Estimate today's cost to replace that element (should be easy if new construction, more difficult to develop an accurate number for an older property, but absolutely do-able ), divide by number of years expected life, set aside that much each year until item is actually scheduled for replacement, adjusting the "remaining life" annually for accelerated deterioration or prolonged life due to well planned and executed preventative maintenance.

It’ll eventually deteriorate to the point where it will be at risk of falling down and you’ll be be spending that full $850 anyways.

The effects of deteriorating affordability, amplified by the rise in mortgage rates since the beginning of the year, likely sidelined some buyers.

The report stated: Foundation walls- concrete deterioration & moisture damage present in some areas.

These properties tend to sit on the market for months vacant and are prone to vandalism or if they are living in it and don't have money to maintain it correctly it will eventually deteriorate further and then they eventual accept the low offers. 

Don't be afraid of tenants moving because when they move it gives you the opportunity to upgrade units so they don't get too deteriorated, you get to charge new tenant more and you increase your property's value.We had (not have) the same problem.

Well, in the area I  was looking, I only found like four multi-family units, one been this one in a multi-family subdivision and the others were really deteriorated crappy properties.

The job market is strong, but we are being told it’s going to deteriorate because of the rates (the feds own words) this will lead to negative wage growth as companies will not need to pay as much to new workers.it generally takes 3-6 months for rates to truly impact real estate values, there is a stand-off between buyer and seller, but the longer rates stay higher, the sell side has to give. the math is the math (obviously there are exceptions for boom towns or gains based on real local reasons.)  

I would expect nearly the opposite of what you've suggested - increasing cost of borrowing, cap rate expansion, value deterioration (alongside affordability).

There are more creative options available in this stratosphere at or around 6.5% but just an illustration of how historic the acceleration and deterioration of readily available cheap credit has occurred.