A home equity or construction loan would be a great way to finance your dream project. This allows you to complete your project now, while paying for it over time.
You only make payments on what you actually borrow, not the entire loan.
If there is a large construction project happening, the bank will use the plans and budget for the home appraisal. They will base the loan amount on the future value, not the current home value. This allows you to use the future value of the home to pay for those improvements now.
Helpful resources:
5 Basic Types of Mortgage Loans