Estoppel certificates apply only to commercial real estate?

[Larry Bowers]

I read about estoppel certificates and get the concept. Would it be out of line to request them as a buyer in a residential (fourplex or less property), or is that overkill and/or just not done?

[Joel Owens]

Estoppel you are verifying what is in the lease is accurate and that there are no written or spoken agreements otherwise. 

Definitely you want to get it and notarized. That way seller cannot forge and say tenant signed it and tenant cannot claim they didn't sign it as notary witnessed it after being provided valid ID of person signing.  

It's not absolute just one mechanism among many with due diligence and a purchase and sale contract to try and keep the seller honest.