Achieving an antique roofing appearance in the 1920s also produced a degree of roofing services slate craftsmanship unrivalled in other eras, for old slate roofs implied no evident use of metal flashing. When slate replaced, or actually covered, metal for hips and ridges, it had to be cut to specific angles and applied in various ways to create mitered, Boston or fantail hips, and saddle or comb ridges. In this period, it was also less acceptable (even if wiser) to have valley metal showing with the result that valleys were closed with slate and sometimes for additional effect, rounded. If finishing hips, ridges and valleys in slate produced some of the most beautiful slate roofs in Canada, it also created the most expensive. The high cost of slate compared to new synthetic roofing materials ultimately reduced demand and even the luxury trade could not sustain economic volumes of production. The depression of the thirties effectively ended slate as a common roofing material. With texture as the desired effect, the decorative trends in 20th-century slate roofing ranged from the use of heavy slates about two inches thick, graduated coursing employing slates of diminishing lengths, thicknesses and widths from the eaves to the ridge, colour packages and roughly finished slates imitating stone. Small slates and a monogram or single-colour roof, particularly green, were favored in the first decade but thereafter larger and heavier slates with variegated colour effects became popular. The 1920s highlighted slate roofing craftsmanship not only through its more complicated graduated slopes, but also in its charming slate hips and valleys which, in special projects, replaced the almost universal copper and galvanized iron flashing’s of the previous century.