I had the same problem
Makers charge a fortune for a tube to go over the light in the loft...So
Cut the ends off a ali beer can put the tube over the light leave top open insulation around tube ..beer can not big enough..baked bean can.. not big enough One foot plastic down pipe.. not big...
I have a new bungalow that has a vented roof hence hot in summer and cold in winter.
I want to put a model railway in the loft and wondered the best ,and most cost effective way to create a large insulated box for me and the layout. The loft floor has been decked with chipboard over 8" Rockwool...