In a large bowl, mix warm water, yeast, and sugar. Let sit for 5-10 minutes until frothy.
Stir in melted butter and salt. Gradually add flour, 1 cup at a time, mixing until dough forms.
Knead dough on a floured surface for 8-10 minutes until smooth and elastic.
Place dough in a greased bowl, cover, and let rise in a warm place for 1 hour, or until doubled in size.
Punch down dough, shape into a loaf, and place in a greased 9×5-inch pan. Cover and let rise for 30-40 minutes.
Preheat oven to 375°F (190°C). Bake for 25-30 minutes until golden brown. Cool for 10 minutes, then transfer to a wire rack.