Depends on the actual deal I have seen 85/15 rarely 90/10 but keep in mind your primary home will have a second lien on it typically if your LTV is over 75%. 

My original plan was to save up for a year and buy my first home.

If he no longer resides in the home, he is no longer a legal tenant.

My name is Nick, I am a Residential/Commercial Broker with Home Front Mortgage.

I'd recommend looking at costs. your build cost is going to be well over other homes because of the fixed costs like slab, Hvac, roof, etc. check the market drivers and weight the benefits of short term versus long term. long term is no furniture and help pays mortgage but at this size it doesn't really cover everything. we didn't find a lot of economies of scale in single family detached. can you build more than one unit?

Home prices always reflect how desirable a neighborhood is. 

Get an estimate from a GC to get a good idea of what is required.Market Comparables: Check what similar-sized homes with finished basements or additional bedrooms are appraising for in your area.

The median home sold price reached $582,329, reflecting a 9.7% increase from the previous year, with a median price per square foot of $325.

Off-market and direct-to-seller appear the best avenue toward decent margins.Pricing & ARVs: Home values in many areas are holding their own, but buyers are getting pickier.

@David YoungTo turn your paid-off home into a successful investment property, start by formalizing a lease agreement, assessing necessary renovations to maximize rental appeal, and calculating your cash flow after expenses.