# Should I put new insulation in the basement?



## word2yamutha (Mar 13, 2013)

They did a poor job insulated the basement from what I can tell. Some of the insulation has mold on it and I think they might be a reason for some bug issues in the basement. I'm not sure if this type of insulation is suppose to be stapled in or what not, but it can be easily pulled out by hand.

I was going to buy some of this http://www.homedepot.com/p/Owens-Co...Insulation-RF10/202585857?N=bay7#.UXGbWcoeK8c

I went ahead and measured it out and I need about 5 rolls of this. I thought about cleaning behind the old insulation if this is ok? What is the proper way to install insulation?


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## joecaption (Nov 30, 2011)

It's moldy because no one foam sealed the gaps and used styrofoam to finish sealing up that area.


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## word2yamutha (Mar 13, 2013)

Do you recommend a certain product?


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## joecaption (Nov 30, 2011)

Great Stuff and 2" thick blue foam you can get at any box store.


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## word2yamutha (Mar 13, 2013)

So put up the 2" foam board first then the batting?


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## joecaption (Nov 30, 2011)

There has to be hundreds of post on this exact subject under insulation.
Just go to the search funtion.


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## word2yamutha (Mar 13, 2013)

I mostly get insulation for basement walls results. I just didn't know how to properly insulate because we are leaving the basement unfinished.


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## Gary in WA (Mar 11, 2009)

You can DIY SPF or use rigid foamboard/canned foam, as Joe said. http://www.buildingscience.com/docu...joist/files/bscinfo_408_critical_seal_rev.pdf
Also, caulk the mudsill/concrete gap against air ifliltration/exfiltration as this may be the source of the moisture in the air condensing on the wood. If there is a poly sill sealer under the p.t. plate, you have a water problem elsewhere as the bottom of the I-joists should not be wet. Another picture of the outside wall at siding level about 6' away would help. It may be the siding drip edge doesn't go below the mudsill and more flashing is required.

Gary


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## gregzoll (Dec 25, 2006)

joecaption said:


> It's moldy because no one foam sealed the gaps and used styrofoam to finish sealing up that area.


If it was mold or mildew, it was due to because water or moisture got between the insulation and the OSB, due to temperature differences between the cold side and the warm side of the insulation.

I have Batts around my basement Sill & Joist bays, and do not have a issue with mold or mildew. Only place that I have ever gotten it, was under the tub, due to water got between the tub surround that we installed, and the tub, due to a gap, from the tub being not even along the wall, to begin with, from when they put it in back when the house was built in 1937.


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## Gary in WA (Mar 11, 2009)

Your bottom of the sub-floor looks similar to this current one; http://www.diychatroom.com/f17/bathroom-exhaust-duct-177230/

No sill-sealer = moisture; http://www.greenbuildingadvisor.com...ressure-treated-sill-plates-and-building-code

I agree with Joe, stop the air leaks, use f.b. not f.g. at the rims; http://www.diychatroom.com/f103/fiberglass-okay-walls-but-not-rim-joist-170864/index2/

Gary


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## word2yamutha (Mar 13, 2013)

Does it matter what kind of caulk I use for the mudsill? I went ahead and uploaded the other picture because it looks like this is only a problem from the front of the house(the concrete wall pictured is the front of the house). The other concrete walls don't look like this.

Didn't know the foam board was going to be so expensive. I was checking out this one http://www.homedepot.com/p/Owens-Co...d-Edge-Foam-45W/100320352?N=baxx#.UXLmn8ow-8c


so after I caulk I should put this up? http://www.homedepot.com/p/Owens-Co...FS/202080947?keyword=sill+sealer#.UXLnjcow-8c

Would it be cheaper to use can foam? If so, is there a brand you guys recommend? Thanks for the help so far guys, much appreciated.


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## Gary in WA (Mar 11, 2009)

At better picture, you don't need the sill-sealer, it is already in place. All the moisture streaks on concrete are a clue...

The rim joist area is similar to a wall; distance/depth of cavity insulation from the heat source to the foamboard; http://www.buildingscience.com/docu...ulating-sheathing-vapor-retarder-requirements Notice, the more cavity insulation= the thicker f.b. required to prevent condensation on the inside the f.b. There will be no condensation on the rim as it is air/moisture sealed from basement air. I'd go with the higher thickness listed for 2x6 wall, to compensate finished drywall in the basement later. I could figure the dew-point, if I had your largest closest city name... below the map; if in Zone 4, or Zone 5; http://publicecodes.cyberregs.com/icod/irc/2009/icod_irc_2009_11_par002.htm

Gary
PS. Is there brick veneer on the other side of rim?


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## word2yamutha (Mar 13, 2013)

no brick veneer on the outside. I live in zone 4 about 40min away from columbia, MO. So the wet looking part on the concrete is the sill seal correct? So go ahead and caulk where the wood meets the concrete?

So when installing the foam board it doesn't touch the concrete part, correct?


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## gregzoll (Dec 25, 2006)

If all they used was that foam stripping between the framing and the concrete, that right there is why you are getting moisture pulling into the house from the outside. You have to love how homes are built these days, compared to back in the day, when they were built to last.

You are lucky if homes built these days to last more than 10 years, before they start falling apart.


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## Gary in WA (Mar 11, 2009)

Sill sealers are designed to stop air/moisture/low water absorption/insects. It is the best you can have, and you have it; https://docs.google.com/viewer?a=v&...QOWz4S&sig=AHIEtbTcOmZPzl_CNTmOSf-fmaa9ayOUVg

I am concerned you have a water source at the mudsill, wetting the joist bottoms as pictured. They should be dry. Your exterior flashing/housewrap is defective there. What type of siding---- a picture of outside house would help- 8' away...

you may be able to remove a bottom course and add sill flashing there; http://www.ebuild.com/articles/470010.hwx

Gary


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## RWolff (Jan 27, 2013)

word2yamutha said:


> I mostly get insulation for basement walls results. I just didn't know how to properly insulate because we are leaving the basement unfinished.


It's been said that leaving insulation exposed is a bad idea, I think the insulation itself even says not to leave it exposed, though it's usually due to the kraft paper/foil they put on.
I believe too that this insulation will actually burn if it gets hot enough, the rigid styrofoam board, Celotex, styrene etc definitely WILL burn and must be covered.
A house around the corner from me undergoing some long term renovations while the fmaily lived in it had exposed insulation the fire marshall said, one night a hanging ceiling lamp cord caught in a metal hide-a-bed's frame earlier finally gave out and shorted, it started a fire in there around 2 AM, the fire dept said that by the time they got there the entire house was in flames which were coming out the windows. They said the exposed insulation in the ceiling etc had gone up so fast there was no chance anyone could have been rescued or made it out alive.
A woman and 3 kids burned to death in that fire, there were no smoke detectors, or fire extinguishers.
They did not specify exactly what kind of insulation the house had, but the debris pile did have some puffs of the yellow fiberglass insulation in it I noticed.


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## Gary in WA (Mar 11, 2009)

Never leave paper-faced insulation uncovered in a basement, as you said. SPF is allowed left uncovered under certain requirements; http://publicecodes.cyberregs.com/icod/irc/2009/icod_irc_2009_3_sec016_par015.htm

Glad you reminded me to mention-- use Thermax --- http://building.dow.com/na/en/products/insulation/thermaxsheathing.htm---- or R-max (foil-faced) and acceptable for most/all building departments without the thermal fire barrier, and--- check with local AHJ.http://www.rmax.com/specialty-products.asp

Thanks again, RWolff! Glad you're awake...

Gary


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## word2yamutha (Mar 13, 2013)

So the moisture coming in is from the house not being properly insulated from the outside? Would it be ok to go ahead and replace the current insulation with the rigid foam board?

There is also a product called roxul. Would this be better then the foam board?


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## gregzoll (Dec 25, 2006)

word2yamutha said:


> So the moisture coming in is from the house not being properly insulated from the outside? Would it be ok to go ahead and replace the current insulation with the rigid foam board?


 Actually the moisture is from both inside & outside. What needs to be done first, is seal any air gaps, before you do anything.


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## word2yamutha (Mar 13, 2013)

do I need to seal with caulk where the sill sealer is?


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## gregzoll (Dec 25, 2006)

word2yamutha said:


> do I need to seal with caulk where the sill sealer is?


Yes you need to seal along the rim & sill joist areas, along with any areas, that pipes & wiring enter the attic space, before you can do any insulation.


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## word2yamutha (Mar 13, 2013)

Does it matter what type if caulk I use?


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## gregzoll (Dec 25, 2006)

word2yamutha said:


> Does it matter what type if caulk I use?


Window & door 35 year usually works, or the gray silicone based caulk, so it will flex with the house.


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## Gary in WA (Mar 11, 2009)

Cold you give us a picture of the siding on that rim joist with the water wetting (first photo), from the exterior?

Gary


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