;age of the building;have there been any updates to the building envelope over the years (insulation, vapour retarder/barrier, fenestration, etc);are the radiators the older, freestanding cast-iron type, the mid-century baseboards, or the more modern flat(ish) panels;are the hydronic heating lines copper, black iron or {red} brass?

Forced appreciation is great through rehab or tackling mis-management but just regular appreciation is just icing on the cake.  1-4 units is a world with residential agents, lenders, property managers, etc.  5+ units is a different world with different brokers/agents, lenders, etc. 

In this scenario, it could look like no money down to you even though your partner is investing a regular down payment and there is traditional financing involved.

Alternatively, you could take a regular mortgage against one of your existing properties and use the money, this is called a cash-out mortgage.

I've been off of BP for a while, but wanted to give a renewed shout-out to @Chris Mason for his help going through my updated DTI calculation.

Please see updated numbers below in chart that includes insurance. 

These agreements must be entered into carefully and with the help of an attorney who does them regularly.

$125-150/ sf gla for cosmetic update

This site is a gold mine of knowledge, some of the experts that chime in regularly have many decades of Real Estate Investment experience and happily help new people. 

We have many clients doing private lending but I can’t stress enough how you must understand the business and maybe partner up with some experts who lend on a regular basis.