Dissolve yeast and sugar in warm water in a large bowl; let stand 5 minutes. Lightly spoon flours into dry measuring cups; level with a knife.
Add 3 1/2 cups bread flour, wheat flour, semolina, and salt to yeast mixture; stir with a whisk until well blended.
Turn the dough out onto a lightly floured surface. Knead until smooth and elastic (about 10 minutes); add enough of remaining bread flour, 1 tablespoon at a time, to prevent dough from sticking to hands (dough will feel tacky).
Place dough in a large bowl coated with cooking spray, turning to coat top. Cover and let rise in a warm place (85), free from drafts, 45 minutes or until doubled in size. (Gently press two fingers into dough. If indentation remains, the dough has risen enough.) Punch dough down; cover and let rest 5 minutes. Divide into thirds. Working with one portion at a time (cover remaining dough to prevent drying), roll each portion into a 16-inch rope on a floured surface.
Place ropes on a large baking sheet sprinkled with cornmeal. Cover and let rise 40 minutes or until ropes are doubled in size. Uncover dough.
Cut 3 slits in top of each rope.
Preheat oven to 42
Throw water onto floor of oven (avoiding heating element).
Place baking sheet in oven. Quickly close oven door.
Bake at 425 for 30 minutes or until loaves are golden brown and sound hollow when tapped.