We have a few rentals in our town (Tacoma, WA). 

There is a good amount of square footage and it is a single family house.

Build the most square footage you can in that footprint (deepest and tallest). 

paid $53,000 Did all the work and made $100,000 7 years ago.I bought it right 2600 square feet. 10 foot ceilings.original flooring and trim with doors.good roof and furnace. need a great agent and contractor both to make real money. 

We are currently designing a 2 bed 1 bath on a slab 720 square feet to be modern like this and it's extremely compact and will be on a slab. small homes in our market sell at a premium close to $300 per square foot.

This is a house that has additional square ft added on, so they listed that as the reason for marking the question as positive, as new foundation and support was added for the additional sqft.My question is: Is it a standard practice to check this box as "yes" in the disclosure when additional square feet has been added on to the property?

For this example we will use 70% For this formula you will need to know the following:ARV=After Repair Value ( How much will the house will sell for after making all the repairs needed)Repair Estimate - (Send me a message and I can send you a list I got from my mentorship class for ball park estimates based on square footage and depending if you need cosmetic repairs, avarage repairs or Extreme repairs)Your Assigment FeeARVx.70 - Repairs - Your Assignment FEE = Max OfferExample$200,000 x .70 = $140,000 - $30,000 (repairs) - $10,000 (your profit) = $100,000 (offer)Your potential profit is $10,000 I hope this formula helps you make offers that will make sense for all involved in the transaction.Happy Wholesaling,Lily Rodriguez - Investor friendly Broker

Its like 55-60% Commercial....but there is a lot of space to increase the residential  square footage  (such as a laundry room).

There's a couple things - you can get bridge funding now or some type of private money bridge/construction loan that will give you acquisition funds, so that you can acquire said building and then take the time to get your permitting squared, and then roll into construction portion once ready. 

Less debt, more cash and a better credit score have a very high success rate. when I did my sub to in earnest was pre 2007 when it was legal to rescue someone from foreclosure and then rent back to them.. it is no longer legal in OR or WA to do that..