NCIDQ Interior Design Professional Exam (IDPX) Practice Exam 2026 - Free Interior Design Practice Questions and Study Guide

The correct answer is the change order, as this is the formal document used in construction and design projects to authorize modifications to the original contract scope. When a specified tile is out of stock, a change order is necessary to amend the plans and specifications regarding the materials being used. This document outlines the changes, including any adjustments to the costs and timelines associated with the substitution of tile.

The reason why the change order is crucial in this situation is that it legally modifies the contract between the designer and the client or contractor, ensuring that all parties are informed of the new materials and associated costs. This formal authorization helps prevent disputes and keeps the project on track.

In contrast, a bulletin might communicate updates or clarifications but does not constitute an official modification of the contract. A contract amendment typically involves more significant changes to the legal agreement itself rather than minor adjustments like material substitutions. Addenda are usually issued during the bidding process to clarify or modify contract documents but do not serve the same purpose as a change order once a project is underway.