Get cold hardy breeds. I'm not sure silkies fall in that category. Insulation will help keep coop warmer. Most important though is good ventilation, and avoid drafts. ( draft defined as wind blowing directly or semi directly to ruffle chickens feathers) Gentle air flow to remove moisture and ammonia (byproduct of chicken gumdrops) is IDEAL. Keeping water and feed outside is preferred, if you want to minimize moisture from water inside coop. Get a heated dog bowl for water like I use. During night , chickens do not need water and feed as they sleep.
On extremely cold days, if chickens do not want to go outside, then place feed and water inside. Remove for the night.
WISHING YOU BEST... and