It seems that when they carved out this guest unit they failed to insulate the walls. I've read up on spray foam insulation, adding drywall over existing drywall with green glue in between.

Both sound like quite a project for a lay person. Although, I do have a friend in construction who has agreed to help with another layer of drywall. I am just not sure what will add maximum sound barrier.

Do I need to drywall the closet ceiling too since it's the closet through which I hear the most noise. (Help! It's like living in the same room with the tenants in the main house).

  • A simple measure would be to fill the closet with as much loosely packed hanging clothes as possible. They will help deaden the sound, it won't cost much (maybe install an extra hangar bar), and it will alleviate storage issues elsewhere.
    – FreeMan
    Commented Jan 26, 2021 at 12:51
  • 1
    "Sound proof my guest unit carved out of main house" I have a vision of a massive block of solid wood and the OP spending years carving out a living space inside.
    – Alaska Man
    Commented Jan 26, 2021 at 18:09

3 Answers 3


There are two kinds of “sound control” problems: 1) airborne sounds, and 2) impact sounds.

  1. Airborne sounds (talking, tv, etc.) is the easiest to control.

  2. Impact sound (closing doors, heels clicking on floor from walking, etc.) is much harder to control. Impact sound travels through building materials (floor joists, wallboard, etc.) much faster and much more efficiently. In order to control impact sound, you need to isolate the surrounding material. Some of these problems are “built in” and cannot be resolved easily (or cheaply).

You indicate that most of the noise comes through the ceiling of the closet. You didn’t indicate what type of noise, (talking, TV, clicking heels walking across the floor, etc.). So, I’ll give you a few items that could help both types of problems.

First, you need to understand that all materials have a STC (sound transmission coefficient) rating. Some materials are better for air borne sound and some are better for impact sounds.

For impact sounds we try to 1) stop floor joists and underlayment from extending under a party wall, 2) provide separate party walls between rooms, and 3) stop roof joists from crossing from room to room. Obviously it’s too late for those techniques, so now you need to consider techniques for each individual problem.

For upstairs doors, I’d try: 1) provide rubber bumpers on jambs, 2) provide weatherstripping to cushion the door when closing, and 3) add closer to control speed of door closing. For clicking heels on floor, try carpet with extra thick carpet pad, etc.

If you don’t have access to the upstairs, add sound board ( fiber board) that @Hndygrl suggested on the ceiling.

I’d also seal your closet doors with weatherstripping to keep the sound in the closet.

If you have a light fixture on the ceiling, you could consider moving it to the wall and sealing up the hole in the ceiling.

Again, all materials have a STC rating and I’m sure you could Google them and their STC rating.


Sound proofing is difficult.

One extra layer of drywall and green glue will have a noticeable effect but don't expect it to be dramatic.

To give you an idea. I have a laminate with underpad, 2" concrete floor, 2x10 floor assembly, roxul batt insulation, 5/8" drywall between me and people living under me. This deadens noise such that I can't understand conversations - I can hear them they sound as if someone might be outside walking by having a conversation.

It would help if you drew a plan view of how your guest room is craved out. The best solution for this would be to build a extra wall off set from the existing one that separates the spaces, fill the wall with roxul insulation (you want mass), and drywall it. Depends if you can stand to loose 4.5" of your room.


Home Depot stocks it as "Acoustic Insulation Sound Board", store SKU 257-322. You can usually find it in the lumber or millwork (doors and windows) aisles. It is installed directly on the wall framing, then drywall is layered over it. It provides a modicum of relief from noisy neighbors and other sounds.

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