In the "Shopper's Guide" titled All About Installing Hardwood Flooring Over Radiant Heat, it states that Quartersawn wood is not usually available factory prefinished. Why is that? And is maple (and other wood types) readily available in quartersawn, or is this cutting process usually reserved for red and white oak? Thanks.

Due to the high cost there is not much demand for Quartersawn flooring to have it set up for it being prefinished at the factory on a regular basis.

There is one company that I know of that manufacturers prefinished engineering flooring with a thicker Quartersawn top wear layer http://www.listonegiordanopasadena.com/
They also manufacturer other species as well.

We do retail a lot of "High End" unfinished 3/4 thick solid quartersawn red and white oak, maple etc. and then job site sand and finish them but its all custom milled long lengths. Costs for the flooring alone can run anywhere from $7.80-Up depending on wood species and widths desired.

Jeff Hosking