Do I Need To Waterproof My Basement Prior To Having It Finished? - Building & Construction - DIY Chatroom Home Improvement Forum

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Old 01-06-2017, 02:49 PM   #1
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Do I need to waterproof my basement prior to having it finished?

Our home is 30 years old, poured concrete foundation with no visible cracks. The sump pump rarely comes on and we’ve never had standing water. However it will have that damp basement feeling from time to time.

We're having a contractor finish over 900 square feet of livable space and we really don't want it to feel like a basement.

I’ve had waterproofing companies out to provide their “suggestions” and they all entail at least $5000 of waterproofing work- things like digging out the floor at the foundation to install drainage systems.

Is this really necessary to avoid a damp basement? Would like to get the thought of others that have faced similar situations. I don't want to put all the time, effort any money to put up new walls only to tear them down due to mold.
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Old 01-06-2017, 03:44 PM   #2
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Re: Do I need to waterproof my basement prior to having it finished?

The answer is you probably do. That said, anything on the inside is not waterproofing, it is water mitigation. Waterproofing is done on the outside with gutters, downspout extensions and grading.

Have you ever done a moisture test on your slab?
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Old 01-06-2017, 04:17 PM   #3
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Re: Do I need to waterproof my basement prior to having it finished?

Hi Nick and welcome to the forum.
It sounds like you are familiar with that damp basement smell. Unfortunately it isn't just due to liquid water but moisture vapor as well. Upgrading your basement to quality living space will be a challenge and will certainly require a chunk of that $5,000. But I've seen efforts like that fail as well.

Like ss said, you start on the outside. Then you forget that "waterproof" word, not going to happen within a reasonable budget. There are many threads here on this topic and I'll add a link on basements to get you started.

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Old 01-07-2017, 07:45 AM   #4
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Re: Do I need to waterproof my basement prior to having it finished?

Concrete may be porous or more impervious (I think depending on its strength) but unless vapor blocking was done from outside all around and under the slab, basement must be more humid than other floors. That means no kind of WATER (not vapor) proofing will get rid of the bsmt smell because the mold will grow on enough vapor that turns into enough moisture. Here in NJ that happens only in warmer weather and I ran a dehumidifier 24/7. Better if you can locate it near a drain. I emptied the bucket every 2 days or so.
In another house, just running a small fan all summer in unfinished bsmt solved the smell problem. Must have a make up air from somewhere for the water heater, drier, etc.
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Old 01-07-2017, 08:20 AM   #5
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Re: Do I need to waterproof my basement prior to having it finished?

if theres no signs of water getting in your fine. all your experiencing is high humidity in the air.. this is extremely common in homes that dont have venmar units in them.. all you need is a dehumidfier
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Old 01-08-2017, 11:08 PM   #6
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Re: Do I need to waterproof my basement prior to having it finished?

-----------------Welcome to the forums! --------------------------

I agree with Kirk.
IF you had water showing on the walls, use XPS foamboard or SPF, if not, fibrous insulation per Energy Code is fine. With that old a house, you probably don't have perimeter foam under the slab; use some 1/2" foil faced under the wood plate to stop thermal conduction (warm the wall- warm the earth) and stops capillarity- wetting the studs; that may be evaporating due to air currents now, and it air seals so any room moisture doesn't condense on the colder concrete wall. Links if you need them...

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