I have made a bunch of warehouse racking models and some other stuff you could use in this map. If you have Hammer set up properly
you'll be able to use them. Search for "warehouse" in the model browser. Also search for "railings", there's a whole bunch of models that you can use here.
As for your warehouse, you need to think about what each surface is made up of. For instance the roof in the first pic is super thick, but I think it would be constructed out of sheet metal (probably corrugated) which means it's actually very thin. Have a look at some reference images and you'll see that it needs to be much thinner AND that it will need to have a bunch of wooden or metal supports (which luckily is an easy way to create detail).
Also your walls are super thick. Before you do too much more just make sure that the BSP is representative of the structural materials that would actually be used here. Google images is your boogaloo partner. Take the time to do up your BSP nicely because when it comes to models you'll find most of the source stuff is laughably inappropriate. Have you planned this map out in advance? You should read the map design principles
we have specifically for Boogaloo.
What you have so far looks great though! Take your time and make it really nice and we'll playtest it when you feel like it's ready!