How much does it cost to finish a basement so that it won't flood?

Asked by Milnere, Portland, OR Sun May 15, 2011

Our basements gets water any time it rains heavily. How much does it cost to seal it off and then finish it?

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Marvin Von Renchler’s answer
Marvin Von R…, Agent, Tigard, OR
Sun May 15, 2011
Ditto Dans answer. You may need drains, having the exterior of the walls sealed, they could be cracked or crumbling---cement only lasts so long and its a different mix now. Call the local contractors board and ask for a specialist. You didnt say how old it is or what type of basement, how much water, etc etc.

Regarding finishing---oh buy, that depends on your pocket book.
1 vote
Janeese Jack…, Agent, Portland, OR
Sun May 15, 2011
M: Dan is correct, there's no way to answer that question without a lot more information. I see a lot of property inspections where leaking and overflowing downspouts and gutters are major contributors to water in basements. But, you may need a more elaborate solution! I would call a good drainage company such as:
M. Leon Construction at (503) 643-6631 or Ability Plus Drainage at (503) 246-0474. They will give you an assessment and bid on the work.
Good luck!!!
Janeese Jackson, Principal Broker
Real Estate Resource
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1 vote
The Stephen…, Agent, Portland, OR
Wed Sep 12, 2012
It depends on the basement. I've helped two home owners seal their basements in the last year and one ran 10,000 and the other ran 4,000, so it just depends on your situation.
0 votes
Carl Heldmann, Other Pro, Charlotte, NC
Tue Aug 21, 2012
Dear Milnere, it is impossible to have a dry basement without eliminating the source of water outside your house. There is no method or product to my knowledge that will keep water out of your basement.

Think of the Grand Canyon and you will realize that water will go where it wants to and it always flows downhill.

All basement water problems and basement moisture problems are caused by poor or improper drainage of rain and runoff water outside the house.

When trying to fix water problems on an existing home, or prevent them on new construction, there are no shortcuts.

Get rid of the water and you get rid of your problem. You can read how to on my Wet Basements article (

Good luck,
Carl Heldmann
0 votes
Dave Sutton, Agent, Portland, OR
Mon May 16, 2011
Marvin asked a good question about what you mean by
0 votes
Joan Bowyer, Agent, Gresham,, OR
Mon May 16, 2011
Milnere: Tom Ingelsby covered all of the things that would cause water into the basement. With my 29 years experience these have all shown up. I have a friend in New Jersey who had the same problem and he had multiple issues causing water into their basement and like Tom I had suggested they check the same issues. This is more common than one would think. Good luck with that and make sure you do check contractors licenses with the contractors board. Joan Bowyer-Principal Broker-John L. Scott-503-260-2416.
0 votes
Lana Lavenba…, Agent, Grants Pass, OR
Mon May 16, 2011
It depends on what you have to do to get to the basement. Do you need to dig out around the full basement put the sealer on and then the paper to keep it from seeping back again? Or just on the inside sealing it? Sounds like to me the digging around the basement to put sealer on the outside and then the paper is what you need to do. I dont know what it will cost because I dont know where you live!
0 votes
Tom Inglesby, Agent, Portland, OR
Sun May 15, 2011
Milnere. It depends on many things, Where are your cracks in the wall or the base where the wall meets the floor? There are expanding products that go in the cracks and others that go at the base. But first of all the water is coming from the out side. Some time the drainage on the exterior needs to be changed so the water runs away from the house I think the new code for slope is 6 inches high at house running 10 feet out away from the house to get the grade to flow right for rain water. The south and west sides are the most important. Do you have window wells that can collect water is another area of concern? Gutters and downspouts are the problem most of the time. If you walls were not oringinally poured with a good mix of concrete and you can see many rocks in the walls you might just need a skim coat of a good epoxy cement? If you have an old house the foundation drain that goes around the base of the foundation that collects the downspout rain water this will clog with roof granules and dirt. Disconnect the gutters and run the water from the back and sides to the front of the house in plastic pipes and discharge the water at least 5-10 feet sloping away from the house and see if this stops or solves the problem? In the City of Portland you are not allowed to dump water on you neighbors property with in 5 feet of the property line. Check to see what your neighbors are doing with their roof water? With the City of Portland disconnecting downspouts more basements are flooding in neighborhoods. Some areas like Westmoreland have a high water table and leads to more problems since the water is not that far down and any cracks are just spots for water to come in the basement. The solution for water coming up thru the floor is cut a 1 foot section at the base of the wall in the floor around the basement and put pipe and rock and run it to an area for a sum pump to pump the water out of the collection plastic bucket. Ames water proofing has a product that goes on the wall with brush or roller and will seal it and it is very good but it will not stop or fill large cracks. it is $150 for five gallons but great stuff. If you are getting a fuzzy walls that when touched are powdery, you are getting moisture leaking thru the wall you are not getting any water just slight water penetration from the exterior and that product will stop that. Most contractors want to do an over kill to guarantee no problems but if you try the gutters draining first that will probably stop most of it and then other options are more reasonable because you do not want to finish off the basement walls and have the problem again. Jay Buce concrete could help you 503-631-8700. I had an estimate for 50 feet of drain pipe and floor cut out and sump for $5000 very easy to do at 1/3 the price if you did it your self. Good luck
Tom Inglesby, Broker
RE/MAX Equity Group
0 votes
Marge Bare, Agent, Clackamas, OR
Sun May 15, 2011
Hi Milnere,
As everyone here has said, it's impossible to say without getting some solutions from experienced foundation and water issue companies. For a flooding basement I would definitely find someone to do it right! Anyone you hire should be a Licensed Contractor and I would recommend that you check their license background at the Oregon Contractors Board website: see link below.

I'm not saying these are the right contractors for you or your job, you'll need to interview and decide who has the best solution for you. But myself and/or my clients have had good experiences with John's Basement and Pascal at M Leon Construction. They're both local and it would be easy to find their contact info. Of course, our experience isn't necessarily everyone's experience so you'll want to do your own diligence in selecting someone.
Best of luck! send me an email if you have any questions
0 votes
Dan Tabit, Agent, Issaquah, WA
Sun May 15, 2011
No way to answer that question. Some issues may get resolved with improving the drainage from outside and can cost very little. Others may require major excavation to expose the concrete and seal it.
I would start by checking the downspout. Are they dumping the rain right next to the house or are they tied in to a drain line leading away from the house? Are their tree roots penetrating the foundation creating access points for water?
If you are seriously considering buying a home with these issues start with a good inspector and consider what they have to suggest. If necessary you may need to talk to contractor who does this type of work. Your inspector or agent may have a referral for you to consider. Best of luck.
0 votes
Mary Jean Ha…, , Portland, OR
Sun May 15, 2011
I am not a contractor, and I can find you someone who can answer that question. Just email me at and I can make multiple referrals to the experts in our area! Likely it will take a detailed explanation of your basement situation and more often, a visit by the contractor to give you a good bid.
Mary Jean
0 votes
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