A bid proposal is a document used to outline a business's products or services when applying for a contract. Each bid must be enclosed in a sealed envelope which shall be clearly labeled with the words "Bid.Our construction bidding guide will take some of the mystery out of the process. Construction Bidding Process. In this article, learn how to customize a construction proposal template that you can use when participating in bids. All sealed bids must be received on or before Friday, October 19, 2018 a.m. , Palm Beach County local time. • Answers to Questions posted on Palm Beach.