The weight of roofing construction above the truss/rafter may be estimated with the calculator below[1]:

Clay tile (10.8 lbm/ft2, 52.7 kg/m2)

Concrete tile (9.3 lbm/ft2, 45.4 kg/m2)

Slate - 3/8" thick (12.8 lbm/ft2, 62.5 kg/m2)

Slate - 1/2" thick (18.8 lbm/ft2, 91.8 kg/m2)

Slate - 3/4" thick (26.0 lbm/ft2, 127 kg/m2)

Asphalt roll roofing (1.1 lbm/ft2, 5.4 kg/m2)

Asphalt shingle or asphalt-fiberglass composite shingle (2.7 lbm/ft2, 13.2 kg/m2)

Metal roofing - aluminum or steel - panel, sheet or shingle (1.2 lbm/ft2, 5.9 kg/m2)

[1] https://www.engineeringtoolbox.com/roofing-materials-weight-...