Oh gosh...I remember going through this last winter. Trying to decide what would work for warmth. I dabbled with 75 watt black light bulbs for 0 or less and then when it was -20 the brooder bulb. It always scared me to use that thing though. I'd say little prayers before getting up out of bed in the am and I'd look and thankfully the coop was still there. Looking back I decided that they were all fine probably without it. And my efforts were probably just busy work for myself. They roosted alot during the cold snaps and that's what they'll do to get through it. The only time I saw my birds use the red lamp to warm under was at -25 F. So if that helps you with any decisions on what to do there.
One tip for you: I found this nice little company out of Iowa called Premier 1 Supplies. They have a hard plastic--sort of tough high end heat lamp for lambing. It's larger than what I thought it would be but at any rate: It's a $30 Lamp ($10) for shipping and I'm going to use that this winter on those nasty colder nights. If you use those metal brooder type ones: double triple secure at 2 or 3 different points of the lamp. Then take some chicken wire and put it around the lamp so if the socket and bulb slip from the frame work of the lamp (which is usually their fail) it won't fall away from the lamp and into the bedding. I always try to strategically put it where fluttering wings won't bang it around too. Keeping out of wings' reach is a good thing.
One tip for you: I found this nice little company out of Iowa called Premier 1 Supplies. They have a hard plastic--sort of tough high end heat lamp for lambing. It's larger than what I thought it would be but at any rate: It's a $30 Lamp ($10) for shipping and I'm going to use that this winter on those nasty colder nights. If you use those metal brooder type ones: double triple secure at 2 or 3 different points of the lamp. Then take some chicken wire and put it around the lamp so if the socket and bulb slip from the frame work of the lamp (which is usually their fail) it won't fall away from the lamp and into the bedding. I always try to strategically put it where fluttering wings won't bang it around too. Keeping out of wings' reach is a good thing.