Categories: BasementsDesign

Refinishing A Flood Damaged Basement

Another homeowner has emailed me with questions about insulating a finished basement. This situation is a bit different and I wanted to share it with you. The homeowner recently had their basement flooded with over 4 feet of standing water. The house is located in a flood plain but has never been flooded before. The flood was part of a very unusual flooding event that FEMA declared a disaster. The damage was extensive including cracking and buckling of the existing concrete block foundation walls. The foundation walls have since been repaired and steel reinforcing columns have been installed to shore up the house. The homeowner wanted to know my thoughts on how he should insulate the basement before they create their new “Man Cave”. Below are some of my thoughts about this particular situation.

Insulating A Flood Damaged Basement
The following items were my thoughts / suggestions to this homeowner regarding his situation.

I always advise customers that it’s not a great idea to put lots of money into a basement in a flood plain. Even though this flood hasn’t happened before there’s certainly no guarantee that it won’t happen again next year. Having said that be sure to consider the issue and be prepared for that possibility.

At the very least I’d recommend they have a sump pump system installed in the event of future flooding again to help remove the water and hopefully keep the levels from rising above the finished floor level. However, this approach may not work if in fact the yard is flooded and there’s no place to pump the water to.

Considering the basement has previously flooded and there is a possibility of it in the future I’d recommend they only insulate the basement with some type of foam insulation. This will help prevent any mold issues in the future should the basement become flooded again. I’d also recommend that they frame the walls with pressure treated lumber again to prevent future damage due to water damage.

The difficult decision will be what material to use on the walls. I would certainly stay away from drywall in this basement. It will only take one flooding event to render it useless and a potential mold hazard. I’d recommend they look into some type of non-wood, non-paper paneling product (not really sure what to recommend). At the very least using some type of water/rot resistant wood might be the best approach if you can’t find a suitable product.

Finishing Basements In Flood Plains
Deciding to insulate and finish a basement in a flood plain is a risky investment. Even though you may have a dry basement with a history of never flooding it’s quite possible that a flood will over take your house and basement. Flood plains are identified by the U.S. Army Corps of Engineers. These zones have been identified based on historical and analytical data and represent a very likely set of locations for flooding.

So I caution folks to be very wary of spending money and investing in finishing a basement when you live in a flood plain. You are running the risk of severe damage and most likely no insurance coverage on your investment. If you must finish your basement then you should design it in such a way as to minimize the effects of flood waters.

Todd Fratzel

I'm full time builder for a large construction company in New Hampshire. I run their design-build division that specializes in custom homes, commercial design-build projects and sub-divisions. I'm also a licensed civil and structural engineer with extensive experience in civil and structural design and home construction. My hope is that I can share my experience in the home construction, home improvement and home renovation profession with other builders and home owners. I'm also the Editor-in-Chief and Founder of Tool Box Buzz. Please feel free to contact me if you have any questions, suggestions or you'd like to inquire about advertising on this site.

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View Comments

c says:
January 8, 2009 at 6:57 pm
Timely article since our state (WA) is currently having flooding issues. Even though we have never had severe flooding around our house, we have seen a tiny bit of water steep in from where wall and floor meet... I'm curious what material you would recommend for flooring?
We are finishing our basement partially. It's all concrete floor at this moment.
No wood, no laminate, right? I'm thinking about tiling, but is it really flood safe?? Any tips for installing tiles in basement to prepare for possible water?
Not safe to use electrical floor heat even it's varied in concrete??
This may lead another article, it would be great, too. :)
Thanks!
Todd - Home Construction Improvement says:
January 8, 2009 at 7:05 pm
@ C - I prefer ceramic tile on concrete floors in the basement. The key is to use a thin set mortar and NOT A MASTIC. Thin set mortar are a cementitious material similar to concrete. It's also important to chose a grout that's made for wet applications. There are a few grouts on the market that are similar to mastics and I would stay clear of those.
As far as electric radiant it's certainly an interesting question and one best left to an electrician. My guess is it would be fine when it's burried in the thin set. These systems obviously are designed to deal with shorts.
Anonymous says:
January 9, 2009 at 7:35 am
We used the Dricore subfloor system in our basement with great success. We wanted carpeting in our home theater to deal with sound issues and Dricore deals with both moisture issues and cold transfer from concrete. We don't have water issues and are not in a flood zone, so carpeting should serve us well. I think we paid about $1.50 - $1.60 a sqft. Money well spent, especially evident in the cold of winter and the basement is warm and cozy. Just another option for people to consider.
c says:
January 9, 2009 at 12:49 pm
Thanks for your tips! I didn't know there is different kind of grout made for wet application. Thank you!
Dricore looks great, it would keep warm the basement for sure! I'm going to check how thick these are (our basement ceiling is not too high!), and double check with their customer support to see how much of "moisture" they can take in case of small amount flood water came in.
Thanks both!
Karen S says:
January 13, 2009 at 10:50 am
Thanks for the information about the Dricore - it looks like just the stuff I have been thinking about using.
andrew says:
January 15, 2009 at 9:39 am
If your basement floods somewhat why not set your sheet rock above the high water mark and use another material (fake beadboard) within the potential water level that is removable if you take off trim.
I ran across this in a relatives place, for new insulation they used the poly spray foam which I don't think will retain the moisture once it dries. They cut the damaged sheetrock 6" above the water level and use a fake wood plastic material painted for the base.
Todd - Home Construction Improvement says:
January 15, 2009 at 9:46 am
@ andrew - That is certainly an option worth considering. It's a much better idea compared to putting back water sensitive materials.
george hammond says:
February 12, 2009 at 8:41 pm
Hello, first time visitor to your site. Excellent information, Todd. I live in Pennsylvania and have a flood damaged basement (2 feet of storm water, 2 different hurricanes, 2 weeks back to back). I removed my drywall and sopping wet fiberglass insulation and have been pondering for four cold years on how to re-do the insulation. I'm worrried about another flood as I have small stream in my backyard. I am considering tearing down the 2x4 stud walls to insulate with 1" blue board. I just learned about the Tyvek tape from your site -thank you! I appreciate the tip from Andrew on Jan. 15th regarding the beadboard/sheetrock approach. Thinking of the same approach but I'm conscerned about the poly spray foam as I think it will indeed soak up and retain moisture. I'm thinking of using extruded foam board in the stud cavities. Cost effective? Probably not. Expensive? Sure. Warm and dry? I hope so. Any thoughts?
- Todd says:
  February 13, 2009 at 4:24 am
  @ George - Thanks for the compliments. You need to make sure what ever type of foam you use is "closed-cell" which means it will not absorb water. I'd also recommend you look into a good sump pump system to try and reduce the amount of standing water you get in a flood situation. Best of luck.
Daren says:
February 25, 2011 at 2:05 pm
I have had floods twice in 30 years. I soled the problem by using extior stucco [made by same company that makes Durarock. for the walls. Looks great but a little pricey [$25.00 for 4x8 sheet]. I used poraclien tile on top of Ditra for the floor membrane.
Daren says:
February 25, 2011 at 9:19 pm
I sorry, I was mistaken. It was Hardipanel from James Hardie.