Do I have room for more chickens

The only one who can really know if you have room for more chickens is you. There are so many variables such as snow load, climate, nature of each particular breed of chicken, etc. Are the chickens you have now fine? Does it seem like there is extra room? As a general rule, each chicken needs 4 sq ft of space in the coop. If you get winters with snow, you need more space than that. Your coop is 40 sq feet. 40/4=10. The maximum number of chickens you can have is 10 chickens. Right now, you have 6 chickens. You should be fine getting 1 or 2 more, but I would not max it out and get more than that. 

Mine stay indoors a lot when it rains or snows and to eat, drink and lay eggs (their choice, not mine), so I have more space per bird.

 

Can I ask, when you give the dimensions of your coop are those the internal house dimensions or are they the whole dimensions of a pre-fab coop?

Good question, that would change things up a lot. 

I have a 4'X8' coop (external dimensions, I guess about 4" smaller on each wall inside) which has housed 8 or 9 heavy breed chickens for over a year. My birds only go inside the coop to lay eggs and to roost for the night...and sometimes to check on the progress of someone who is laying an egg.  Because I have a well sheltered run, they can go out into the run during rain, snow and wind, and haven't seemed to suffer in really cold, Colorado winter weather.  There is an attached chain-link dog run that is about another 300 square feet, but they don't like it much in when there is more than about an inch of snow.  

 

While my chickens complain to me more in the winter because they don't get as many opportunities to free range, they have never seemed the need to peck and fuss with each other, which gives me the idea that they have more than adequate space.  The roosts are pretty well packed at night, but I bet that is a good thing during cold weather.   

Were you giving dimensions of your run in your last post?  If so, and if it is going to be covered, your chickens might make good use of it in winter, depending on breed.  If they are sturdy, winter hardy breeds with full feathering, chunky body, and rose, pea, or walnut combs, they will likely use the run during winter, but remain in the coop on particularly cold or windy days.  A slender little ornamental bantam with a large single comb, on the other hand, might suffer more and need to stay indoors in winter.

Chickens actually do pretty well in the winter, although mine don't like more than maybe 1/2 inch of snow.  My chickens are all cold hearty breeds, meaning, as janiepeters stated above, they are larger of body and smaller of comb (I guess large combs can get frostbite).  I don't think there was a day all winter where they did not come out of the coop and into the run.  Here's a photo of my coop/run setup.  I now have an additional exterior run attached to the primary run that is accessible through the little door in the front.

 

 

They didn't use the exterior run much when there was any snow, but if I'd come up with a snow shovel and clear a path for them, they'd come out and range around even on very snowy days.  Probably not much for them to forage, but they seemed to enjoy getting out of the run anyway.

Hey lulu and others Jusst want to tell u all that we share the coop so we wanna get 2 more bantys ok so r coop is 6 ft in L 4ft in W 4 ft in H all but 1 or r birds roost ( silkie) and the birds we have full size Amber link buff bramha bantys silkie cochin silkie mix millie dur flur. We have 1 6ft roost but have room for another also every morning the girls are let out in their 25ft by 20 ft run and at least 4 hours every day get let out.