Alright guys, had the builders in for a day last week, five weeks late. Fifty plants all in my 4x4 tent, minimal air flow and one t5 for light. At times the builders were about 6 feet away from the grow. They only did half a days work but managed to seal the loft, leaving me no air out. Spoke to the landlord, who said the builders are coming back to put vents in the eaves which will give me back my air out. Farce and put me well behind with flowering but will work in my favour once its all done.