"以茅草覆盖" can be translated into English as "covered with thatch" or "thatched over".
For example:
The roof of the cottage was covered with thatch.（小屋的屋顶以茅草覆盖。）
The old building was thatched over to protect it from the rain.（那座老建筑以茅草覆盖，以保护它免受雨淋。）