I personally think the ice water dunk is cruel and I've heard from a number of people that tried it that it really didn't work. So we don't do that. We use our laundry/mud room for a brooder area, infirmary and broody hatching area. Its a large room (just off our kitchen), so it doesn't bother us that we have chickens in the house.
We cover the hall tree bench with a towel or blanket. We set the hen up in this room with feed, oyster shell, grit, roost chair, and water BUT no nesting material. The broody has the whole room to walk around in, but nothing to nest on. She can sit on the hall tree bench, but can't make a nest. We let her outside every day, but never let her back to the hen house during this time, so she can't make it back to the nest boxes. I give the hen extra protein and calcium when they are broody. And they still get any treats the rest of the flock may be getting.
If you catch them immediately, it only takes a short time before the broody loses her Marlene Dietrich voice and acts like her usual self. In this picture, we also brought in a bale of straw so Lou would be up off the cement floor in winter.
Here is Lou in our portable wooden broody nest with her 5 chicklettes in this room. These chicks are now 4 weeks old.
When they molt , HOW long before they start laying again ?
With molting, I've found each of our birds is different. Our Buff Orp started molting Sep 11 and started laying eggs again Oct 1. Our Partridge Plymouth Rock didn't lay for about 2 months due to molt. Our Silver Lakenvelder is a very slow molter, taking about 2 months to complete. But she continues to lay one egg each week that she is molting.