I have cleaned houses for many years. For a move in/move out cleaning you need to double the number of hours you would usually need to clean the house. Add an hour because you are unfamiliar with the house.
Most houses that size take 5 to 5.5 hours to clean. Because it is super dirty you should add 3 or 4 extra hours. Time for washing walls would be approximately 5 to 6 hours. So you are looking at about 15 hours for just the house. Most people cannot clean more than 5 hours in a day because it is so strenuous.
High cost of living areas charge $30 an hour. Low cost of living areas can charge between $5 and $10 and hour. It just depends on where you live. If I were you I would go on an hourly basis. It is impossible to bid the job with so many variables.
Let your friend know approximately how much time will be required. People can be really dense about that sort of thing, and you don't want to damage a friendship. I would allow 4 to 5 days for this job. Good luck!
I would call a cleaning company in your area. If you don't have one in the area I am sure you can go online & find one. Then charge a little less an hour than they do. Also check in your local paper under Help Offers. I am sure you will be able to get an idea of what they charge in your area.
Add your voice to the conversation. Click here to answer this question.