This is the interior of a fixed window. Below it is a sliding screen window, then a sliding single pane window, and finally another sliding single pane window.

So I ask the guy at home depot for the longest, thickest, blackest caulk, right?

Are you saying that I shouldn’t caulk that small exposed area? I’m just wondering why since I don’t know.

My aim is to reduce pests

I am referring to the small 90° gap between the flooring and the metal where you can see bits of exposed concrete. Are you saying that gap shouldn’t be sealed?

What would be the rationale there? Bug prevention?

Very helpful! One of the pipes is hot water to a sink and the other two are cold water and wastewater. In that case I think I’ll do some mdf / scrap wood then fill remaining hole with steel wool I have in hand. I’m guessing the hot water pipe wouldn’t be enough to pose a fire risk with the steel wool / mdf?

As I added in another comment, I’m a tenant.

I’m actually a tenant trying not to deal with my landlord. But I fully agree with your take on it.

I’m actually a tenant trying not to deal with my landlord. But I fully agree with your take on it.

Thanks, are there any that you’d recommend which are heat and rodent resistant?

Not sure if this is being facetious but yes, I do. If the materials I have on hand are a fire hazard, then I’m open to using alternatives.

And if you can swing it, I’d honestly throw another small pump in there for redundancy.

I understand! So then given my limitation, a dual hose portable AC unit is my best option.

Don’t dual hose portable AC units follow the same principle of venting the waste heat outside? As I understand it, the window AC units are still much more efficient at this as they don’t have a hose to push/pull it through.

Thank you everyone. I’ll wipe the area first, then give foil tape a try. I might use mastic for a better seal if it doesn’t cost much more.