Q: What is the best way to cut fiber-cement siding?
A: Because fiber-cement contains silica, which is considered a carcinogen, you should avoid breathing the dust that can be generated from cutting the material. The most preferred method is to cut with powered handheld shears, or to score and snap the siding. If you must use a high-speed power tool (circ saw, grinder, etc.), then you should work outside, preferably with a HEPA vacuum extraction and certainly with a dust mask. Make the cuts with a special fiber-cement blade, which has fewer teeth that generally create larger dust particles, thereby reducing the amount of smaller, breathable particles.