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Tony Wang
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Basement damp and water intrusion

Tony Wang
Posted Jun 14 2022, 00:28

I have a property in Seattle with a basement apartment. It is below grade and built from a crawlspace (still have half of the crawlspace remaining). The previous owner likely did not do it properly because it is a nonconforming basement.

The emergent issue is that the basement is pretty damp. The humidity level is always 70 to 80. Running a dehumidifier helps but then I cannot open the windows. It has the basement smell or the damp smell, which may likely cause mold issues but I haven't seen anything obvious yet. I don't see water intrusions no matter how heavy it rains. However, when it snows heavily which is once or twice a year here, I could see the water coming in from the cove joint.

I talked to two foundation companies. Both of them suggested burying a sump pump in the basement to deal with the water intrusion, and the damp issue will go away after that. However, it doesn't seem to be a good idea to do anything inside the basement according to the posts I see here, and I don't know how that can magically resolve the damp issue. Any suggestions on what to be done, and where I can learn more about this?

Also, who should I talk to, a foundation expert, a basement expert, or a GC? Any local recommendations are appreciated!

PS: I am also looking to get it up to code and maybe add an egress window on the other side as it has no natural light coming in. Is this something that can be included in the same effort?

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Greg Scott
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Greg Scott
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Replied Jun 14 2022, 05:38

Grading, grading, grading.  As an expert on these issues once said to me, keeping water away from the foundation solves 90% of water intrusion problems.

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Marcus Auerbach
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Marcus Auerbach
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Replied Jun 14 2022, 06:30

We deal with this a lot in Milwaukee, even tough our basements are built differently, the principles are the same.

First line of defense is surface water management: gutters, down spout extensions and grading. The soil around your house should always be dry when you take out a scoop with a shovel. If your soil is wet, your basement will be too.

A sump crock is the next step, as it helps get water out from under the house. In Wisconsin houses have an inner and an outer drain tile system, basically a pipe with holes that runs around the foundation and collects all the water and then guides it into the sump crock, from where you can pump it out and discharge far away from the house.

A dehumidifier is your last line of defense, but if #1 and #2 are done correctly and you have proper ventilation (install a super quiet high CFM fan on a humidity switch) you should get down to pretty low levels.

You want to talk to a basement contractor, they specialize in foundation and water issues and have the crews to deal with it.

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Sherief Elbassuoni
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Sherief Elbassuoni
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Replied Jun 14 2022, 07:22
Quote from @Tony Wang:

I have a property in Seattle with a basement apartment. It is below grade and built from a crawlspace (still have half of the crawlspace remaining). The previous owner likely did not do it properly because it is a nonconforming basement.

The emergent issue is that the basement is pretty damp. The humidity level is always 70 to 80. Running a dehumidifier helps but then I cannot open the windows. It has the basement smell or the damp smell, which may likely cause mold issues but I haven't seen anything obvious yet. I don't see water intrusions no matter how heavy it rains. However, when it snows heavily which is once or twice a year here, I could see the water coming in from the cove joint.

I talked to two foundation companies. Both of them suggested burying a sump pump in the basement to deal with the water intrusion, and the damp issue will go away after that. However, it doesn't seem to be a good idea to do anything inside the basement according to the posts I see here, and I don't know how that can magically resolve the damp issue. Any suggestions on what to be done, and where I can learn more about this?

Also, who should I talk to, a foundation expert, a basement expert, or a GC? Any local recommendations are appreciated!

PS: I am also looking to get it up to code and maybe add an egress window on the other side as it has no natural light coming in. Is this something that can be included in the same effort?

 @Tony Wang, Make sure your gutters and downspouts are functional. You will also need a french drain outside of the home to drain water away from home. French drain is basically a dig filled with rock so that water flows through it. Finally, you will need a sump pump. If the basement is already finished, you may need to re-do the flooring of the home

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Rebecca Knox
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Rebecca Knox
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Replied Jun 15 2022, 07:00

You might also want to start off talking to an engineer who does not do foundation/basement repairs and therefore, has no vested interest in upselling you. 

We have exceptional basement repair people in Milwaukee but I always hire an independent engineer to give me a report (typically $400-$500) and then have the foundation guys quote off of that. 

Marcus is a gold mine of knowledge and I agree with everything the says. Here in Milwaukee and surrounding areas, we are very familiar with foundation/basement issues.