Top States. Bureau of Labor Statistics data show that forensic science technicians in the District of Columbia lead the nation, with $74,050 in average annual earnings in May 2011. Workers in Illinois made $73,290 on average, crime scene investigators in Virginia earned $71,140 and workers in California made $68,880.alifornia employed the greatest number of forensic science technicians of any state, followed by Florida, where workers earned $46,820 on average. Arizona had the highest concentration of investigators after the District of Columbia, and workers in Arizona earned $55,110 a year on average.
While more expensive than asphalt, metal roofing lasts longer and is more wind resistant. Materials: May be composed of steel, aluminum, copper, or zinc alloy. Steel roofs come with either a zinc coating or painted finish. Copper roofs are installed unfinished and acquire a protective green patina with age.
The most common original roofing material is tar and gravel. A tar and gravel roof consists of layers of asphalt and tar paper (or newer, more sophisticated materials) adhered with applications of molten asphalt. The laminated layers get a top finish of gravel, some of which becomes embedded in the hot asphalt, and some of which lays loose on the surface of the roof.