To access inside the roundhouse for cleaning track and getting at a mis-behaving locomotive, I have not glued the roof sections down.
However, I did glue these together in three or four groups. This makes removing the panels easier. I also marked them discreetly on the inside in case I get them mixed up.
To help hide the split lines between the individual roof sections, I applied a strip of .010″ thick by .100″ wide styrene along the seam.
One very common roundhouse feature, that does not come with the Walthers kits, is a firewall. Since my roundhouse is fairly large at 15 stalls, I added a firewall made from Walthers brick sheet and styrene strip. Instead of the “tile” style trim along the tops of the wall supplied with the kit, I opted to instead apply styrene strip as concrete trim, a la CPR John Street Roundhouse.