Armstrong Biome Rainier (ST254) shares Natterhorn's 25-29% light reflectance, giving the Montane design two mid-tones. Rainier's swatch appears as a cool medium gray with straight grain and small knots, where Natterhorn leans warm.
Rainier can go over Armstrong's S-1840 acoustical underlayment, with conditions. Bond the underlayment to the subfloor and the planks to the underlayment with S-995 or S-1000; S-319 Roll Strong isn't approved with S-1840. Over concrete, the slab must test at or below 93% RH and 7 lbs. per 1,000 sq. ft. per 24 hours. Installations over acoustical underlayment can be more prone to indentation, so weigh that where heavy furniture or rolling loads are expected.
Finish: Diamond 10 Technology
Installation and warranty: Full-spread glue-down. The 30-year commercial limited warranty requires a recommended Armstrong adhesive, such as S-995 or S-1000, installed according to Armstrong's instructions.