The advent and growing sophistication of modern cloudnative architectures has brought into question the way we design IT infrastructures. As the architectures become more complex, modeling helps employees to better understand their environment and decision makers to better grasp the "big picture". As the levels of abstraction multiply, modeling these infrastructures is becoming more difficult. This leads to incomplete, heterogeneous views difficult to reconcile. In this article, we present a collaborative approach focused on improving the accuracy of IT infrastructure modeling through the involvement of all stakeholders in the process. Our approach, applied in an incremental manner, is meant to increase confidence, accountability and knowledge of the infrastructure, by assigning responsibilities early in the process and leveraging the expertise of each stakeholder. It is suited for both a priori and a posteriori modeling at a low adoption cost, through adaptation of existing workflows and model reuse. Building collaborative models in such a way aims at bridging the gap between different areas of business expertise. As a result, we believe that our approach allows to perform analyses and use formal methods on larger scale models and cover wider technical domains.