What is the definition of major renovation in Itemized deduction - General sales taxes?

[onlinetax]

Background: I am planning to use State and Local General Sales Tax Deduction worksheet in 1040 schedule A, itemized deduction. 

- Enter on line 7 any state and local general sales taxes paid on the following specified items.

- substantial addition to or major renovation of a home

What counts for substantial addition to or major renovation of a home? For example, is adding central air conditioning considered as "substantial addition"? Is replacing furnace a "major renovation"?

[DawnC]

No, those would not be substantial additions.     Adding a room or pool would be a major renovation.  Sales Tax on Renovations.    To qualify, the home improvement must:

• Add materially to the value of your home
• Prolong your home's useful life significantly
• Adapt your home to new uses