And you have absolutely no place to insult Jay Hinrichs, who has selflessly contributed over 20K posts, and has been in the industry over 40 yrs.

Such that over several years, the property is 100% distributed to the account owner.What if a person contributed $5500 per year worth of value in a property to the SDIRA? 

How might a mortgage be structured if I qualify for the mortgage but I have family who would like to partner on the transaction by contributing the downpayment (20-25%) Can you go conventional on an investor property with this situation?

I will mostly lurk as I do not have the experience to contribute but but there will likely be questions I cannot resolve on my own.

Whether you are looking to be a principal, a deal sponsor, or a passive investor, have something worthwhile to contribute.

., in general it's fine to contribute property into and distribute property out of an entity after a 1031 exchange is complete providing the transfer does not trigger a gain recognition.In your case it might be even simpler. 

Bathrooms, toilet rooms, closets, halls, storage or utility spaces and similar areas are not considered habitable spaces.Habitable space requirementsCeiling height-RequirementsR305.1 Minimum height.Habitable space, hallways, bathrooms, toilet rooms, laundry rooms and portions of basements containing these spaces shall have a ceiling height of not less than 7 feet (2134 mm).Exceptions:1.For rooms with sloped ceilings, at least 50 percent of the required floor area of the room must have a ceiling height of at least 7 feet (2134 mm) and no portion of the required floor area may have a ceiling height of less than 5 feet (1524 mm).R304.4 Height effect on room area.Portions of a room with a sloping ceiling measuring less than 5 feet (1524 mm) or a furred ceiling measuring less than 7 feet (2134 mm) from the finished floor to the finished ceiling shall not be considered as contributing to the minimum required habitable area for that room.Floor space- RequirementsR304.1 Minimum area.Every dwelling unit shall have at least one habitable room that shall have not less than 120 square feet (11 m2) of gross floor area.R304.2 Other rooms.

Both assets have to match in value or one side has to contribute so it's like kind value.

The majority of financiers I've spoken to on the matter have indicated that they prefer to see at least a portion of your contributions remain in the deal.

Retirement account (401Ks, IRAs) contributions must be made from earned income.