If it is recorded as built in 1920, that is what the insurance will be based on.The most valuable update with regards to insurance is the roof. 

Prices are through the roof in this current market with low inventory and single and multi family properties just don't pencil out.

Got insurance involved and use that money to remodel the entire inside, and add a new roof.

So the major issues in a house are a foundation issue or a structural issue, the next tier down would be a mechanical issue like Electrical, Plumbing, HVAC, then roof - which isn;t an issue a new roof is very common in a fix n flip, and then the outside facade: Brick repair, driveway repair, brick pointing. 

Old properties aren't a bad thing as long as you account for the big four- HVAC, foundation, roof and sewer.

Find something with someone who is boots on the ground, that you have talked to and built trust.

Purchased for $69,000, it needed a full rehab, including a new roof, plumbing, and modern updates inside and out.

Purchased for $69,000, I tackled everything from a new roof to interior updates, transforming it into a move-in-ready home.After months of surprises (and a few headaches), I sold the property for $145,000.

One of the most common mistakes beginners make is jumping into large rehab projects without having a solid team or boots on the ground. 

We have our own design team, contractors, and real estate agency under one roof, which saves time, cuts costs, and improves communication across projects.