Closed Cell Spray Foam and a Really Loud Roof
Reader JAMES in BRUSHTON writes:
“I have a pole barn with metal roof with 4.5 ” closed cell spray foam on underside of 2×4 strapping but it’s REALLY loud when it rains how can I make it quiet inside without causing a moisture/condensation trap.”
You can quiet your pole barn inside by installing a dropped ceiling with an air gap or adding an interior layer of sound absorbing material (like acoustic panels or mass-loaded vinyl) beneath your existing foam.
Even though you have 4-1/2 inches of closed-cell spray foam, it is rigid and dense. Because it is stuck directly to your building’s steel roofing, it can still vibrate when heavy rain hits, passing noise straight in.
Build a finished ceiling with an air gap. Hang a drywall or drop ceiling (acoustical tile) suspended a few inches below spray foam. Leaving an empty air space between foam and your new ceiling breaks vibration path and traps sound waves.
Fasten heavy mass-loaded vinyl (MLV) sheets directly to spray foam surface. MLV is a dense, flexible barrier adding weight to stop panel movement and block sound transmission.
Hang acoustic panels. Attach sound-absorbing fiberglass panels or mineral wool boards to ceiling surface. These panels will not stop vibration, but they soak up echos and reverberation inside building, making rain sound much softer and less sharp.
Install strapping and a secondary interior finish. Screw wood or metal furring strips into your framing, then attach plywood, OSB, or sheet metal panels over them, This creates a decoupled layer, interrupting sound waves.
We also know clients who have had open cell spray foam applied over closed cell. Open cell foam is soft, porous and flexible. Its interconnected structure traps sound waves and converts their energy into heat, making it much better at absorbing sound and reducing echos.
