Will my new brooder be warm enough?

[ShawnaScott]

I have been keeping my chickies in a horse trough, but it's getting a little small and it's kind of hard to interact with them in there. I decided to build a brooder that is big enough to fit me in it, that way I can climb right in with them! It is 4' by 4' and is 4' high. I plan to fill it with 3" of pine shavings and keep the heat lamp on. I'm just worried that with the bigger space, my chickies will get too cold. Should I add another heat lamp, plan on more shavings, etc?

 

[ChickenCanoe]

They won't be cold.
The more space they have the better. A broody doesn't heat the whole space, only the spot under her. Just like a heat lamp.
Depending on the age, I sometimes use a second lamp in case one burns out during the night. That would only be if the space was large enough. They need to get away from the heat.