In other words, you lose the efficiency of being able to turn over the entire property at once.

Also, 10k is high unless redoing all the ductwork or a really high efficiency heat pump.

You piecemeal rollover the funds into a Roth IRA for some level of tax efficiency. 

If seller won't extend, cancel the contract.6) If contractor bid too high you can either cancel the contract or renegotiate the price.This is more efficient for everyone involved. 

Many other variables come into play with updating windows, my experience has been that the windows themselves are the easy part; it's the management and planning of all the layers around them that make the project easy or hard, cost effective or expensive, efficient or time consuming.

They also usually are more energy efficient as the water is heated as needed and not heated to store in a tank that might not be used for many hours and tanked heaters typically have heated more water than needed (and this is desired because running out of hot water is a bummer).I do not want an annual maintenance effort as large as descaling a tankless water heater at my rentals.  

Might not be the cheapest but is efficient and does solid work.

I have a condo listed for $275K and a house listed for $750K and they can both turn a profit you just have to be efficient and work a little harder than you used to. 

Hello BiggerPockets Community,I'm in the planning stages of an exciting project that aims to construct a sustainable and efficient duplex with a budget of $200,000.

Alternatively, you could install energy-efficient fixtures and appliances to help keep utility costs down for both units.