Jack is an experienced builder with over $15$ years in the construction industry. He has worked for various construction firms, managing both residential and commercial projects. However, Jack has never independently completed a project from start to finish as the lead builder.

Jack now wants to branch out and start his own construction company. He has identified a promising opportunity to build a new apartment complex in a rapidly developing area of the city. The total project cost is estimated at $$5$ million.

Jack has approached Monash Bank to seek financing for the project. He has provided the bank with his business plan, project details, cost estimates, and projected cash flows and returns. While Jack has significant construction experience, there are a few key risks the bank needs to evaluate:

$1.$ Collateral: Jack does not have enough personal assets or real estate to fully collateralize the $$5$ million loan. His current collateral valued at $$1\mathrm{.}2$ million is insufficient.

$2.$ Credit History: As Jack has never completed a project independently as the lead, he does not have a prior history of successfully delivered construction projects to demonstrate his ability to complete this apartment project.

$3.$ Project Risks: Like any construction project, there are risks around costs overruns, delays, quality issues and the ability to successfully lease$/$sell the completed units as projected.

Given these potential risks, the bank needs to carefully evaluate Jack's loan application and the project's viability.

If Jack is able to achieve an $18\%$ net profit margin on the $$5$ million contract value for this project, what would be the typical $5\%$ builder's retention amount held back by the bank until completion?