You might think that the building you're going to lease is "up to code", or if it's not then it's the landlords problem. Don't be so sure. It's not uncommon for landlords to include a "Compliance with Laws" clause in your lease agreement which can create some real headaches for you.
When negotiating your commercial lease, you are going to want to look into the building compliance terms and ensure you won't be on the hook for any future compliance expenses.
One common example of this kind of issue is complying with the Americans with Disabilities Act (ADA), which governs building access to people in wheelchairs or who are otherwise disabled and need special building provisions. ADA holds liable BOTH the landlord and tenant of a commercial property for maintaining access to disabled persons.
Additionally, you are going to want to investigate any potential environmental issues with your commercial space and make sure your lease agreement include favorable terms for you. It's not uncommon for commercial tenants to be held entirely liable for any expense resulting from pollution that surfaces during your tenancy.