Your income and credit, for the finished home's mortgage
A construction loan on a home you will live in is qualified the way a mortgage is: pay stubs, tax returns, bank statements, a credit pull, and the debts you already carry measured against the payment the finished home will have. Federal rules require the lender to verify your ability to repay the permanent loan.
The builder, the plans and the budget
The lender reviews the builder as well as you, including the builder's license and a signed contract with a price. The plans and specifications are what the appraiser values, so they have to be complete enough to value. The budget has to cover the whole build, and a lender can ask for a contingency in it, because the loan funds what was approved and an overrun is yours to find. Someone acting as their own general contractor can meet resistance: FHA, for one, accepts a borrower as the general contractor only if the borrower is a licensed general contractor.
The lot
The lot is part of the collateral and can be the hard part of the file. If you own it, the equity in it can count toward what you bring; if you are buying it, the purchase can go into the same loan. Either way the lender wants to see a path to a permit: a building permit from the city, or from the county's Planning and Building Department outside the cities, and for a rural lot the well or water connection, the septic system under the county's onsite wastewater rules, the fire hazard severity zone, the state fire-safe access rules where they apply, and a coastal development permit if the lot sits in the coastal zone.
A home you will live in, or a house built to sell
This page is about a home you will live in, or a second home, which is consumer lending with the protections that come with it, including the ability-to-repay rule on the permanent loan. A house built to be sold is a business-purpose loan under a different set of rules, closer to a fix-and-flip loan.
Where it is not the answer
If what you want is a finished home and no project, a conventional, FHA or VA loan on a house that already exists is a simpler file that costs less. If the house exists and needs work, that is a renovation loan, FHA's 203(k) or a conventional renovation loan, not a construction loan. If the project is a second unit on a lot you already live on, start on our ADU page: a construction loan is one of the four routes there, and that page says when it is the right one. And if the lot has no path to a permit yet, there is no construction loan for it until it does.