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I am starting to finish my basement in my house that was built in 2015. At this point I have not seen any sign of moisture in the basement. It's 8" poured walls. I did see during construction a layer of some kind of green stuff sprayed on the exterior walls and then that was covered with plastic. There was also some sort of black drain pipe going around the foundation. Question is do I still need to waterproof the interior walls before finishing the basement with drylock or some kind of sealer? The house is in Carolinas. Thanks for any help :smile:
 

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Naildriver
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No, the best waterproofing comes from the outside as you have described. There will be inherent moisture created by the differences in temperatures of the ground outside and the warmer air inside, but it will dissipate, normally. Is it a walkout basement, or is it totally enclosed with dirt?

In some climates it is recommended to glue 2" XPS to the wall and seam tape in an effort to keep temperature changes to a minimum. In your climate, it may not be necessary. Build your wall about 1" away from the concrete and insulate it using a vapor barrier on the interior side, or use Roxul (Rockwool) batts which will require no vapor barrier.
 

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2x. In addition, help your excellent drainage system with landscaping that slopes away from the house and does not drain well straight down the foundation. That means not too much mulch. Sorry but I'm inclined to no flower beds around the house.:smile:
 

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Discussion Starter #4
It is a walkout basement and is on top of hill. ground is sloped away keeping water away from foundation. On the wall where built the bathroom i used Owen's corner foamular 150. It's the 1" . I glued it directly to the cement then built walls with no insulation thinking the foamboard acted as vapor barrier and isulation. So do I need to use the 2" or is the 1" ok? Also do I still need use insulation batt insulation with me using the foamboard?
 

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A small point of definition: Waterproofing is done on the outside through means like gutters, downspout extensions and grading. As mentioned, this would be what you would want to do. Anything done on the inside, like Drylok, is water mitigation where you're dealing with the water after it's already inside the structure.

The idea behind the foam on the concrete is to create a thermal barrier to prevent condensation. While it is not a vapor barrier it does slow the transmission of vapor (called a vapor retarder instead) and thus you are allowing your wall to dry to the inside. If it's not thick enough, it does not prevent condensation. Unfortunately, I do not have the charts which explain what thickness is required based on location; hopefully Bud can stop by with that information shortly.
 

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retired framer
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I am starting to finish my basement in my house that was built in 2015. At this point I have not seen any sign of moisture in the basement. It's 8" poured walls. I did see during construction a layer of some kind of green stuff sprayed on the exterior walls and then that was covered with plastic. There was also some sort of black drain pipe going around the foundation. Question is do I still need to waterproof the interior walls before finishing the basement with drylock or some kind of sealer? The house is in Carolinas. Thanks for any help :smile:
no..........
 

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Naildriver
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Here in the South you should be OK with 1" XPS, but be sure to tape any joints you have with something like Tyvek tape. It helps to keep what is behind the XPS back there. You will have better control of HVAC if you go ahead and insulate the joist bays, especially in the walk out areas.
 
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Discussion Starter #8
So if I use Roxul batts I will not need the plastic vapor barrier. I would have the foam board directly on the cement, then frame the wall about 1in away, then install roxul batts and I ready for sheetrock? Thanks
 

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So if I use Roxul batts I will not need the plastic vapor barrier. I would have the foam board directly on the cement, then frame the wall about 1in away, then install roxul batts and I ready for sheetrock? Thanks
Check with your building inspector regarding vapor barrier - local codes vary
 

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Personally, I would not use the plastic vapor barrier regardless of the choice of insulation but you must comply with local codes so check with the AHJ first.
 
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