So for example, if all 4 of the HVAC systems in this 4 plex are 10 years old, and the typical lifespan of a HVAC system is 20 years, then you can assume that you'll likely have to replace those HVAC systems over the next 10 years.

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Still working full time but need to replace my wife's income.

All they would ever do was come in with a shampoo machine and suck the water out but it still smelled and they never replaced the carpet.

They might just barely pay it off with a 7 year if they're lucky enough to have a low vacancy and not have any roofs to replace or boilers/furnaces go out, ect.

Down the road, when this roof needs to be replace, will the next contractor have to replace the plywood to install a new rubber roof? 

Also I need references to sub out work for:Floor replacement, (need new hardwood installed). 

What things have you seen that have alerted you to issues that would require repair and/or replacement?

What things have you seen that have alerted you to issues that would require repair and/or replacement?

Due to the age of some rentals, other items to consider is concrete driveways / walkways, septic and sewer (if property is on well/septic), landscaping, entry doors / screen doors (my tenants like to ding them up moving stuff in/out, so replacement is about every 5 years or so.