Had a row of 12, each measuring 6ft by 3ft all 6ft 6 high these housed 1 pair of hardbills redpoll,goldie ect.Hawfinch & Crossbill even bred in this size aviary.I had a few 6by6 by6ft6 high for softbills Wagtails,Redstarts ect.If the funds are available i would advise a concrete base to stop vermin digging in,all mine weren't and lost a few birds and nests over the years.