Any lender should be able to easily do a HELOC for you (provided your credit is OK), but a local credit union will likely give you the best deal. 

There are not traditional DSCR lenders that would do that.

Maybe a mortgage lender can chime in.

The primary thing you're going to run into is whether or not a lender, at purchase of the property, will allow there to be a secondary lien on the property.

Do you mind sharing the name of that type of loan/lender that allows you to have the seller carry on a second position?

Thanks,BrettLocal PM here - happy to help identify investment opportunities, provide investment analysis and connect you with contractors, agents, lenders etc etc. kindly let me know and I'll help in any capacity I can.

Maybe they are offering financing because no traditional lender will lend on the building. 

During this renovation period would you, as the lender, want an Actual Cash Value or Replacement Cost policy in place?

or market to Lenders for refi's ? 

Happy to be here - and good to have a good hard-money lender as an option!