Walking on a Spanish tile roof
I wanted to tell you and your readers that I own a 1928 Spanish Colonial Revival with a "tile" roof. Your comments about preventing cracking is very beneficial and I've referred to them several times since I've been following your site.
Just a little trick I learned when dealing with any slate/clay tile roofing:
Take several sand bags and fill up to about 75% of capacity (40lbs).
Place two sand bags approx. 12 ft apart on your roof.
Place a 2x12 on "top"of each sand bag and allow your weight to contour the sandbag around the tile.
From that point you can work out in any direction to plaster windows/walls/etc.
Retrace your steps and "breakdown" each section to the beginning.
I've used this technique several times and it works great. All you need is a bunch of 2x12's and some sandbags. Not only does it save on roofing repair expenses but it allows you to cover a large area. It's almost like having scaffolding on your roof.
Take care Reggie!