Is sales tax deductible against building material and its associated LABOR when it is a major home improvement that increases your home value?

If you itemize and you choose to deduct sales tax instead of state and local income taxes, you can deduct the sales tax on the building materials - but not the LABOR.  

You can deduct the sales tax on your home renovation or construction if all of these conditions apply:

• You're itemizing.
• You're taking the sales tax deduction, as opposed to the state/local income tax deduction.
• The tax rate is equal to your state and local general sales tax rate.
• You (or your contractor acting as your agent) purchased the building materials and paid the tax.

See this TurboTax FAQ