Help Needed: decide on new brooder in or out of our coop

[TcherDawn]

I think my double Rubbermaid tub is getting too small for my 8 three week old chicks. They are making mayhem and flying into each other everywhere. So I have an idea to make a "brooder" area within our coop. Here is the picture of the space I want to use:

Under the droppings board(after I take out the bags of shavings I have stored under there), I could make a fenced in area out of small chicken wire and two by fours. It will be closed in so the four older hens I have will not be able to get to them, but they can see them. I want to move them out there at 4 weeks old if that is possible. The area will be 81"L x 27"D x 22"H. Their current home is a modified double rubbermaid bin is 48L x 15Dx 12H(really 10 inches high if you take off a couple inches for the pine shavings). The would have no access to the outside run, which is a problem (or is it???)

My other idea is to fence off a part of the run(it is stone covered dog kennel type run-10'x20') and put them in the old Chick n Hutch within the run. The Chick n Hutch measures 42" W x 24"D x 22"H and the attached little covered run measures 58"x40". Here is a picture of my run:

But that leaves the chicks "outside", although within the hutch and covered run, and subject to New Hampshire's vast temperature differences(58 last night, 89 right now!). I am not sure what to do.

I am also worried about Coccidosis. They are on medicated feed, and I only have 4 other hens, but is there an age when they can be in the same area as adult chickens and not have to worry about it?

What would you do if you were me? My 4 year old son is having allergies to the chicks being inside, so I do need a different situation for the chicks soon. Thanks for all the input. These are our very first chicks and I should have had this all planned out, but did not. My fault. Now I feel so confused.
Chick n Hutch and covered run:

 

[DanEP]

Tcherdawn
We moved our ckicks to the coop at three weeks old with about the same temps you mentioned. All we did was to partition of a section of the coop (like a larger brooder) and provided the heat lamp.It seemed like they enjoyed extra room and did just fine.

Dan

 

[JLS]

I moved my chicks out to a section of my existing coop on June 28th (they were 3 weeks old). Of course they are completely seperated by wire. I was VERY worried. Like you, we have to deal with huge temp swings - I live in Maine.

In the begining, I had to put a heat lamp out there because the night time temps dropped to low 50's. That only lasted for a very little bit. Now the chicks are 6 weeks old and mostly feathered out.

I worried a lot but a few friends who raise chickens, including 2 veterinarians and members of BYC, keep telling me that they are farm amimals. They are really well adapted to survive. I hope you find a solution/courage to move them out to the big girls' coop

Keep us posted.

 

[TcherDawn]

This is their current living arrangement. I just can't believe how big 3 weeks olds are! Except my one Cochin, who is literally half the size of all the others(she just made 3 ozs. today)

Thanks for the advise and encouragement. I just don't want to do someting "wrong".