I had to laugh at the idea of 2 x 250w heat lamps in Florida!
Where I live we barely get below freezing and that's only at night, it
never snows, but some people do heat their coops.
When we moved in here there was an old chicken pen. The 'shelter' consisted of a couple of corrugated iron sheets sitting on the chicken wire roof against the garage. That's it. Stupidly, the garage also stops the winter sun getting in because whoever built it had NO regard for the chickens and just did whatever was easiest.
Being one sided and open to the prevailing weather means the chickens would have had nowhere to get out of the wind or even out of the rain unless they were very lucky. I feel sorry for them because it must have been miserable. However, they did apparently survive this lousy treatment.
I'm sure my chookies will be very happy with my planed waterproof, draft free coop out in a sunny spot. I'm also sure they have quite enough fluff to keep warm without lamps!
(Should add, they have temporary quarters atm which they will outgrow in a month or two
)