The present invention relates to polypeptides, isolated from Myrothecium roridum, having mannanase activity, catalytic domains, and carbohydrate binding modules, and polynucleotides encoding the polypeptides, catalytic domains, and carbo hydrate binding modules. The invention also relates to nucleic acid constructs, vectors, and host cells comprising the polynucleotides as well as methods of producing and using the polypeptides, catalytic domains, and carbohydrate binding modules.