HARP is the Home Affordable Refinance Program designed by the federal government to help homeowners who could not refinance because their homes had lost value. It's strictly a refinance program available to homeowners who meet specific criteria (for instance, they must be refinancing a loan backed by Fannie Mae or Freddie Mac). It's not a construction loan program.
However, there are programs that allow you to finance the construction of a new home on property you own. You can choose a construction loan, and then pay it off with a permanent mortgage, or do a one-time-close loan, which comprises two phases -- a construction phase, in which you pay an interest rate typically based on the Prime rate, and a permanent phase, in which the loan converts to a "regular" permanent mortgage at the rate and terms you negotiate with the lender.
Both choices have their pros and cons. A one-time-close means only one application and set of documents, but you have less negotiating power when it comes to the permanent loan. Doing it in two stages may get you a better permanent rate, but there will likely be additional title and document and application charges.
For government-backed construction financing, you may be able to get VA financing to build a home, if you're eligible and can find a lender willing to do it. The VA has no problem with it; it's finding a lender that's the challenge.
If your property is in a rural area and you meet USDA income eligibility guidelines, you may be able to use their construction-to-permanent loan program. Here are the details: https://www.rd.usda.gov/files/RD-RHS-SFHGSingleCloseLendersBuildersInfo.pdf
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