So you still have to spend the time to run all the comps yourself and validate the property with the construction team. 

My first SFH renovation ended up taking 1 year because the inspector missed a ton of things and about a $50,000 cost.

Take those plans to the county you intend to assemble the modular home and ask them if any additional construction would be needed to meet current building codes. 

I've read online that you can get an FHA construction loan, but I can't seem to find much information or others with prior experience.Any thoughts or advice?

I’ve debated doing a smaller flip as I have construction experience.

Estimating construction and remodeling has been around a long time, people who do this are called estimators.There's books, software and even courses on estimating.

Cosmetic renovations are easier to estimate rehab cost and are still considered "turn-key" to sellers.Happy to connect about any renovation or construction needs.

For all of our clients we have everything from contractors, maintenance, lenders, property managers, and inspectors we recommend and work with everyday that can help get the information you need to make an informed decision before buying a property and help manage the property. 

How quickly are you seeing inspectors come out once RFTA is approved?

Working with Inspectors: How easy is it to work with inspectors in Oakland?