Insulation Between Floors (Should I Insulate?)

 
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Old 08-15-2017, 10:46 PM   #1
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Insulation Between Floors (Should I Insulate?)


Hi eveyone. I am remodeling a small condo i just bought. It is 2 stories. Im going to run some electrical on so I removed the drywall from the ceiling on the ground floor. There was no insulation in the ceiling. My question. Is the any benefits to adding insulation before i seal it up???? Should I insulate?
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Old 08-15-2017, 11:52 PM   #2
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Re: Insulation Between Floors (Should I Insulate?)


Use Roxul... not fiberglass... 6" if it's in the budget.

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Old 08-16-2017, 02:37 AM   #3
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Re: Insulation Between Floors (Should I Insulate?)


Why wasnt there insulation there when i pulled down the rock? Are there benefits to insulating in a first floor ceiling or is it a waste of time and $ ?
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Old 08-16-2017, 07:14 AM   #4
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Re: Insulation Between Floors (Should I Insulate?)


There wasn't insulation because it's cheaper to not insulate.

As said above, regular insulation is not what you want. You need Sound Batts. Roxul does a good job. Not my favorite, to work with, but that's personal preference.

They make fiberglass sound batts. That's usually what I prefer to work with.

They also make the blue jean denim batts.

As far as sound transmittance, I think they are all about the same. In my hard of hearing opinion.

I do find customers like it, but really they only seem to notice, if they knew what it sounded like before.
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Old 08-16-2017, 08:18 AM   #5
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Re: Insulation Between Floors (Should I Insulate?)


Sounds batts don't do a lot without RC1 for the drywall to help acoustically separate it from the framing
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Old 08-16-2017, 08:27 AM   #6
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Re: Insulation Between Floors (Should I Insulate?)


Sound batts don't perform much different than regular fiberglass batts.
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Old 08-16-2017, 08:44 AM   #7
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Re: Insulation Between Floors (Should I Insulate?)


My opinion is that it would be a waste of time and money to insulate between the floors.

When you out the subfloor back in use screws.

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Old 08-16-2017, 09:46 AM   #8
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Re: Insulation Between Floors (Should I Insulate?)


It's done for sound all the time, especially shoe on a hardwood floor above.

The down side is if it gets wet, you'll have a bigger mess than if there was no insulation.
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Old 08-16-2017, 10:32 AM   #9
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Re: Insulation Between Floors (Should I Insulate?)


Always. I use fiber glass mostly. A quiet house is perceived and IS a more quality home. We also use batts in the demising interior walls, 5/8 rock on all walls and 1 3/4 solid core when its in the budget. Always 1 1/8 tng with adhesive and screws almost always over floor trusses for mechs. Seal up penetrations

We spray foam all exteriors and it took a while to get my foam guy to start doing my batts, for a while we were having to do it in house.

The floor you are doing you will hear every step and when someone flushes the toilet

We have used sound channel often like in the pic, but unless the client is going to be bumping a big ass sound system is unecessary imo. Just preference I guess


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Old 10-20-2017, 10:27 AM   #10
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Re: Insulation Between Floors (Should I Insulate?)


I like to go with insulation because it's warmer and provides a nice sound quality between floors.
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Old 10-20-2017, 12:58 PM   #11
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Re: Insulation Between Floors (Should I Insulate?)


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We spray foam all exteriors and it took a while to get my foam guy to start doing my batts, for a while we were having to do it in house.
Curios. Since you are so careful about sealing the dwelling, do you take steps to check for air exchanges with a blower door test?

If your at or below 5ACH do you install whole house ventilation?
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Old 10-24-2017, 11:15 AM   #12
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Re: Insulation Between Floors (Should I Insulate?)


I would insulate the floor. Not just for the sound reductions, it helps the heating and cooling system, and helps the exterior envelope. I have seen latex paint blister on the exterior of the home at the elevation of the floor joists. The insulation slows the convection you can get in the floor decks. It happens because it's harder to air seal the deck than an exterior wall. Even if you insulated the floor deck 4 feet off the exterior wall , and not the entire floor, it helps.
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Old 10-24-2017, 11:40 AM   #13
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Re: Insulation Between Floors (Should I Insulate?)


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Curios. Since you are so careful about sealing the dwelling, do you take steps to check for air exchanges with a blower door test?

If your at or below 5ACH do you install whole house ventilation?
I would say a blower test is exclusive to those homes where the client has expressed and is paying for that sort of perfection. Spray foam is great at dealing with 70% of the air seal, it can be better with the installer. Air sealing a home starts with the house wrap, and is a major aspect of the job, it's not just a process of the job. It's needs oversite.
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Old 10-24-2017, 11:49 AM   #14
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Re: Insulation Between Floors (Should I Insulate?)


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I would say a blower test is exclusive to those homes where the client has expressed and is paying for that sort of perfection. Spray foam is great at dealing with 70% of the air seal, it can be better with the installer. Air sealing a home starts with the house wrap, and is a major aspect of the job, it's not just a process of the job. It's needs oversite.
But a blower door test just shows how tight a home is. Newer, tighter homes really do need proper balanced air exchanges. You are right though...many won't pay for a proper erv.hrv setup to manage indoor air quality.

As far as insulating the floor cavities, I feel it is a waste if that is all you do. Soundproofing/reduction is much more involved than fiberglass insulation. Typically adding insulation just makes the person feel good that they did it but it won't really reduce the sound transmission by that much. Lots of studies out there to show STC ratings of different assemblies. At a minimum a single leg hat channel should be used in addition to the insulation to help make some difference.
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Old 10-24-2017, 12:47 PM   #15
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Re: Insulation Between Floors (Should I Insulate?)


Sound reduction, if done right costs a fortune. It's something that shouldn't be an after though of the client, it should be in the plans. There is little builders can do to have a real impact in the sound if it isn't designed by an engineer, it's applied to the structural drawings.
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Old 10-24-2017, 12:54 PM   #16
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Re: Insulation Between Floors (Should I Insulate?)


I don't know what kind of heat you have but you're going to end up with a cooler basement.
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Old 10-24-2017, 12:54 PM   #17
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Re: Insulation Between Floors (Should I Insulate?)


I'm in climate zone 3, by far the toughest region in the United States to build in for those conditions, sealing that tight is mandated. Yes fresh air exchange or ERV are required. We do it different on different applications

On my personal home I did not follow this, I just spray foam the envelope and ran one fresh air duct into the AC. With a manual damper. I have two small children and go in and outside all the time and if I need fresh air will open the windows. I think it is retarded to have a fan sucking hot air into a house that I'm trying to cool. Like with a Whole House Fan. There are other ways to do it, unfortunately the lawmakers did not consult me.

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Old 10-24-2017, 01:01 PM   #18
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Re: Insulation Between Floors (Should I Insulate?)


Quote:
Originally Posted by overanalyze View Post
But a blower door test just shows how tight a home is. Newer, tighter homes really do need proper balanced air exchanges. You are right though...many won't pay for a proper erv.hrv setup to manage indoor air quality.

As far as insulating the floor cavities, I feel it is a waste if that is all you do. Soundproofing/reduction is much more involved than fiberglass insulation. Typically adding insulation just makes the person feel good that they did it but it won't really reduce the sound transmission by that much. Lots of studies out there to show STC ratings of different assemblies. At a minimum a single leg hat channel should be used in addition to the insulation to help make some difference.
In my opinion it is reduced by at least 75% just putting bats between the floors. I can tell a noticeable difference when my guys are walking on a second floor of a remodel where they did not insulate between the floors, in comparison to when they walk on the second floor of a home we built and insulated between the floors. We also use inch and an eighth plywood and floor trusses, so that may be a big part of it as well

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Old 10-24-2017, 01:50 PM   #19
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Re: Insulation Between Floors (Should I Insulate?)


New construction or 100 yo house - insulation between floors and bath walls reduces sound transmission. At least you won't be able to tell which side of the paper someone used to wipe.

Moisture control is pretty interesting, but as I pointed out to Struble a few years ago (and he took the wrong way), people have been successfully dealing with air quality and moisture in chicken coops for a long time.
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Old 10-24-2017, 01:56 PM   #20
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Re: Insulation Between Floors (Should I Insulate?)


In climate zone 3 you are at 3 air changes per hour, which is a very tight house. I am in process of learning as much as I can about tight houses, air quality, mold control, humidity control. We definitely use dual or 5-speed air conditioning systems now to make sure the humidity is under control and we throw a duct into the attic to cool it off to keep mold from growing. There have been lots and lots of cases of poorly-built houses under these conditions, too tight and oversized air conditioning units that are not built with multi-speed air conditioning to get the humidity out.

I have always believed a house needs to breathe, nowadays I can't allow that. We had great success spray foaming all of our walls I have always believed a house needs to breathe, nowadays I can't allow that. We had great success spray foaming all of our walls with open cell spray foam and putting better than R38 blow in on the ceilings. Great success, and we were still able to put in venting in the Attic.

With closed-cell insulation I believe I will pass my door blower test on the houses we are on now without sheetrock. We will see you anyway because I'm going to try. I plan on experimenting with some different types of insulation, and hybrid of different installations.

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