Cast iron feeds are also prone to corroding & bursting especially if it's high PSI steam.

In Pennsylvania, can I legally put a clause in the lease agreement requiring the tenant(s) to professionally clean the unit and steam clean the carpets before vacating, regardless of condition, as part of the lease?

The carpet was not professionally steam cleaned.

If not, maybe the problem that caused their need has long ago been "handled".Also age of heating system and type (forced air vs steam vs coal).A property inspector will give you a written report of what is found out of line.Good Luck!

Based on what you've described, this sounds like moisture on the surface of the wall, which would be caused by excess moisture in those areas from the Tenant not ventilating the bathroom while showering or cooking with a lot of steam in the kitchen area.A contractor can put a moisture meter in the sheet rock and quickly tell if there is any moisture inside.

I'm not familiar with your song, but when I see "clouds" it's full steam ahead. 

I have paid closer to $100 to have someone come in and steam clean.

Airbnb was just starting to gain steam, so we gave it a shot!

There are also forms for the required window guard notification, and a new one coming up for 2022 for radiator covers if your unit has steam heat.

I ended up steam cleaning for a week.