Situation : Ricardo contacts the local handyman, Simon, and discusses the removal of the existing pizza oven and the installation of a wood fired pizza oven. Simon says that he would need 24 hours to install and ensure the oven was operational. Ricardo closes his pizzeria on Mondays, so he told Simon he could have access from midnight Sunday, and all of Monday, until10 am Tuesday by which time Ricardo would need to start preparing for lunch on Tuesday.

Question : Would this promise by Simon be considered a collateral contract as it prompted the main contract? Or would it be considered an express term of the main contract?

If the answer is that the promise forms a collateral contract, would the breach of failing to perform inside of that 24 hour installation promise be a total or partial failure to perform?