Paint for coop interior? Spacing for roosts?

[BelindalM]

Paint
I was not planning to use paint on our interior where the chickens could reach. However, a light rain caught us overnight with the two side walls off. There are now specks of mold/mildew in some areas. Though this won't happen again, I'm nervous about how little moisture it took for all this mold to spring up. I treated with white vinegar and a fan. The results weren't great so I'm using diluted bleach today.
Did you paint your interior walls? If so, with what paint? (We are already over budget, so economical would be nice.)
I also worry about Kilz or Zinsser mold killing primer being too toxic. If I use a top coat of nontoxic barn paint, would they still peck it off and get to the stronger Primer?

Roosts
We put the 4 roosts 18 inches apart ( 2 of those are 2x2 and 2 are 2x4). That really only gives them 14 inches between the roosts, so they won't be able to get much of a running start. Will my 10 week old chicks be able to hop onto a roost with that spacing? Will it be okay when they are grown? These are large breeds: Orpingtons, Barred rocks, Blue Rocks, Rhode Island Red/Australorp mix, Marans, and one Wyandotte.
We put 4 roosts because we have 15 chicks and I wanted to give them a choice of roost width. Before they are grown will will rehome some so our 4x8 coop will only house 8 chickens. Then we could remove 1-2 roosts, if the spacing won't work.
Crooked picture attached to give you an idea of spacing.
Thanks for reading my rambling post. I appreciate any advice!

 

[Sally PB]

Did you paint your interior walls? If so, with what paint? (We are already over budget, so economical would be nice.)

I painted the interior of my coop white, with 3 coats of paint. I haven't seen any sign of chickens pecking at the paint. I picked white to keep the interior brighter and the cost down. I got a 5 gallon bucket of exterior grade paint($50...?) and have used it for other projects too. There is still some left.

Before they are grown will will rehome some so our 4x8 coop will only house 8 chickens. Then we could remove 1-2 roosts, if the spacing won't work.
Crooked picture attached to give you an idea of spacing.

Chickens need room to "glide" down from roosts. Figure at least as much room horizontally between roosts as the roosts are high off the floor, and more than that would be better. If this isn't possible, then put them lower until you rehome the extra birds.

Then we could remove 1-2 roosts, if the spacing won't work.

That would be a good idea. See if they have favorite roosts, and take the others out. Two 4' roosts would be plenty for 8 birds.

And,

 

[Nodakj]

I used a lime whitewash on the insides and on my roosts. Pretty cheap and i guess some big operations do the same. Just google it to find the recipe.

 

[Ted Brown]

Ditto the above. Easily renewed and is reputed to deter buglies, historically used on barns back in the day.