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-   -   Do I need to waterproof my basement if I already have a french drain? (http://www.diychatroom.com/f19/do-i-need-waterproof-my-basement-if-i-already-have-french-drain-67155/)

buratti 03-19-2010 08:51 AM

Do I need to waterproof my basement if I already have a french drain?
 
My basement flooded for the first time since we lived here and I was now told that I should waterproof my basement. I am uncertain if waterproofing will do anything due to my french drain. For example, along the entire perimeter of the inside of my basement there is a 2" or so gap/drain between the foundation walls and the floor (this being the french drain). Now correct me if I am wrong, but if the water table under my house rises above the depth of the foundation (which I am assuming is what happened in this case), wont water enter the basement through the french drain, making it pointless to seal the concrete floor since it will come in anyway?
Another way to think of it is as follows: Think of a cardboard box (resembling a basement foundation), now dip the bottom in a pot of water. The water will seep through the bottom and sides into the box (as like an unsealed basement being flooded). Now if you were to "waterproof" the inside of that cardboard box and dip it in water, it will keep the water out. But now cut slices along the bottom perimeter of that sealed cardboard box (as similar to my french drain) and dip it again, and water will leak back in through those slices. I figured this would be a good analogy of my question. Am I correct on my assumption of the need NOT to waterproof the floor and walls, or do I just not fully understand the workings of this and DO need to waterproof?

I also understand that waterproofing or sealing cant hurt, however, I dont want to spend the money or entire weekend + (a large basement) doing the job unless it is absolutely necessary.

operagost 03-19-2010 11:10 AM

I agree that sealing the concrete probably won't improve the situation. Does your drain have a sump pit and pump? Does it drain far away from the house? How about your gutters?

stadry 03-20-2010 04:10 AM

we wtrproof bsmts &, other'n possible structural damage to the footer, maybe you don't need to,,, eg, we've just had 500yr rains here in ga - some homes flood'd & no amt of bsmt wtrproofing'll ever help those folks as they live in dry lake beds when we get torrential rains.

you've got a ' SLOT DRAIN ' which isn't connected to a sump, gravity drain, OR mechanical discharge ( pump ),,, a TRUE french drain's a pipe-under-floor system according to most who sell/buy/bld 'em,,, far's treating hydrostatic wtr, you may need some laterals under the floor

' Am I correct - assumption - do I just not fully understand the workings of this and DO need to waterproof? ' WHATTA QUESTION - i vote the latter :wink: ' - ok, we'll go 1/2 & 1/2 :laughing: but absolutely necessary ' is your call,,, its going to be tough to edumacate yourself 'cause most every waterproofing ' inspector ' will be a salesman,,, there aren't many who personally watch a job & actually know ' zen wtrproofing ' ! good luck !

buratti 03-20-2010 08:34 AM

Thanks for your input. I know probably the correct thing to do it to waterproof anyway, and I'm not trying to get out of my "homeowner duties" by not doing it, but it'll be a BIG project to do so and its a pretty large basement, so it'll take a lot of sealer. I'm just trying to get other opinions to see if I should, or save the little money and time I have and not do it.

stadry 03-20-2010 04:32 PM

just remember water runs downhill & a sump only means ' collection point ',,, its really fairly easy to engineer a system,,, my 5 guys can get 100' done in 2 days usually & that's w/5gal bkts :thumbup: & 1 bosch brute,,, that's breaking the floor, digging the trench, placing bedding stone, filter cloth, 4" slotted ads corrugated hdpe pipe, cover stone, vapor barrier, & cemento :laughing: have noticed if their native language is english, it will usually take longer :mad:

btw, we ONLY use zoeller pumps ( m53 ) & NO float ( ping-pong ball ) switches - ONLY the slide float on the stainless steel guides !


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