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Several years ago I started insulating my basement on our 1915 Bungalow. At the time, I know I did a lot of reading up on how to do it correctly, but today, while looking up the difference between the white foam and the blue, I came across some articles online that have me a little concerned.

My house is built on, what I am pretty certain is mostly hollow concrete block foundation. Can't be positive it's all hollow, but the stuff I've messed with has been and that seems typical around here. In any case, I adhered blue foam board to the inside walls, then I spray foamed all of the joints and seems, top and bottom and where the pieces meet. I also attempted to use rigid and spray foam to cap off where the tops of the concrete blocks meet up with the sill plate. For the joist bays, I installed several inches worth of rigid foam and spray foamed any gaps.

Once I had the walls foam boarded and sealed up, I then built a 2x4 wall over that and insulated the bays with fiberglass batting, then installed the sheet rock. I'd say I have about 60% of the basement finished and it has helped it a lot in maintaining a pretty steady 65-70* temp.

Like I said, I am pretty sure I read, re-read and even studied the documents on the material I used, BUT today I'm reading that installing the foam board over the interior walls can trap moisture and thus create mold between the foundation wall and the foam. Is this true? Have I done a bad thing?

I'm in Central Kansas, so our temps are pretty much 50% heat and 50% cool and if I'm correct because of that any vapor barrier can really go on either side of the wall. In fact, I also blew cellulose into most of my exterior walls and when I was reading up on that, I recalled seeing some people complaining that can also cause rotting from the inside out, but on that one I called the Head Inspector for our locality and he said in his 30-40years on the job, he'd never seem an issue where a dwelling in our area had a problem like that.

I'm getting ready to install some more foam board, so I can continue finishing another area, before winter gets here, but I don't want to do something I maybe shouldn't be doing....
 

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Bulk moisture that is coming through the block will come through and you will have to address that from a foundation standpoint with grading and proper gutter routing.

As long as you sealed up everything, condensation (as a result of diffused moisture in the air) during the winter months should not happen on the wall.
 

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Bulk moisture that is coming through the block will come through and you will have to address that from a foundation standpoint with grading and proper gutter routing.

As long as you sealed up everything, condensation (as a result of diffused moisture in the air) during the winter months should not happen on the wall.
The grading has been properly addressed all the way around as I did have some issues with water intrusion after heavy rains due to poor grading. I did find a few bad motor joints below grade that were repaired and I've built up and directed water away where it was an issue.

As for sealing everything up, I was very anal about that and believe there are no gaps. I ran the foam from the slab all the way up, sealing the entire way. I then built my walls and even placed rigid foam on top of the bottom plate, then spray foamed those joints. I didn't want any chance of the fiberglass to get moist and I figured any water/moisture that might collect in the channel that was somewhat created and have some chance to dissipate.
 

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I've heard people say that before and always wondered if the mold is present, but sealed from the living space, is it really a big deal? Obviously not a great thing to have, but if you're not tearing into it, you shouldn't be exposed to anything.
 

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Did you leave a space between the 2x4 framing and the foam insulation? I can't tell from my research if you only do that when you don't use the foam insulation or if you should do it along with the foam. Can anyone else clarify the proper method?
 

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Did you leave a space between the 2x4 framing and the foam insulation? I can't tell from my research if you only do that when you don't use the foam insulation or if you should do it along with the foam. Can anyone else clarify the proper method?
Most times the walls aren't quite square or plumb so there is a small gap depending how you lay out your walls.

You should be filling the 2x4 spaces with batt insulation so if the gap is a consistent 1-2" around, use a 2x6 batt and the extra gap will be absorbed and filled by the additional batt depth.
 
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