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Old 04-18-2018, 07:10 PM   #1
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Basement Insulation - I Dare Ask?


I've looked through this thread and many others and it's amazing on how many conflicting viewpoints I get when it comes to basement insulation! So, I'm sorry if I'm being repetitive. I figured I'd throw out my situation for advice. I can't afford closed cell spray foam, so I'm looking for further options. I wrote some info below and included some pictures:

1) Live in the Midwest.
2) Basement exterior walls are roughly half concrete foundation (below grade) while the top half is brick (above grade).
3) Brick is set back about an inch or two, so there's a little ledge on the foundation. See the pictures.
4) I have drain tile around the perimeter of my basement. Installed by PermaSeal.
5) There's 20 mil wrap (CleanSpace: 20 mil polyethylene vapor barrier) over the concrete foundation. So, any water coming from the foundation should drain down into the drain tile.
6) I'll be framing out with 2x4s.

I'm hoping to use batt insulation and have a few questions.

A) Should it be faced or not faced? I've had two contractors over. One said faced and the other said unfaced because I already have that vapor barrier against the concrete.

B) Should I put more vapor barrier over the brick? I figured I'd have batts to fit my 2x4 framing, so it would not be up against the brick since the brick is set back an inch or two from the foundation.

C) Should I still frame an inch away from the foundation even those there's already that thick vapor barrier on the foundation?

Check out the pictures. Thanks in advance!
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Basement Insulation - I Dare Ask?-img_2173.jpg   Basement Insulation - I Dare Ask?-img_2175.jpg   Basement Insulation - I Dare Ask?-img_2176.jpg  
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Old 04-18-2018, 07:19 PM   #2
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Re: Basement Insulation - I Dare Ask?


Let's discuss the water entering the cellar. That should be stopped from the outside first. The way to do that is to seal the foundation down to the footing w/ a membrane. Is there any reason why that can't be done?
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Old 04-18-2018, 07:44 PM   #3
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Re: Basement Insulation - I Dare Ask?


I've demoed a lot of basements over the years. I wouldn't use fiberglass in a basement. If it gets a little damp, which seems inevitable, it gets nasty real quick. Personally, I'd figure out a way to use rigid.
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Old 04-18-2018, 07:55 PM   #4
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Re: Basement Insulation - I Dare Ask?


Basements deal with two types of moisture, vapor, and liquid water. The liquid water can arrive from outside or from condensation on the inside. The vapor can also pass through the walls from either inside or outside.

You mention "4) I have drain tile around the perimeter of my basement. Installed by PermaSeal." Which doesn't sound good, in other words not a perfectly dry basement to start with.

With the insulation on the inside the concrete or brick will be very cold, likely below the dew point for inside air. Using permeable insulation (fiberglass) means inside air will be able to reach the cold surface and deposit moisture.

Leaving an air gap between the insulated wall creates a potential for convection where slightly warmer air from the lower portion of the foundation will carry moisture up to the colder upper portion.

It is very difficult to offer advice for a work in progress basement when that work has already headed in perhaps the wrong direction. Moisture and water problems are best addressed from outside as Guap0 suggested. On the inside a layer of rigid foam board will both add r-value and keep the inside surface above the dew point, but that may no longer be possible.

If you haven't run into the link below it offers a good perspective on basements.
https://buildingscience.com/document...ts?full_view=1

Bud
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Old 04-18-2018, 08:21 PM   #5
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Re: Basement Insulation - I Dare Ask?


We build 1" away from concrete for 2 reasons, keep wood away from concrete and to stay away from bulges that we get with the type of forms we use. You have the deluxe water management system for what could be a leaky basement.
You don't want to pinch the plastic against the foundation so I would still build a little away with a sill gasket under the lower plate.
The top plate want to close the gap between this wall and the floor area as fire stop.
We often just start with a 2x6 for the top plate and level down from there to place the lower plate. We usually go to the sill plate above the foundation. Can's see what you have with pipes and things. You could start with a 2x3 and then a 2x6 against the brick with a caulk of some kind that would stop air flow and protect the wood from toughing brick.
We use bat insulation in a 2x4 wall. We add a vapour barrier under the drywall. The poly against your wall does not count as it is a totally different thing. It is water management and if water does seep in there we could expect the surface to be cool.
Vapour barrier is to stop warm moist air from getting to anything cool where the moisture will condense. There is an argument about vapour barrier but there is no reason for your wall to get wet from the outside and it will not breath to the outside.
So it is all about moist air from the inside. If you go for it the paper faces is a joke as it will never seal all so your choice should be plain or poly covered With sealed outlets and everything.
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Old 04-18-2018, 08:23 PM   #6
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Re: Basement Insulation - I Dare Ask?


Quote:
Originally Posted by Bud9051 View Post
Basements deal with two types of moisture, vapor, and liquid water. The liquid water can arrive from outside or from condensation on the inside. The vapor can also pass through the walls from either inside or outside.

You mention "4) I have drain tile around the perimeter of my basement. Installed by PermaSeal." Which doesn't sound good, in other words not a perfectly dry basement to start with.

With the insulation on the inside the concrete or brick will be very cold, likely below the dew point for inside air. Using permeable insulation (fiberglass) means inside air will be able to reach the cold surface and deposit moisture.

Leaving an air gap between the insulated wall creates a potential for convection where slightly warmer air from the lower portion of the foundation will carry moisture up to the colder upper portion.

It is very difficult to offer advice for a work in progress basement when that work has already headed in perhaps the wrong direction. Moisture and water problems are best addressed from outside as Guap0 suggested. On the inside a layer of rigid foam board will both add r-value and keep the inside surface above the dew point, but that may no longer be possible.

If you haven't run into the link below it offers a good perspective on basements.
https://buildingscience.com/document...ts?full_view=1

Bud
Bud that is the best water management you can get and it deals with outside water so you count it as the driest basement.
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Old 04-18-2018, 08:25 PM   #7
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Re: Basement Insulation - I Dare Ask?


Thanks for the info. I've read that article and it provides lots of valuable information and really defines the perfect setup.

Drain Tile: The previous owners had some water issues with their plumbing. That's why they had the drain tile installed. Since then, I've had an overhead plumbing setup put in. The only water/moisture issues I'll have to deal with is anything that seaps in from the brick or foundation, maybe condensation.

Here's where I'm still confused. I understand that some warm air can still go escape through the drywall, then through the fiberglass batt, and then hit the cold foundation, but...won't the thick vapor barrier over the foundation keep the outside moisture away from the fiberglass? Wouldn't any condensation (or any type of moisture) formed just roll down to the drain tile between he foundation and vapor barrier?
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Old 04-18-2018, 08:31 PM   #8
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Re: Basement Insulation - I Dare Ask?


Quote:
Originally Posted by TimRemo View Post
Thanks for the info. I've read that article and it provides lots of valuable information and really defines the perfect setup.

Drain Tile: The previous owners had some water issues with their plumbing. That's why they had the drain tile installed. Since then, I've had an overhead plumbing setup put in. The only water/moisture issues I'll have to deal with is anything that seaps in from the brick or foundation, maybe condensation.

Here's where I'm still confused. I understand that some warm air can still go escape through the drywall, then through the fiberglass batt, and then hit the cold foundation, but...won't the thick vapor barrier over the foundation keep the outside moisture away from the fiberglass? Wouldn't any condensation (or any type of moisture) formed just roll down to the drain tile between he foundation and vapor barrier?
Your poly should be sealed to the concrete so moisture on the inside the home does not go into that system.
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Old 04-18-2018, 08:41 PM   #9
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Re: Basement Insulation - I Dare Ask?


Fun isn't it Tim. You mentioned running into a variety of opinions and with basements that is certainly the case. Part of the reason is basements come in many forms and often what works in many locations is assumed to work in all. In reality guidance comes with a built in amount of failures. Better guidance equates to fewer failures but not zero. It leaves the home owner with the task of deciding where their basement falls within the mix and how much of a risk they are willing to accept.

One of the concepts that many experts will offer is to omit all vapor barriers and allow any moisture to dry to the inside. That assumes the amount will be very small and easily handled by the heat or cooling inside. If moisture levels are higher the risk will be higher.

You asked "Wouldn't any condensation (or any type of moisture) formed just roll down to the drain tile between he foundation and vapor barrier?" Moisture on the inside of the vapor barrier would be in contact with the insulation and fiberglass has a mixed history. Might consider Roxul.

Have you verified your local code requirements for basement insulation?
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Old 04-18-2018, 08:43 PM   #10
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Re: Basement Insulation - I Dare Ask?


Nealtw: Thanks for the replies. From the foundation down to the floor, the poly is completely sealed. It's only opened at the point where the brick starts up from the foundation.

I had an insulation contractor check it out. His suggestion was to extend that barrier to the top of the brick by overlapping (and taping) more poly so that the barrier is floor to ceiling. He said he'd put in R-19 unfaced batts if there was enough room...assuming it'd be framed an inch or so from the foundation like you said you do. He also said something about foil faced between the ceiling joists, but I can't remember his exact comment.
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Old 04-18-2018, 09:00 PM   #11
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Re: Basement Insulation - I Dare Ask?


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Originally Posted by Bud9051 View Post
Fun isn't it Tim. You mentioned running into a variety of opinions and with basements that is certainly the case. Part of the reason is basements come in many forms and often what works in many locations is assumed to work in all. In reality guidance comes with a built in amount of failures. Better guidance equates to fewer failures but not zero. It leaves the home owner with the task of deciding where their basement falls within the mix and how much of a risk they are willing to accept.

One of the concepts that many experts will offer is to omit all vapor barriers and allow any moisture to dry to the inside. That assumes the amount will be very small and easily handled by the heat or cooling inside. If moisture levels are higher the risk will be higher.

You asked "Wouldn't any condensation (or any type of moisture) formed just roll down to the drain tile between he foundation and vapor barrier?" Moisture on the inside of the vapor barrier would be in contact with the insulation and fiberglass has a mixed history. Might consider Roxul.

Have you verified your local code requirements for basement insulation?
Bud
Bud9051: Haha. SO much fun. My inspector said I just need to make sure I meet the correct R value. He's not very picky.

I agree with you. Basements are tricky and we'll get various results in various climates.

Can I just used faced fiberglass insulation and hope for the best? (Maybe that's what you're saying). The faced insulation, in theory, would keep the moisture on the drywall side of the wall. Then, my current poly barrier on the foundation would keep moisture on the foundation side of the barrier? There'd still be a little gap between the insulation and foundation vapor barrier for air to flow. Final thoughts?
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Old 04-18-2018, 09:11 PM   #12
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Re: Basement Insulation - I Dare Ask?


2 vapor barriers should always be avoided as any moisture that gets in will have a difficult time getting out.

Trapping the moisture against the foundation isn't all that bad as it has a direction to drain and concrete loves moisture. You just want to be sure it doesn't find a path through to the insulation and drywall side.

All you have mentioned for location is Midwest so I'll post the 09 map for insulation guidance. Your location may have moved to 2012, 2015, or 2018 codes but most are still same or close to the 09.
https://energycode.pnl.gov/EnergyCodeReqs/

Insulation that fits 2x4 walls will typically not meet most cold climate codes.

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Old 04-18-2018, 09:25 PM   #13
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Re: Basement Insulation - I Dare Ask?


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Originally Posted by TimRemo View Post
Nealtw: Thanks for the replies. From the foundation down to the floor, the poly is completely sealed. It's only opened at the point where the brick starts up from the foundation.

I had an insulation contractor check it out. His suggestion was to extend that barrier to the top of the brick by overlapping (and taping) more poly so that the barrier is floor to ceiling. He said he'd put in R-19 unfaced batts if there was enough room...assuming it'd be framed an inch or so from the foundation like you said you do. He also said something about foil faced between the ceiling joists, but I can't remember his exact comment.
For sure if the top is open I would extend it to the top of the wall and seal it there.
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Old 04-24-2018, 06:49 AM   #14
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Re: Basement Insulation - I Dare Ask?


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Originally Posted by Nealtw View Post
For sure if the top is open I would extend it to the top of the wall and seal it there.
Thanks for all the advice. Let me run my final thoughts past you. I'll extend my current vapor barrier to my top plate so it covers the rest of the bricks (keep out outside moisture and off the insulation). I'll frame about an inch away from the foundation. I'll use batt insulation. I need R-13 for code (Thanks Bud). Should that be faced or unfaced? When you said not to use face, that through me off. Is that just a preference based on performance or would that give me trouble? I have a lot of left over faced insulation, so I was planning on using that. That's why I ask.
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Old 04-24-2018, 07:03 AM   #15
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Re: Basement Insulation - I Dare Ask?


The rule is, if you are installing a vapor barrier absolutely only one. Preferably it would be on the inside but you are past that.

Since you are going with a gap behind the wall something needs to hold the insulation in place so use your faced material and cut many diamond (or other) holes to defeat its vapor barrier qualities. The facing makes it easy to install.

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