For newly constructed, purchased or renovated properties and also retroactive generally over the last 10 years, building components are properly classified into individual units of property and accurate recovery periods for computing depreciation deductions.

The primary goal of cost segregation is to identify components that are not real property and therefore can be depreciated faster (typically over five, seven, and 15 years).

With older buildings, we need to be careful with the components of the building, such as roof, driveways, mechanicals.If you have to change the roof in the next 5 years, there goes any cash flow.

Does anyone have any actual data on the return on this component (previous appraisals, paired sales analysis, comparison on new construction with/without rooftop decks)? 

I think, in general, unless you're an extremely high W2 earner just looking to get into real estate for tax purposes, buying for cash flow gives you the durability to weather market fluctuations as you're never in a position where your back is against the wall and you need to sell... unless you have debt coming due.Now, that being said, if the true cash flow, after allocating for all expenses, vacancy, maintenance, capex, etc. is in the black, then I think taking a 5% CoC return in an appreciating market isn't a bad move, especially if there is a component of value-add. 

This deal, valued at over €200 million, positions TPG to take advantage of Ireland’s robust housing demand, especially in the greater Dublin area where Quintain’s land bank could produce up to 7,700 new units.France: Quick Office Lease-Up at Paris Mixed-Use ComplexIn France, the office component of the Emblem complex near Paris is quickly filling up.

However, the GC I hired was wildly incompetent so they missed critical components like the HVAC, we had to redo the sewer drain to the house, holding costs delays … you name it.

On average, 20% to 40% of those components fall into tax categories that can be written off much quicker than the building structure.A Cost Segregation study dissects the construction cost or purchase price of the property that would otherwise be depreciated over 27.5 years for residential property or 39 years for commercial property.

The numbers I'll provide are just an example of a random heat pump, and the actual performance can vary slightly depending on the manufacturer, design, and the components they are combined with.

I have recently reached a point where the existing electrical components of the home are in need of replacement.