Heating it's going to be in the teens this week.

[Ohmyheart]

Better to take pics from inside and out during the day to show vent openings.
What about those low vents...they might cause too much draft, especially near the roosts.

The low vents I have closed. I'll check if I can find more pictures from before.

 

[Ohmyheart]

I don't know if these will help, I hope it does.

 

[junebuggena]

I don't know if these will help, I hope it does.

Okay, looks like you've got one big eave vent running along the tall(front) wall. That's the vent that will allow bad air to escape. Open up all the lower vents except for the ones nearest the roost, so that fresh air can be brought in. Good ventilation is just as important in cold weather as it is in hot weather.

 

[oldhenlikesdogs]

Are the eaves open to the outside...gable vents, ridge vent???
Are those low vents still wide open?
Silkies should be fine, @oldhenlikesdogs keeps them without heat(I think)

I have kept silkies without heat. I currently have frizzle bantam cochins without heat. Lows can get in the -20's plus. They were fine in a large insulated coop on the back of our barn. They hardly leave the coop in winter though, so the coop should be big enough.

 

[oldhenlikesdogs]

I personally close most vents in winter and rely on cracks in my door frame to ventilate my bantam coop. It gets much too cold here to leave vents open. If it's warmer than the teens I leave the pophole open, but below that it gets closed up.

 

[Ohmyheart]

Okay, looks like you've got one big eave vent running along the tall(front) wall. That's the vent that will allow bad air to escape. Open up all the lower vents except for the ones nearest the roost, so that fresh air can be brought in. Good ventilation is just as important in cold weather as it is in hot weather.

Thank you. I will open the far lower vent. Yes the front eave is 8 inches and the back one is 4. I was starting to worry I messed up the ventilation.

 

[Ohmyheart]

Thank you everyone. My husband had me worried I needed to add heat with the temps dropping. The girls felt nice and warm when I moved a few of them.

 

[junebuggena]

Thank you. I will open the far lower vent. Yes the front eave is 8 inches and the back one is 4. I was starting to worry I messed up the ventilation.

Just remember that a draft in a chicken coop is not the same as a draft inside a house. In chicken coop terms, a draft is when the birds at roost are in the direct path of the airflow. As long as they are out of the main airflow, and their feathers are not getting blown causing their body heat to escape, they will be just fine.

 

[GC-Raptor]

I think just the top vents are enough in sub freezing temps.
I only have the upper vents open on the high side of the slanted roof.
But my coop is not insulated and no seals around 3 doors or trap door/ramp.
I had no frostbite issues last winter or so far this winter. GC
Edited to add, I also have a heated waterer inside.

 

[lazy gardener]

Just in case you are curious I have 68 trips around the sun been raising chickens for decades.

I live in Canada subject to -40º no light no heat no problems.

You put even my fears to rest. Can you tell us once again, what your coop set up is like? Size of coop, amount of ventilation? Left open year round? How many birds? Breed?