Seating Riser Construction

(Originally published June 3, 2008)

Construction has recommenced! This past week I finished the seating riser for the second row of seats. It's framed up from 2x8s on 12 inch spacing. Between the riser framing and the floor is a layer of 30lbs roofing paper to eliminate creeks and help mitigate sound transfer through the floor.

The cavities in the riser were filled with R-30 fiberglass insulation to prevent it from resonating the deep bass frequencies from the sub-woofer. The riser will also form a sort of bass trap to absorb extra low frequencies in the room.

The decking is two layers of 3/4 inch plywood, glued and screwed down to the riser joists. In between the two layers of ply is a product called Green Glue which reduces sound transfer through the floor.

1/4 inch wide by 26 inch long slots were routed all t he wall through the decking, one slot for each insulation filled cavity. This turns the riser into a bass trap to absorb some of the unwanted low frequency sound waves.