It isn't likely to be an impact on your existing mechanical systems. Only new work will be subject to new codes. A renovation doesn't normally trigger a requirement to upgrade existing systems (unless it's something dangerous like kob and tube wiring).

Of course, for peace of mind, you can contact your local building department to confirm that new work won't trigger a need to upgrade your mechanical.

Thanks! A tiny bit of hope is returning :)

I am not aware of any requirement to upgrade the boiler system, but you might want to check. Things that are required to be brought up to code are the wiring if you open up walls, the stairs (and railings) up to the main floor if you alter that area at all, egress requirements for safe exit from the basement.

Thanks. We would not alter the stairs beyond stripping and staining. There is an existing closet under the stairs I might like to repurpose as open storage, but would not knock down any walls, just remove the door, paint and change shelving.

If you retain the services of an Architect or qualified designer, he will be able to walk you through all of the latest building code and zoning requirements that are likely to impact your project. He will also prepare all of the necessary documents for a building permit application and can supervise all work to assure it meets code and your needs.