof panels are arranged side by side, with edges of adjacent ones of the roof panels being joined to each other to define elevated roof panel ribs, and panel flats of the roof panels disposed between adjacent ones of the elevated ribs, the rail mounting system comprising:

• a first side rail, a second side rail, a first transverse support member, and a second transverse support member;
• wherein the first and second side rails are disposed opposite each other and spaced apart such that the first side rail extends along a first elevated rib of the metal panel roof and the second side rail extends along a different second elevated rib of the metal panel roof;
• wherein the first side rail includes a first upstanding riser and a first bottom shoulder structure, the first bottom shoulder structure including a first shoulder element and a second shoulder element, the second shoulder element connected to the first upstanding riser through the first shoulder element, the first and second shoulder elements being angled relative to each other to fit closely over an angled profile of the first elevated rib;
• wherein the second side rail includes a second upstanding riser and a second bottom shoulder structure, the second bottom shoulder structure including a third shoulder element and a fourth shoulder element, the fourth shoulder element connected to the second upstanding riser through the third shoulder element, the third and fourth shoulder elements being angled relative to each other to fit closely over an angled profile of the second elevated rib;
• wherein the first and second transverse support members are disposed opposite each other, each such support member extending between and attached directly to the first and second side rails;
• wherein the first side rail extends a first length from the first transverse support member to the second transverse support member, and the first bottom shoulder structure is configured to contact the first elevated rib entirely along the first length so that a first downward force from the skylight or other load is transmitted through the first side rail entirely along the first length;
• and
• wherein the second side rail extends a second length from the first transverse support member to the second transverse support member, and the second bottom shoulder structure is configured to contact the second elevated rib entirely along the second length so that a second downward force from the skylight or other load is transmitted through the second side rail entirely along the second length.