# Unfinished walkout basement insulation ideas



## y0bailey (Sep 23, 2019)

Hey all! I'm located in Raleigh NC, and I'm looking to add a bit of insulation to my unfinished (and planning on keeping it unfinished) basement. Approx 1400 sq feet. 

It's a walk-out, so really focusing on the framed in sections, unless you tell me just insulating there will be worthless. 

This is new construction and things are pretty tight down there. The main house is spray foam insulated, and the basement ceiling is spray foam insulated.

I have an in-wall HRV down there to move some fresh air in-out (radon issue), and I run a dehumidifer to maintain humidity at 60%, but it gets warm in the summers and cold in the winters down there. 

Humidity control would be an added bonus but seems like a bigger project, and a single 50p dehumidifier does the trick. 










There is the general idea...you can see the concrete foundation and the wood framing. Concrete = below grade, wood = above. 



So, thinking about just slapping some Roxul in there and calling it a day. Just always confused if I need to install a vapor barrier or not?


Thanks for your time!


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## Nealtw (Jun 22, 2017)

I you do insulation only a good chance that some air may get thur behind it providing a chance of condensation and mold.There is nothing wrong with doing the wood structure and the foundation as two separate jobs. Finishing the concrete often is done with a wall in front of it, that would want to be done all at the same time.


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## y0bailey (Sep 23, 2019)

Nealtw said:


> I you do insulation only a good chance that some air may get thur behind it providing a chance of condensation and mold.There is nothing wrong with doing the wood structure and the foundation as two separate jobs. Finishing the concrete often is done with a wall in front of it, that would want to be done all at the same time.


Sorry I'm having a bit of trouble understanding your advice. 

YOU WOULD DO insulation only (and no vapor barrier)

OR

IF YOU DO insulation only you have a chance of condensation and mold.



It's my understanding that vapor barrier WITHOUT drywall is often a no-no, so I'm thinking you are saying to use Roxul only, no barrier, and call it a day?


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## Nealtw (Jun 22, 2017)

y0bailey said:


> Sorry I'm having a bit of trouble understanding your advice.
> 
> YOU WOULD DO insulation only (and no vapor barrier)
> 
> ...


No I would seal the vapour barrier over the insulation. Insulation has to fit snug no holes .


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## Nealtw (Jun 22, 2017)

y0bailey said:


> Sorry I'm having a bit of trouble understanding your advice.
> 
> YOU WOULD DO insulation only (and no vapor barrier)
> 
> ...


 Years ago an unfinished basement looked like this.


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## carpdad (Oct 11, 2010)

Nealtw is in canada, where, I assume, the temps are more extreme than carolinas where you are. Vapor barrier may be needed where temps are as such, but not where you are. I'm in nj and vapor barriers are not a must.
Earth has some insulation effects but that also depends on how deep and how long the freezing temps. I don't think earth will do anything for you looking at the height of the foundation. You have more exposure.

You can insulate but the returns may not be much. Insulating also does not mean cool and warm. It means longer cool and warms, also consistently, if you are cooling and heating. If you want temperate temps while you're in the workshop or such, insulation is a factor but you also have to condition the area with cooling/heating. Dehumidifying helps with feeling cooler.
Also, as a new house, is there a foundation insulation? 
Rockwool has many good points but not with condensation. If condensation gathers on the insulation surface, insulation is not going to be damaged. It's paper and wood that will be damaged. So if you insulate, I think fiberglass will be just as good with paper face facing inside and then drywalling the wall.
Although current insulation calls for at least r13, you could also use 2" or so xps foam boards. Cut them about 1/4" less than the stud bay dimensions and fill the gap with canned foam. With xps, you have lot less chance of condensation and, if you don't need a finished wall, no need for a drywall. Or drywall can be quick joint papered (mostly for air seal) and left unpainted.


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## Colbyt (Jan 27, 2014)

I would definitely insulate framed portions with VB and anything not deeper than 5' below grade would also benefit from insulation, probably closed cell foam. If going over the framed part with foam to create a unified look don't use VB behind it.


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## Nealtw (Jun 22, 2017)

carpdad said:


> Nealtw is in canada, where, I assume, the temps are more extreme than carolinas where you are. Vapor barrier may be needed where temps are as such, but not where you are. I'm in nj and vapor barriers are not a must.
> Earth has some insulation effects but that also depends on how deep and how long the freezing temps. I don't think earth will do anything for you looking at the height of the foundation. You have more exposure.
> 
> You can insulate but the returns may not be much. Insulating also does not mean cool and warm. It means longer cool and warms, also consistently, if you are cooling and heating. If you want temperate temps while you're in the workshop or such, insulation is a factor but you also have to condition the area with cooling/heating. Dehumidifying helps with feeling cooler.
> ...


 I suppose frost depth would be as good as anything for comparison. Ours is 18" 

He is not interested in drywall and if there is any chance of real cold some barrier is a good Ideal. If there is hole in the insulation where air can get thru you can have condensation on the exterior wall. With the barrier cold air could get to the back of the barrier and the condensation will be where you can see it.


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## y0bailey (Sep 23, 2019)

Yea I'm not interested in drywall at this point. 

I do have a window AC unit I put down there during the hottest days (it will hit 80 or so down there mid-summer). Space-heater pointing directly at me in winter...gets into the mid-50's down there in winter. 

But 95% of the time no heating/air used at all....my hot water heater is a heat pump that cools/dehumidifies, but obviously not enough to make a dent in this size of a basement.

Things down there are TIGHT. Caulk, spray foam any gaps, spray foam to the upstairs, tyvek wrap outside and waterproofing on the concrete exterior. Things are so tight that just using my wall mount HRV to move the lowest setting of air makes a significant impact in radon levels (<100cfm setting halves my radon from 4-5/day to 2/day). 

The afternoon, miserably hot sun on my dark blue house and no insulation in the basement is the main thing I'm combating. And a bit of warmth in winter won't hurt.

SO!!!!!! I feel like we have a few different ideas, I feel like I agree that this isn't going to make a HUGE impact long term, and I'm almost more confused than I started. 

Does any of that new info help or alter recommendations? I'm about to just plop some fiberglass in it and call it a day, as I don't think I'm going to have moisture issues in this mild of a climate and that will cost me the least when we are debating if this will have much impact.


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## Nealtw (Jun 22, 2017)

The house should be insulated and it will help when you heat and cool, maybe not enough but some. It is not something that would need to be ripped out to finish the basement.


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## y0bailey (Sep 23, 2019)

carpdad said:


> Nealtw is in canada, where, I assume, the temps are more extreme than carolinas where you are. Vapor barrier may be needed where temps are as such, but not where you are. I'm in nj and vapor barriers are not a must.
> Earth has some insulation effects but that also depends on how deep and how long the freezing temps. I don't think earth will do anything for you looking at the height of the foundation. You have more exposure.
> 
> You can insulate but the returns may not be much. Insulating also does not mean cool and warm. It means longer cool and warms, also consistently, if you are cooling and heating. If you want temperate temps while you're in the workshop or such, insulation is a factor but you also have to condition the area with cooling/heating. Dehumidifying helps with feeling cooler.
> ...


Yea...I'm in the "no vapor barrier" area from the updated recommendations as far as my research has come thus far. We don't get significant freezing or snow. A week or two below freezing at night is typically the max, and usually mid day gets above freezing.


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## y0bailey (Sep 23, 2019)

Alright, here is what I settled on....am I going to ruin my house? I know this is technically against code due to fire reasons, but my reading says that is overplayed and I'm not planning on selling the house or having an inspection.

I bought faced fiber, but stapled with plenty of room for air infiltration and definitely not an air-tight seal. Mostly just to be lazy and hopefully the facing can keep the dust down? Foolish?


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## Colbyt (Jan 27, 2014)

Well, if it makes you feel better.  That is exactly what I would have done. My builder did that exact same thing on the knee walls, all level, in my house. 



I'm still thinking about the closed cell since I have a good bit of concrete wall above the frost line and it is too cool to be pleasant down there in the dead of winter.


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## y0bailey (Sep 23, 2019)

Colbyt said:


> Well, if it makes you feel better.  That is exactly what I would have done. My builder did that exact same thing on the knee walls, all level, in my house.
> 
> 
> 
> I'm still thinking about the closed cell since I have a good bit of concrete wall above the frost line and it is too cool to be pleasant down there in the dead of winter.


You did make me feel better! So thanks!


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## Barthugens (10 mo ago)

y0bailey said:


> Hey all! I'm located in Raleigh NC, and I'm looking to add a bit of insulation to my unfinished (and planning on keeping it unfinished) basement. Approx 1400 sq feet.
> 
> It's a walk-out, so really focusing on the framed in sections, unless you tell me just insulating there will be worthless.
> 
> ...


Walls should always be blanket coat insulated from the outside, under the siding, and with a rain screen air gap between insulation and siding. Never insulate the inside walls of a basement as you'll always have moisture, mold, dampness issues. Insulate the outside and the inside walls will always be dry and warm.


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## Nealtw (Jun 22, 2017)

Barthugens said:


> Walls should always be blanket coat insulated from the outside, under the siding, and with a rain screen air gap between insulation and siding. Never insulate the inside walls of a basement as you'll always have moisture, mold, dampness issues. Insulate the outside and the inside walls will always be dry and warm.


Hmm, interesting concept, not very practical.


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