Yapp is more familiar on the other side of the scrum at loosehead for region and country but he has switched over and is relishing the challenge of overcoming the nuances of the new surroundings.
"There's a hell of a lot of difference between the two positions," he said from the Wales base in Chicago. "Very few people apart from front row forwards know anything about scrummaging and think it's all the same but it's two totally different positions.
"As a tight head you are more susceptible to being attacked rather than at loosehead because the loose head always attacks the tight head so you have got to be more of an anchor. Most scrums go back on the tight head so it is a lot different. I've been playing loose head for a few years so it's good to have a new challenge. It give you something to work on and think about and I'm enjoying it."