Brooding large amounts chicks and temperature change

[HomesteadNowhere]

I'm about to put in my order for chicks. Aiming for 3/8 shipping date. All heavy asst roos. Brown layers asst hens. Freedom rangers, straight run. Total 75 chicks. This is the start of my flock and breeding program which will result with plenty of meat birds too.

I'm planning to look at zip ties to get and color code the different groups of chicks and be able to put them all in one brooder.

I have a heat lamp and bulb. I just got a big heat plate (50-55 chicks max). In the future I'd like to do max 55 and use just the heat plate.
My barn doesn't have electric to it and not able to setup brooder there. I'm planning on building one on the porch. Kind of rabbit hutch style.

I'm wondering a few things because it's been a few years since I had some chicks and only ever did a few at once.
1) how much space do chicks really need? The reading says .5sq ft for wk 1&2. 1 sq ft for wk 3&4. 2 sq ft for wk 5&6. Actual real life I see alot of totes being used up to 5wks old. Space per chick.

2) I was looking at building 2x10ft. 20sq ft. Would this be enough? Would two of them be enough?

3) Average temperature for my zipcode (ohio)... March 50/30*F. April 63/40*F. May 72/50*F. Getting the chicks second week of March puts me at six weeks old mid April, eight weeks old end of April.
I know it depends on what the weather is deciding to do at the time but how do you wean your chicks off the additional heat? Going by ye ol rule of 5*F per week lowering it'll take the full 8wks to get them weaned of it. Yet reading lots of people not having additional heat after 5wks even in winter.

Thanks

 

[Willow2253]

Have one end of your brooding space have heat, and put the food and water somewhere towards the other end. They will be able to go under the heat when they need it and move away when they don’t. The chicks will wean themselves off the heat that way. Any time of year I’ve had chicks off heat by 5 or 6 weeks, because that’s when they’re fully feathered. They don’t need it after that.
With 75 chicks you’re going to need a lot of brooder space. They’ll outgrow 20 sqft pretty quickly. They need space to move around or they’ll end up picking on each other. Plus a smaller space is going to get dirty way faster. 20 sqft packs almost 4 chicks into each square foot. That gives no room to spread out. By the time they’re ready to move out of the brooder they’ll cover half the floor. I would at least triple or quadruple that for them to be comfortable.

 

[WVBirdsAndBees]

You'll need several brooders that size to handle 75 chicks. They grow quick and you're getting large birds. I built mine 6x3, so similar in area, and I wouldn't go over 20 chicks after the first couple weeks.

Using the heat plate, the birds will gradually wean themselves off of it as long as they have room to move around. The old 5 degree trick with heat lamps doesn't apply the same way with the heat plates. As long as it's warm underneath the plate, they will regulate temperature by moving in and out like it was a mother hen. All you have to do is gradually raise the plate as they grow. They will eventually not need to go under it. In my experience, birds raised that way are fully feathered and ready to go a bit earlier than the heat lamp/5 degree method. Once they're feathered and not going under the plate, they're fine outside down to freezing temps. I usually try to choose a warmer day/night to transition and I give electrolytes etc to help ease the move. It's not unusual for them to be ready at 5-6 weeks.

Good luck with the new flock.