Silica Free News has published a free reference guide ranking countertop materials by crystalline silica content, aimed at ADU builders and contractors specifying kitchen and bath surfaces on accessory dwelling unit projects. The guide is available now at silicaguide.silicafreenews.com.
The short version: not every "low-silica" or "silica-free" label on a spec sheet means the same thing, and that gap matters most on ADU jobs — where one contractor often makes the material call directly, without a design team or materials consultant layered in between.
ADUs compress a full kitchen and bath into a small footprint, and countertops are one of the first finish decisions on the punch list. Builders who don't normally spec stone are increasingly the ones filling in that line item, often on a fixed-fee build with no separate materials spec to lean on.
The guide ranks 15 material categories from highest to lowest silica content — starting with quartzite (90–99%) and ending at 0% for solid surface, recycled glass, paper composite, and stainless steel. Standard engineered quartz runs 85–93%. Granite ranges 10–45% depending on quarry. In between sit the categories builders hear about constantly but rarely see defined side by side: Q40 and Q10 engineered quartz, sintered stone, porcelain slabs, and the handful of engineered surfaces that test under 1%.
Worth noting: the guide keeps Q-ratings scoped to where they actually apply. Q10, Q40, and Q-Zero are quartz-industry shorthand — they describe engineered quartz products specifically, not sintered stone, solid surface, natural stone, or recycled glass. Those categories are classified by tested silica percentage instead, and the guide uses silica content, not the Q-number, as the organizing measure across the full material list.
That distinction has gotten more relevant as states act on crystalline silica exposure. California's Cal/OSHA rule took effect in 2025, and other states have since issued their own safety alerts and proposed legislation covering fabrication and installation. None of it changes what goes on an ADU spec sheet directly, but it is shifting which materials builders default to when a client asks the question.
The guide is free to download at silicaguide.silicafreenews.com and takes under a minute to claim — enter an email and select a role (builder, designer, distributor, or other) to get the download link, plus ongoing coverage of the countertop material market from Silica Free News.
Silica Free News is an independent trade publication covering the silica-free and low-silica countertop industry across North America. The guide, like its reporting, is built from manufacturer safety data sheets and independent sources, not marketing copy. Full coverage is available at silicafreenews.com.