
Been thinking about the attenuation, typically the yeast will consume 75% of the sugars as the remainder are unfermentable dextrins.
1.060 - 1.020 is only 65.4% apparent attenuation and 53.5% real attenuation according to the app I use. (Beer alchemy).
So, two choices I reckon, one, use a high alcohol yeast, WLP001 is up to 80% attenuation, or two, pitch a second yeast.
The other thing I do because my mash efficiency is well over 80% is use less grain to get the starting gravity you want.
Hope that help a bit too!
