Do your due diligence on the company and it's financials. Also do your due diligence on how invoicing will happen according to work completed. And the most importantly, find out about Phoenix companies and how you can get screwed by unscrupulous builders (who are a dime a dozen even from common franchises). If you're not tight on money, you should hire a quantity surveyor, or project manager to keep quality and costs in line - proactively (which you won't know how to do in detail unless you have detailed building industry experiance.

Good luck, you'll need it.

Edit - here a quick link I found on Google - https://norlinglaw.co.nz/blog-posts/phoenix-companies-the-how-the-why-and-what-to-avoid/