Yours will vary depending on the site soil conditions and legal requirements in your state.We removed the old trailers and brought in newer ones.

Our clay soil moves all over the place and the amount of settling and resulting repair can be extreme. 

If they weren't renailed properly and sealed after the new roof....melting snow could be the source....it will melt against the exhaust pipe and run underneath.  

I Am trying to get homes underneath contract but is it better to find buyers first rather getting a home underneath contract.

They are typically used in instances where fitting a trap underneath the toilet is either not feasible or cost effective.  

Those are some pretty serious issues (foundation, sounds like, combined with the nearby lake and septic issues sounds like there may be fundamental soil issues.)

He said he could take a look with the camera and see how damage/corroded they are and take it from there..Also, I asked him about the base pipes underneath the house and he said most of the time there shouldn't be problem with them?

Then you have to deal with environmental issues, soil issues, etc., which can impact buildability (is that a word?

With this disclosure, you may have to undertake a Phase I Environmental Assessment - your lender or insurer may insist on it.We had a very similar deal on a multi-family a year ago - when the Phase I and some soil sampling came back strongly indicating remediation, we - and our lender - insisted on placing a substantial portion of the purchase price (30%) in escrow to cover remediation costs.

It seemed like a great deal, and there's only a few lots left not built out.In doing our due diligence, we found out that since the original development, the City has decided the soils in the area are going to require more stabilization, and aren't even sure what they will require.