Foremost in the mind of the lender is how they are going to be repaid. Depending on the scheme, this can be one of several ways, which may or may not need to be evidenced to the lender before completion of the loan.
Of course, the most common would be to sell the development once it has been built. For smaller schemes, this may mean just advertising off plan as soon as possible with a local agent. For larger schemes, this may mean building a show home, and sourcing pre-sales from a local housing association, or specialist off plan house buyer.
If using a refinance as the main mechanism to repay the development loan, then the lender may require a decision in principle or offer letter, to prove that this is a viable exit solution.
In some cases with a commercial development, such as with a hotel, office or shop, you may be building the project on the basis that it will be tenanted when complete. If this is the case, the lender will need to see some form of contract/LOI/lease agreement, to evidence that your exit is suitable.
Development exit finance is also available for both refurbishment and new build ground up developments when the developer wishes to repay the development loan and release some equity contained in the project. This is short term loan rather than a mortgage pending sale of the property.