Im assuming they are coming from basement and i do notice the back end of basment wall has an opening where they built an extension so assuming i would need to close this off and seal up all cracks/openings to ensure this does not happen again.

Expect the unexpected, but this where you seal the deal, sir. 

Use hard money to seal the deal the refi a few months after you move in.

One company said to do some mastic and foil tape sealing in the ducts in the basement to fix.

It really seals the nicotine in.

Thanks Word of the wise to others reading this- always always check with the AHJ/Building Dept. on requirements for Architect/Engineer to sign/seal documents. 

If something is selected as harmful and not moral by society to a level it should not be, like say Baby Seal Slippers, society will vote with it's commerce and that item will not exist. 

. $75.00Bedroom needs new hardwired smoke detector with 10 year sealed battery. $60.00Back bedroom 11‘4“ by 12‘6“ Mine are pulling up to our room. $45.00Paint entire room walls ceiling trim windowsills and doors. $250.00Remove and replace smoke detector with new hardwired 10 year sealed battery. $60.00BasementFront room 11‘ x 12‘ Wipe down walls and spot paint as needed. $75.00Middle room/hallway Remove and replace combo detector for 10 year sealed battery. $100.00Wipe down walls and light touchup on doors walls trim. $125.00Hall and stairs closet needs to be scraped and painted due to water/flaking paint throughout closet. $125.00Bathroom 5‘ x 7‘ no pop up on pedestal sink. $125.00Light touch up throughout walls trim sills and ceiling. $100.00Laundry room 7‘ x 7‘ Water damage on ceiling and walls.

We also post the notice is a sealed envelope with the tenant's name/confidential on their door and take a photo of it as proof. 

Not a chance in hell.......I see 2 options......(1) Belt sand it down, re-stain and seal it...... charge a reasonable fee for that..... probably $300-500 max(2) Charge them $300-500 for the damage, but replace all of the counters with better materials and eat the cost now, but prevent the issue again in the future..... horrible counter tops for the main sectio in a kitchen..