I am replacing carpeting with about 350 s/f of natural 18"sq, 1/2" stone. Currently have Potlatch OSB Sturd-I-floor, exposure 1, 23/32 subfloor on 24 OC trusses with a 9ft max span of a total 30 span that terminates midway through a dining/living room where a hallway intersects. (No load...