Clarification: I have 7 chicks that are 7 weeks old and fully feathered. They have been in their outdoor run for 1 week. It's a large under-deck run, with water-tight roofing and lattice over 1/4 inch hardware cloth for draft protection. The coop is a pre-fab boxed one from Tractor Supply. I converted it slightly (removed nesting boxes & replaced with an additional roost) to provide more space. I will be insulating the enclosed roosting area w/ reflective mylar when the weather gets colder and will also add some tarp to the north facing wall of the run. I have a dryer vent that adds warmth, too. I sometimes run it in the early AM just to warm things up a bit. So is this enough to get my girls (and 1 boy) through the winter, or should I add a coop heater for below zero temps?
Tarp run....yes but do leave room for air to exit up top.
Dryer vent....NO that adds a ton of moisture which greatly contributes to frostbite.
Insulation...no they like to eat it and shiny is the most attractive.
Heater...not in that tiny of a coop. Not enough room for those needing away from it to get away from it. This leads to overheating and possible death.
I recall a few years ago someone heating a small coop and the sleeping birds could not move away from it. They were badly burned.
Small coops and heat lamps=fire. Every year we see posts of coops, barns, houses being burned down because of heat lamps. Not kidding one little bit there.
The prefab coops rarely if ever have enough ventilation. Please post pics of your set up so we can assist.