Capturing and using design rationale is becoming a hot topic for software architects, as architectural design decisions are now considered first class entities that should be recorded and documented explicitly. Capturing such architecture knowledge has been underestimated for several years as architects have been only focused on documenting their architectures and neglecting the rationale that led to them. The importance of recording design rationale becomes enormous for maintenance and evolution activities, as design decisions can be replayed in order to avoid highly cost architecture recovery processes. Hence, in this work we describe how architecture design decisions can be captured and documented with specific tool support. We also provide effort estimation in capturing such knowledge and we compare this with architecture modeling efforts in order to analyze the viability of knowledge capturing strategies.