BASEMENT FINISHING COURSE VIDEO: Boosting Sound Resistance of Basement Ceilings

This video is all about the different features that you could build into the ceiling of your basement to improve the sound resistance

So this is something that will help keep the sound generated in the basement downstairs and also help stop the sound from above coming downstairs

When it comes to soundproofing, it's really a series of choices of features of features that you can apply

and more or fewer of them. It really depends. So what we've got here, these are the floor joists

They exist in your basement now. And then this is the sub floor here. So people walk up on top of that, on top of the finished floor that's on top of that

And down here we have the basement space. So a few things are going on here

If you only wanted to do one thing to improve the sound resistance

sound proofness of your basement, it would be to install this item here

This is called Resilient Channel, and it's a sheet metal product that's designed to

reduce, greatly reduce, the contact between the drywall of a ceiling and, in this case

the floor joists up above it. So the resilient channel is held by these clips

The clips are firmly fastened to the floor joists with screws, typically

And the clips hold the resilient channel. Now, the drywall does not fasten directly to the floor joists at all

The screws that hold this first layer of drywall go into the resilient channel

They make their own hole in that channel and they thread into that channel and that what holds the screws so there really is very little contact between the drywall and the joists and that what holds the screws So there really is very little contact between the drywall and the joists and that what helps greatly to reduce sound transmission

So as I said, if you just wanted to do one thing, that would be the thing to do

That said, you really should consider adding some kind of fiber-based insulation between the joists

Now, that can be fiberglass or rock wool. I personally enjoy working with rock wool much more

I find the bats are easier to cut than a fiberglass. They're less dusty

They're more rigid. They're less likely to absorb water. I've tested all this and come to the conclusion that rock wool is a superior product

So I would recommend using that. In order for the bats to stay in place, you're going to have to add these one and a half inch by one and a half inch cleats

They just screw to the side of the joists and they create a little bit of a ledge to keep the insulation up

Now, without this, the insulation could settle down over time. It's going to sit in between the joists by friction fine now, but with the various vibrations and things of the floor from people walking

on it. It will settle down and you really do want to have some kind of an airspace here if you can

So these cleats provide that. You can just use deck screws to fasten them to the sides of the

joists. And you're going to get a noticeable reduction in sound transmission. Now if you want more

sound resistance, then would be provided by this single layer of drywall, the resilient channel

and some insulation. Then the next thing to come down, consider would be adding a second layer of drywall to the ceiling side of things

Now I should say that I specified 5 eighths inch thick drywall here That works substantially better than half inch drywall which is much more standard In addition to that I really like 5 fire code drywall

because that includes reinforcing glass fibers right in the gypsum core, and that adds a lot of strength to the drywall

If you're one of these people that doesn't like how flimsy half-inch drywall is

then 5-8's fire code is for you. It's required in commercial buildings because of its fire-resist

but it's just plain more substantial in a home situation too. Now, what I've got here, what I'm specifying here

is a unique product called green glue. It's an acoustic product. It comes in caulking tubes

and you lay down a zigzag pattern of the green glue between the layers of drywall

and it further enhances the sound resistance. It takes about 30 days for the green glue to become fully

effective and even though it's called green glue it's not actually a structural adhesive so you still have to fasten

this second layer of drywall with all the usual number of drywall screws going up

into the resilient channel not into these cleats or the joists and if you do that you're going to

gain even more sound resistance if you want to go one step

further then you should consider adding a couple of layers of 5 eighths drywall

between the joists, up fastened underneath to the subfloor. This is something you need to do right up front

You can't decide to do it later. And here we've got one layer of green glue here, another layer of green glue there

and it's held up to the subfloor with screws. You're going to have to choose screw length properly

You don't want them to be too long and have them go right through the subfloor, but then again you don't want them to be too short and not provide enough holding power

The thing about soundproofing is that mass matters The more mass you can get between you can put between you and the noise the better the soundproofing effect is going to be all else being equal

Now, there is one other thing, and it can happen on top of the subfloor

If you will be changing the finished flooring in the above ground section of your house

then you really should consider adding a layer of rubber acoustic underlay on top of the subfloor

underneath your new finished floor. This is a product that's made from recycled tires

It's a little bit less than a quarter of an inch thick, at least the stuff I've seen and used. And it greatly reduces the transmission of low and medium frequency noises

through the floor. So this would be the sound of people walking around, people moving furniture

someone climbing out of bed in the morning and thumping onto the floor. All of this stuff that I've told you about so far

all of the drywall and the green glue and the resilient channel

It's pretty good at blocking medium and high frequency sounds, but it's not going to do as much as you think for the low frequency footfall sounds

The rubber layer will. That's really what it's meant to do. And if you're going to be putting a new finish floor on upstairs

then adding a layer of that rubber is certainly going to help

create a floor structure, a floor system that isolates the basement and the upstairs as much as possible

And that's a very important thing because the size of a house is really about how, at least in part

about how we perceive the presence of others around us. So your home and your finished basement is going to seem a lot larger if you don't hear things going on upstairs and vice versa

So this is the recipe for a seriously sound resistant ceiling in your basement

And I think you'll find all these details make a big difference that's worthwhile