# Drilling weep holes in basement wall



## tom_poconos (Nov 6, 2017)

I'm working on a basement drainage system and I explained my approach to another DIYer. Their recommendation was *not to add weep holes* to the block wall, as it could invite new problems. They argue that if the wall has been standing for 50 years it's not going to cave in now from hydrostatic pressure. He just recommended re-applying waterproofing and see what happens at the next snow melt. I've already excavated the trench and sump pit, so am pretty invested in the traditional approach of trench + sump + weep holes. 

My argument is not addressing the problem properly could lead to a structural issue at some point (though he is right, the wall has stood for 50 years). Also, adding weep holes would control the leaks predictably, so I wouldn't need to worry about new leaks springing up where I haven't waterproofed.

Any thoughts on this?

Bit of background: 1 wall in our basement leaks after heavy snow melt and rain - there are about 5 points across the wall that leak. It's a weep in most places but more than a trickle in others.


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## XSleeper (Sep 23, 2007)

Yes, you generally put weep holes _below the grade of the slab_ and a drainage/ air gap membrane (before you repour the floor) that leads to your trench drain which leads to your sump pit. The idea is to let any water inside the cmu out rather than letting it build up and find its own way out. (Which might otherwise be ABOVE the slab)


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## TarheelTerp (Jan 6, 2009)

tom_poconos said:


> 1 wall in our basement leaks *after heavy snow melt and rain* - there are about 5 points across the wall that leak. It's a weep in most places but more than a trickle in others.


What have you done about downspouts, runoff leaders/pipes
and of course positive drainage away from the foundation?
Until these measures have been exhausted do nothing else.

Next up is that the OUTSIDE of the wall is still where the remedy goes.
Keep the water away from and out of the walls & basement.

The idea of tearing out 50 years of developed shrubbery is daunting.
It's probably the best selling point for the inside approach you've begun.

Here's a LINK to some pictures about it.



> ...recommendation was *not to add weep holes* to the block wall,
> as it could invite new problems.


Taken that far he's mostly correct.
Keeping water OUT of the wall is the objective,



> He just recommended re-applying waterproofing


Nope. All that accomplishes is keeping the water in the wall.
And it rarely does that well in any case.



> My argument is not addressing the problem properly could lead to a structural issue at some point ...


The structural issue to worry about is washing out the packed soil below the foundation. The inside trench and pump method has risk here.
---


> I've already excavated the trench and sump pit, so am pretty invested in the traditional approach of trench + sump + weep holes.
> Any thoughts on this?


It works. I've done it on two different houses.
But these both had rising water table issues not runoff penetration.


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## tom_poconos (Nov 6, 2017)

TarheelTerp said:


> What have you done about downspouts, runoff leaders/pipes
> and of course positive drainage away from the foundation?
> Until these measures have been exhausted do nothing else.
> 
> ...


We will address the issue from the outside in spring. Bit hard right now. All I can do is manage the water in the basement and it's either weep holes or waterproofing. 

I have not actually excavated a trench along the leaking perimeter. I have just excavated a 2 foot wide hole at the lowest point in the slab for the sump basin (it's 6 inches from the leaking perimeter).



XSleeper said:


> Yes, you generally put weep holes _below the grade of the slab_ and a drainage/ air gap membrane (before you repour the floor) that leads to your trench drain which leads to your sump pit. The idea is to let any water inside the cmu out rather than letting it build up and find its own way out. (Which might otherwise be ABOVE the slab)


Would it be a really bad idea to drill very small weep holes above the slab, into the first row of blocks (since I have not excavated the perimeter and have no access to the below grade blocks)? I am fine with the water leaking onto the slab, it will run straight to the basin, as I will build a concrete berm.


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## TarheelTerp (Jan 6, 2009)

tom_poconos said:


> I am fine with the water leaking onto the slab,
> it will run straight to the basin, as I will build a concrete berm.
> 
> Would it be a really bad idea to drill *very small weep holes* above the slab, into the first row of blocks (


That's an interesting approach to the job.

The holes need to be big enough to not clog with debris.
I've never seen less than a 3/8" or 1/2" drill used.


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## tom_poconos (Nov 6, 2017)

I guess I can always plug the weep holes up with hydraulic cement if adding them creates more issues.


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## XSleeper (Sep 23, 2007)

How exactly do you have a trench and sump pump but you haven't exposed the footing or bottom course of block? And you want holes above the slab so water can run out onto the floor? What kind of a drainage system is that?!? No. Just no.


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## Bud9051 (Nov 11, 2015)

Hi Tom, maybe I missed it, but what is your objective? Are you just managing the moisture or are you planning to finish this basement into living space? Converting a wet basement to living space is high risk and expensive.

Bud


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## tom_poconos (Nov 6, 2017)

XSleeper said:


> How exactly do you have a trench and sump pump but you haven't exposed the footing or bottom course of block? And you want holes above the slab so water can run out onto the floor? What kind of a drainage system is that?!? No. Just no.


Why the hostility? This is a DIY forum... obviously there are going to be some unconventional approaches. 



Bud9051 said:


> Hi Tom, maybe I missed it, but what is your objective? Are you just managing the moisture or are you planning to finish this basement into living space? Converting a wet basement to living space is high risk and expensive.


It's an unfinished full basement. Definitely never going to be a living space. Just need to manage runoff that occurs only after heavy rain and snow melt. It's not a water table issue. Currently, water leaks out of one perimeter wall. Previous owner did some waterproofing. I don't want to excavate a full perimeter trench and do gravel and perforated drain pipes etc. I just want a closed sump basin (no perforations or inlets) that is flush with the surface of the slab and a berm/lip running along the leaking perimeter that holds in the water as it *cascades* into the basin. Not concerned that it may be ugly or unconventional, just want it to work. I understand that exterior work is the first thing that is necessary but we just bought this house and it's the middle of winter.

Thanks


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## XSleeper (Sep 23, 2007)

What you interpret as hostility is not. It is good intentioned advice... take it or leave it. Your house. You asked for advice- some of us are professionals. There are some things a professional would not do or recommend doing. Right way, wrong way. Do it how you like. And have fun doing it. I'm not offended if you don't like the advice that's totally up to you.


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## tom_poconos (Nov 6, 2017)

XSleeper said:


> What you interpret as hostility is not. It is good intentioned advice... take it or leave it. Your house. You asked for advice- some of us are professionals. There are some things a professional would not do or recommend doing. Right way, wrong way. Do it how you like. And have fun doing it. I'm not offended if you don't like the advice that's totally up to you.


What is wrong with my approach? It's essentially the same concept as these commercially available solutions:

http://waterproof.com/sealonce-diy-basement-waterproofing-system/
http://basementwaterproof.com/

Obviously not ideal, but I'm not building the Taj Mahal here. I just want it to work, be lawful and be cost effective. Additionally, I don't want to invite further problems. This approach is less invasive than a full perimeter trench. And again, I can't do outside work until spring. Need to solve this problem from the inside as best as I can during winter.


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## MTN REMODEL LLC (Sep 11, 2010)

Tom,,,Given your considerations, I don't think it's dumb or likely any structural issue.

You would be effectively reducing your hydrostatic head/pressure and controlling the interior water migration.

I haven't actually seen it in years, but there used to be, and maybe still is, a manufactured channel system designed primaarily for damp/weeping basements that was almost an upside/ down gutter that sealed against the wall and the slab, with drilled weep holes at about the cold joint of footing-stem to slab... with the gutter dumping into an interior sump.

The idea was to control the hydrostatic build up behaind the wall, and seal and deliver the drainage/weepage to a controlled sump pump.

People were finishing their basements under those conditions.

As good as good perimeter exterior systems and good exterior waterproofing... NO.... but a pragmatic compromise in many circumstances.

Good luck

( I had in my personal home a below grade work/storage room I had added 
It was built against an existing stem wall and although I had a french drain under the new slab, and I thought a well waterproofed cold joint at the wall connection, I had nominal leakage/seepage at the cold joints under very heavy sustained rainfall or quick heavy snowmelt.

It only occured 3 times in 20 years, and my work/storage area was controlled by some heavy rags for a few days..... BUT,, had it been a finished basement, a controled channel would have been a perfect/pragmatic solution.

Because of the structural considerations and site considerations I had worried/anticipated the possible occurance, and had my whole slab with a 1/8 kant to one corner if I ever had to put in a sump.... but it never got that bad.

Guess my point is that while exterior solutions are best, but not always possible or pragmatic, there are other ways to mitigate/solve the issue as I think TOM POCONAS is trying to address.

Good luck.... Peter


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## tom_poconos (Nov 6, 2017)

MTN REMODEL LLC said:


> while exterior solutions are best, but not always possible or pragmatic, there are other ways to mitigate/solve the issue as I think TOM POCONAS is trying to address.
> 
> Good luck.... Peter


Much appreciated, thank you. Those channel systems are still available and that's where I got the idea, if I recall correctly. One is called Beaver Basement. One drawback I could see was if the weep holes get blocked you need to rip the channels up, else the wall will start leaking at random places again and trickle over the gutter.


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## COLDIRON (Mar 15, 2009)

Yo Tom, so far I have never seen an interior approach to solve water problem coming from the roof or foundations.

If only if you can wait till Spring. I would recommend a foundation exterior drain field. Just a small trench on the exterior of the foundation with perforated PVC covered with cloth to prevent silt and stones entering. Directed away from the foundation. The best approach is to stop the water before it even gets near the foundation. Hey, if you can't wait or you don't want to it's your place and your call. Good Luck whatever you decide.


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## Nealtw (Jun 22, 2017)

If water is left in the block it will find another way out and into the area, I would drill holes. and curtain the wall with dimple board down and over the drain tile.


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