How to Soundproof a Furnace Closet

The door is typically the weakest point in a furnace closet. Gaps around the frame allow airborne sound to escape. If your closet has a hollow core door, you must upgrade to a solid core door. Hollow doors are not good for soundproofing.

Install the Sound Lock adjustable door soundproofing kit to seal the perimeter and bottom of your door. This is the best method for soundproofing a door because it creates an airtight barrier that prevents sound leaks. Proper door sealing alone can significantly reduce furnace noise, and that’s what we’re after.

This is almost always the best course of action as it requires the least effort and yields great results. After sealing the door, reduce echo and mechanical reflections inside the closet. Install CelluZorbe panels on the interior walls to absorb sound and reduce noise by up to 50%. This is about reducing the overall noise inside the closet rather than physically blocking sound from escaping.

If noise is still noticeable in adjacent rooms, you will need to do construction to soundproof the walls. If you are building a new wall, install mass loaded vinyl to the studs and then seal it in with 5/8" drywall and acoustical sealant around the perimeter. If you don’t want to remove drywall, use Green Glue to install a new 5/8" thick drywall layer over the existing wall. Bear in mind that furnace closets are often tight on space, so plan accordingly.

For additional wall soundproofing strategies, see soundproofing materials.

Impact noise can travel through the floor structure and the best cure is to isolate the furnace from the floor. The Stomp Mat works great for this. Improving the floor assembly can also reduce impact noise heard in the rooms below but it will require construction so you should read up on how to soundproof floor assemblies.