How to expert all levels !!!!!
I have completed all the levels on expert with no cheats (if there is one)or changing files.
When i first played the game I thought that it must be impossible to complete the levels on expert as I was just barely making it with regular time. Then I got the tip that turned it all around !!!
You must always flip (sell) your first house you build.
In the later levels I build a sawmill first thing - dont build a house
Then I build the workshop. With these two things everything is cheaper.
I buy 75k of materials while waiting for my workshop.
When the workshop is complete I get 2 workers and then I am ready to rock.
I dont build the bank at this point as you will see why.
I build a mansion on a lot. When it is done I upgrade immediately. Wait for it to pay then upgrade again.
When done, sell the house (dont worry you can buy it back later when you are flush with cash)
I dont upgrade past 2 stars to flip a house for 2 reasons. it costs more to upgrade to the 3rd star then what I will get back in profit and it takes more time at this crucial juncture.
You now have close to $600,000 to get the money engine running.
If you are in levels where you can get the castle, get the extra workers needed, buy as much materials as you can then build your castle. If not build your second mansion. Upgrade to 2 stars then sell this house too. While you are buidling this house get yourself more workers and materials. This will really set you up.
You dont have to worry about building the bank right away as you dont have the houses on hand long enough for the tax man to come. I usually build the bank after my 4th house.
With this much money on hand you can do anything. I build houses and upgrade as high as I can. When other lots or houses come up for sale I can easily buy them, demolish them and build a bigger house.
While you are building, keep buying materials and workers, you dont want to ever be out of them. If you are waiting, you are losing money. I usually finish the levels with close to 30 workers especially the later levels when I am buidling castles.
In the later levels when you need the large amount of cash to finish the level I start selling my 4 star homes with about 2 minutes to go before the expert mark (you dont need them for the winning conditions) I start with the ones I havent inspected yet.

Here are some key tips to keep in mind:
- Always flip your first house, I recommend flipping the second one too, really gets you started fast.
- during later levels build the sawmill and workshop before you start building your houses
- dont stop buying materials and workers
- dont always wait for rent before upgrading, time is of the essence, if your house is making you 60,000 at four stars you will make up the 30,000 you lost pretty quick.
- in a pinch, sell a house, it will come up for sale later and you will be in a better position then.
- Dont worry about inspecting homes until they are fully upgraded. They dont break down if you constantly are upgrading them.
-If you buy a house demolish it and build the biggest house you can. A bigger house upgraded to 3 or 4 stars will pay alot more than the smaller house.

With these tips you should be able to expert all levels like I did.
Good luck