I have a space under the porch of my house that would make a perfect coop. The floor is cement so will deffinitely need to raise it. What type of subfloor do you think is best? Ply wood? Backer board? Any suggestions are welcome... ALSO when it comes to ventilation, for the coop of 6X6X6 how many ventilation hopes would be needed? I want tha coop to be well ventilated however don't want to make it drafty.