Platform B5 possesses two stepped levels with cornices and encloses the northern part of the west side of the Group B plaza. The lower level possesses a single inset stairway, while the upper terrace has two stairways flanked by balustrades, with a third balustrade dividing the two. The platform provides a broad view across the Pancaco River valley to the west. Structure B5 was built on top of an earlier construction phase, which is exposed along the upper portion of the back wall because restoration of the building only rebuilt the lower portion. It was built from stone slabs and was originally taller than the final version of the platform but was cut back to the reduced height of the new building.