My boss is using me. How do I stand up and ask for more money?

Just started working with my wife as managers of an apartment complex 4 months ago. We get free rent and a salary on top of that. We get to paint our apartment, and decorate however we please. We wrote up a contract describing our job description but in our busy schedules, niether the owner or ourselves have had the time to sign it. Now I'm getting all kinds of things added to my list of maintenance duties that were never discussed. Formica, flooring, and for the next month, I'm up on the roof helping out a roofing company tear off old shingles and roof decking... I'm not getting paid anymore. And I still have to do maintenance on the rest of the complex, run a commercial pool, and walk the property for trash... not to mention other manager duties.