In balloon framing you close off the top and bottom of the walls.Actually, there has been a fair amount of research (visit the Building Sciences Corporation library for one source) demonstrating that moisture - from external water penetration or air leakage (or, form the interior if open cell foam is used -  can frequently permeate the roof deck causing deterioration (rotting) of the deck itself and/or mould growth.  

The cat had pissed under the couch and the tenants never cleaned it up, so it rotted through the carpet, subfloor, and the smell permeated into the floor joists.

Lived in the house for 13 years and was a hoarder...the smoke permeated EVERYTHING ...

Even if they don't smoke inside or outside the property, the odor of smoke in their clothing gets inside and permeates the place.

In furtherance of such obligation, TENANT AGREES TO PERFORM THE FOLLOWING:1.To keep the Premises free from dirt and debris that can harbor mold;2.To inspect the Premises regularly for the indications and sources of indoor moisture;3.To immediately report to Landlord any discoloration evidenced on walls, floors, or ceiling and/or any water intrusion, such as plumbing leaks, drips or flooding;4.To not air dry wet clothes indoors;5.To always utilize stove hood vents when cooking items that may cause steam;6.When showering/bathing, to always utilize the bathroom fan and to notify Landlord of any nonworking fan;7.To water plants outdoors;8.To notify Landlord in writing of overflows from bathroom, kitchen or any other water source facilities, especially in cases where the overflow may have permeated walls, flooring or cabinets;9.TO IMMEDIATELY WIPE DOWN ANY WATER OR CONDENSATION THAT APPEARS AND/OR DEVELOPS ON ANY AREA OR ANY SURFACE;10.To clean upon first appearance, any mildew from condensation on window interiors, bathroom & kitchen walls, floor and/or ceilings.

There was a stench that came from the local garbage dump that permeated the home inside but not all the time.

Vacancies permeated the market and investors couldn't pay the bills.We have been able to refi and roll over $7 million the past three years and have maintained 75-80% lTV on our properties.  

Im a general contractor ,and entry property investor , with years in property management maintenance ,, youre best bet is to replace the sub floor , ,i wouldnt replace floor coverings over that , its too permeated with pet urine ,  you can try sealing ,but if odor persists you'll have to pull carpet /flooring back up,   John @ 4 Aces Construction   cc 4acesac84302

That crap permeates everything.

Disclaimer: I moved all around the US and chose Byran / College Station, TX as my permeate home and the town I would grow my portfolio.So I turned to Fred Economic Data to look at a comparison of the home indexes over the last 40 or so years. https://fred.stlouisfed.org/gr...As you can see the blue line (Bryan College Station) is less volatile than the red and green lines (Austin and Houston).