Beat the rats
You need to ensure your chook pen doesn't attract rodents. First lay a concrete floor and cover it with sand. Young mice and rats can slip through aviary wire, so fit 300mm-wide galvanised sheet metal around the bottom of the pen. Screw the sheet to the frame over the aviary wire, tying it to the wire between the frames.
Beat the heat
Your chook pen also needs a proper roof to protect the hens from the elements. A clear acrylic roof can cause the hens to overheat. It's best to use steel roof sheeting for part of the roof, to give shade. Even better, combine this with reflective insulation and your chickens will be happy.
Step 1: Lay reflective aluminium builder's foil over the existing roof and secure by screwing 42 x 19mm timber battens to the shed frame. Overlap the sheets, if necessary.
Step 2: Screw the steel roofing to battens. To allow in winter sun, leave a small area at 1 end uncovered. The battens between the insulation and the steel provide a layer of still air, which acts as an insulator.