Hi,

I’m in the process of installing an interior perimeter drain in my basement. My walls are concrete block and I was having a problem with water seeping out of the lower courses of blocks after heavy rains. I’m doing the work myself.

Here’s what I’ve done so far…

Removed a section of the floor about 14 “ wide along the perimeter of the basement to expose the footing.
Dug a trench along the footing that slopes gradually towards a sump basin. Trench approaches the sump basin from two sides.
Drilled ¾” holes into each of the block cavities (2 per block) in the course of blocks that sits directly on top of the footing. Water now comes out of these holes when it rains.

What I yet have to do…

Place 4” corrugated and slotted drain pipe in the trench and run it to the sump basin.
Run 1 ½” PVC pipe from the sump out of the basement to drain the collected water into the storm sewer.
Cover pipes and top of footing with gravel.
Replace floor with fresh concrete, leaving 1” space at the wall.

What I’m looking for is feedback on what I’ve done and what I’m planning. Is there anything that I’ve done wrong, or should watch out for as I continue this project?

Also, I seem to feel that my corrugated drain pipe should be slotted on the top and sides, but should have a non-slotted section on the bottom that will allow water to flow through it, but the only slotted pipes I can find have slots situated all around them. Am I correct in my assumption about what I need, or will what seems to be the standard in slotted, corrugated pipes work?

Thanks,

David

 

NJDave,

Try these, they should help but it sounds like you're doing ok. The drain tile issue though is simple - SLOTS GO DOWN, NOT UP. Sounds like you got the wrong tile.

http://www.jlcnet.com/banner/basep4.html

http://www.usinspect.com/Crawlspace/PerforatedPipe.asp

http://members.aol.com/karlmyles/tile.htm

Hope this helps!

 

Doug,

Thanks for the reply and the links.

The drain tile that I have has slots all around. I can't orient it so that most of the slots are either up or down. What I was asking before was, should I try to find a drain tile that does have a section where there are no slots? From what you're saying, it sounds like this type of drain tile does exist. Is this correct?

I don't understand why the slots should face down however. It seems to me that the water should be able to enter the drain tile from above, then flow down the tile to the sump. If the slots are facing down, wouldn't any water that gets into the tile just seep out of the slots, and never get to the sump?

I appreciate your help.

David

 

NJDave,

I'm not sure where you got your stuff at but Home Depot does sell the Corrugated Drainage Pipe with just one slot and as I mentioned this is to be placed with slot down. This method is used to prevent it from being blocked with any silt and the like that could clog it. In addition, you want to be able to get water into this pipe as soon as water is close to it, especially from below. In some cases, waiting for the water to get to the slots on top might be too late. I was told that having the slots up is incorrect but I thought this was referring to the exterior applications only...wrong. For those that do get tile with slots all the way around, you could lay felt paper over the top and then cover up with pea gravel but I would get the one with slot on bottom only.

There is the issue of sloping the pipe to the sump pump but lets face it, you don't need much slop if any as the 4" pipe is large and if you are having a FLOOD that would fill this up, I'd buy a boat!

Hope this helps!

 

Doug,

The Home Depots near me (I've been to three of them) all have two types of corrogated 4" pipe. One has no slots, the other has slots all around.

Just to make sure we're talking about the same stuff, these pipes are flexible, black and come in 100' rolls, or 10' lengths. They also sell what looks like a 4" PVC pipe (white) with one set of holes drilled along one side. This white pipe is not corrogated and is not flexible.

Back to the positioning of the slots...

My water problem seems to come from the concrete block walls. In my mind it would seem that the water will be entering the drain pipes from above, this is why it seems to make sense to me to have the slots facing up. A non-slotted section facing down would then allow the water to have a channel to flow to the sump. If the slots were facing down or all around, why wouldn't the water just would pass through the pipe without ever getting to the sump?

I'm getting confused!


David

 

Here is my 2 cents, but I have been wrong before so check it out.

I would put a layer of stone in the bottom of the trench and lay the pipe on top of that.

In the case of the slotted and corrugated pipe (4" I think) I would use the one that has a "sock" over it - this acts to prevent silt and such from getting into the pipe. The "sock" or filter is synthetic so will not break down over time.

In the case of the rigid PVC (either 3" or 4") with holes - place the holes down. As the water level rises it will fill the pipe and get taken away to the sump. If you place the holes facing up then the water level will have to cover the pipe before any enters to be taken away to the sump.

The drainage from the block wall is not simply going into the pipe, it is going into the trench and that is what the pipe (corrugated or PVC) is draining to the sump.

 

Doug and PenguinDave,

Thanks for the replies. You've both given me something to think about.

One last question for all...

Does anyone have any good/bad thoughts on the sump pumps available at Home Depot? I had heard that Little Giant was a good brand of pump, but I think the Home Depot brands may be less expensive. Not looking to skimp on my project, but sometimes my cheap side comes out.

Thanks,

David

 

I installed a perimeter drain in my house using virtually the same plan you have described. Works great.

I used the corrugated flexible black 4" tubing with the slots all the way around. I did not use a "sock" around the tubing. What appeared to be more important was to be sure to have pea gravel on top and to the sides of the tubing so that the concrete I used to fill the gap did not get into the tubing.

By the way, I did not leave the 1" gap around the perimeter but went all the way up to the cinder blocks.

Seven years later, no water.

 

indianabc,

Thanks for the feedback on your experience! This is the best way for water problems alsthough many try to do the coatings and over time they have failed. For those that have done this only and then finished their lower levels, you really don't know what is happening behind the walls now but just keep your fingers crossed.

Just for curiousity sake, did you waterproof your walls at all prior to ar after installing your drain tile? The reason I am asking if you did not, did you have problems before with damp walls? Are they dry or drier now?

I don't know why some think that the 1" gap is required when installed this system. It is not required and doesn't do anything. Your comments on this?

 

doug,

We did try waterproofing "paint" prior to the perimeter drain but it just made the walls drier, the water still ran down them to the floor, you just didn't see it.

However, it did seem to make the area a little better once the perimeter drain was installed, although we still have a dehumidifier in the basement.

 

Doug,

My interior drain project is finished except for the last step of pouring concrete to replace the floor. All the wet weather we’ve been getting in the Northeast has been a great test for the system, and whaddya know, it works!

I like your idea to not leave a gap between the floor and the wall when you pour concrete. It makes sense to seal the water in rather then leave a space where moisture can escape. That leads me to a concern that I still have about my basement.

Even with the interior drain, there are a few damp spots that develop on the wall above where I’ve drilled weep holes in the block. These damp spots tend to dry up over several days once the rain has stopped, but I’m worried that once I finish my basement with stud and sheetrock walls that these damp spots may not dry as quickly and could promote mold growth.

Should I apply Dri-Lock or some other sealer to the walls? I’m also thinking about coating the walls with a layer of mortar (I think it’s called a parge coat, or something like that). Is this overkill or a good idea? I don’t mind doing some extra work to help insure that I don’t have a mold or moisture problem later on.

Thanks for your help!

David

 

David,

I would apply Drylok and be done with it. This product is good as long as other things are done and that you have done with your drain tile installation. Once this is on the walls, you will virtually eliminate any dampness and if any is present will dry up and the issue of mildew/mold is eliminated.

As you have seen in previous posts on how the walls should be framed and placed 1" from the wall, this does allow for ventilation so it will dry out. Mold and mildew to grow needs constant moisture, no ventilation and organic material. Eliminating 1 of these is a step in the right direction! You should have no problems at all!

Good luck!

 

Saw an installation using a platon membrane product the other day that I really liked. See the the "Internal Leakage Repair - Major Retrofit" diagram for a picture of the installation I saw.http://www.systemplaton.com/drawings.html

This product is the dimpled product on the bottom of DriCore, just in roll form. It is available here in Canada at Home Depot, I think the same is true in the US. The site lists locations I think.

Basically the bottom part of the wall had the platon applied to it, the platon made the 90 bend at the bottom and extended over the installed interior drain tile, then the concrete was poured over the platon and the floor finished. Result is that any water that does come through the wall flows down the wall into the drain tile system.

 

When the Pros did mine, they covered the channel ( pipe) with gravel, then put down clear plastic on top of it all before pouring concrete. They also put in a couple of clean out (access) pipes so I can flush out the system if needed.