Soundproofing can lights in our basement Airbnb

The sound transmission between our apartment and basement Airbnb has bothered me since we moved into our first triplex. I added carpets and drapes to our apartment, and I am always mindful to be quiet when we host guests. But I’ve never been intentional about soundproofing the basement. Since we are considering a move and our future tenants may not be as considerate, now is the time to reduce the noise between apartments.

The lower guests/tenants can always expect a certain amount of impact noise; although we plan to lay underlayment and new laminate over our hardwoods when we leave, we never intend to get carpet. What I want to avoid is airborne noise – our toddler squealing, our bird shrieking, even our conversations. Because I will not rip out our ceilings and install insulation, my tools are limited. So I am going to focus my efforts on the areas where the most noise transfers.

Testing for noise

I started by identifying where the noise was coming from. When you are in the Airbnb, it’s pretty clear that the noise is coming from a few key areas:

• Recessed can lights: There are eight can lights throughout the apartment, and you can hear that they leak sound when standing underneath.
• Furnace closet: Our furnace is in a storage closet in the Airbnb… and the sound reverberates through the HVAC to the furnace. Additionally, the insulation between floors is not great in that closet – the subfloor was exposed when we purchased the house, so we screwed in some drywall with insulation. We never taped and mudded the drywall. Sealing this closet would go a long way.
• Bedroom closet: The HVAC passes from the storage/furnace closet through to the bedroom closet, so there is noticeable sound coming from there. Besides the closet, the bedroom stays pretty quiet.

I measured the sound using a decibel meter and recorded the initial measurements. I’ll check again when I’m done to see what was most impactful.

I couldn’t tackle this entire project at once because 1. we are trying to finish all our projects at Union Hill and this would be a distraction and 2. we have guests coming. The can lights required the least effort, so I decided to start there.

Soundproofing the can lights

I recognize that the best way to sound proof can lights is to thoroughly insulate the ceiling and put the light housing with these covers. However, I can’t do that for the reasons listed above. Since I am not going to rip out the ceiling, I had to get creative.

We replaced traditional bulbs with LED retrofit inserts when we first set up the Airbnb, and the inserts never quite fit right. So there was a lot I could do to prevent sound by closing the gap with the ceiling.

Here is what I used:

• Putty: These are typically used to seal electrical boxes, so I knew they were fire safe and used with wiring. Since the LED inserts don’t get hot, I didn’t have to worry as much about what was behind them.
• Green glue caulk: I decided to get soundproofing caulk to seal the gap between the light and the ceiling.

I wrapped the putty sheets around the back of the lights and wires, sealing all areas that would not be caulked. I then partially placed the lights back in the cans, then I caulked the perimeter.

One thing I had not considered – or conveniently forgot after our last experience caulking can lights – is gravity. The putty went on easy, but it added weight and made the gap worse between the light and the ceiling. Thank goodness this is a basement with lower ceilings, because I had to rig a few systems to push the lights up against the ceiling while the caulk dried.

Results

These extra steps did seem like they made a difference – there is no longer a small jump on my decibel meter when I pass under the lights. I don’t really know what made the difference… could I have just done the caulk? Or was it the combination of caulk and putty that did the trick? And I will not be able to make a huge difference until I address the two other problem areas. I will say this – the can lights look much better now that they are sealed with caulk. I should have done that years ago!