water in basement problem

[dee2]

water is seeping into corner of basement bedroom.  appears to be groundwater coming up through joint where the floor slab meets the foundation wall. Floor slab sits on top of foundation wall footer.

I assume there is some hydraulic pressure below the slab from the fact it is rising up into basement, even though the outside wall daylights. The water must be trapping itself under the slab and finds the interior of the basement before the outside ground.  The outside ground slopes away from the house, starting elevation is top of footer.

My Plan:
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I don't want a sump because this is a bedroom.  I hope to drillholes through the foundation wall at the top of the footer near bottom of slab so it can  drain out.

My question:
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Is this acceptable ?

[glenn kangiser]

Welcome to the forum.  Depends.  Hydrostatic pressure can develop around plugged drains or improperly built drains around a basement wall also.  This head pressure then looks for the first available opening with less pressure to dump into.  Your holes may allow more in. 

First I would look around the house and see if there is a reason that it is building up pressure and coming in.  Gutters dumping near a wall -- hillside drainage not directed away - gopher holes etc.  Get more info for us and we can talk more about it.

[MountainDon]

I think holes like you propose would simply provide an easier ingress of the water.

I had a similar problem years ago. The contributory cause was mainly rain or melt water running towards the house wall instead of away from the house. The sidewalk there actually had a slight towards the house slope. Removing the old walk, adding fill and pouring a new walk solved most of the problem. There was still some seepage in the spring when the snow melted.

As Glenn, said,  and more details about the lay of the land, etc might help.

[dee2]

The holes would be above ground, open into the air, so water could not get in from the outside.

I hope to do more preventative drainage work on portions of the walls below grade, but that may not be until things dry out and no assurance if  I will be successful.

These "weep" holes were intended to achieve drainage in either case.  My concerns are if I will be violating any standards.  I know there are utility type knockouts placed through walls so I thought small weep holes would be allowed (?)

Hard to describe lay of land...

Corner with leak is on NE point of house.  North side is below grade approx. 6 ft of depth, new clean gutter above, roof slopes to North.

East side of house is open to air because of north-to-south retaining wall 4 ft east  from building, providing a walkspace along east side of building.  Walkspace slopes to south for drainage.

south side of house is daylight basement.

[MountainDon]

The holes would be above ground, open into the air, so water could not get in from the outside....
...Corner with leak is on NE point of house.  North side is below grade approx. 6 ft of depth

I'm having trouble following that. Picture? Drawing?

Maybe it's just me?    Sorry if I'm being dense today.

I picture the leaking area being below grade if water's leaking in. I'm not sure how you mean the holes would be above ground and help the problem? 

[dee2]

I couldn't begin to draw this...

the north side is below grade, the east side is daylighted because of retaining wall 4 ft to east of house

[glenn kangiser]

I wouldn't worry about violating codes or structural integrity if the holes don't go through any rebar.  Many contractors I have seen don't even worry about that, although rebar is very hard to get through with a concrete bit.

I assume it will not be inspected anyway?hmm

[dee2]

 I don't think I'll hit any rebar. 

I'm envisioning only a couple of half-inch diameter  holes , 9-in deep to insure I get through the wall and reach the vertical portion of the joint.  i won't be seeking  permit for a couple of holes.

These would be horizontal and at the top of the footer so they are close to the bottom of the floor slab.

My  hope is the water seeks/finds the holes before pushing up to the top of the basement floor.

[MountainDon]

I almost don't want to mention this next thing. It could very well cause problems, maybe even bigger problems. It could be possible to seal up the joint where the water is entering. The potential problem is sealing up the crack will just increase the water pressure. This could make the problem show up somewhere else, maybe in a more serious manner. 

Look for hydraulic cement. Works wet too.

[glenn kangiser]

I have a better picture of what you are doing now.  It may work.  After you are done you could try to open a drainage path with a long rod or electricians long stem drill.

[dee2]

... It could be possible to seal up the joint where the water is entering. ...

I did consider this, but I know that I would likely find the leak has moved down the wall to another location or, as you noted, it could simply push the floor upwards causing cracks in the slab.

It's also very hard to get to as the walls are finished and the wall/floor joints on the inside wall are covered with 2 horizontal, 2x2 firring strips (stacked vertically)  across the wall/floor joint which serve as a base for the vertical firring strips on 24-in centers.  I would need to tear them out which likely means removing most of the drywall...

[ScottA]

You don't have any leaking pipes under this floor do you?

[dee2]

You don't have any leaking pipes under this floor do you?

fortunately, there are no pipes or utilities under this floor

[JRR]

Is there some reason you would not want to go ahead and dig a surrounding drain path, and also to reshape the ground above?  I kinda doubt the water under the slab needs your added holes to find it's way downhill.

But hey, it may work!

[dee2]

So far the water under the slab seems confused as it did come up into the basement.

I'm adding a piped trench today to the North side ground above.  The length I've trenched so far seems damp from the recent storm event, but not wet, so I suspect it will not offer much benefit. 

The dirt right next to the wall is dry due to the roof overhang protection.

I don't actually know if the holes will help either.

[glenn kangiser]

Please keep us posted on what you find.

[dee2]

Please keep us posted on what you find.

Progress Report
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I enhanced the surface drainage controls outside the North side of the house by sloping the ground 3-4 ft away from the house, placing some plastic sheeting on the ground and feeding it into a piped trench which drains away from the building.

I then bought a 1", SDS, rotary-hammer drill and drilled a 1" diameter horizontal hole above the footer 1' deep in towards the basement floor.  Inside the basement room I drilled a 1" diameter hole vertically down through the floor to intersect the horizontal drain hole.  I made a connection.

Adjacent to the vertical hole, into the room, I  opened a 4"w X 12"l X 6"d slot in the floor.  I inserted a "tube" of screen partially into  the drain hole inlet to keep it from plugging.  Then I removed an additional 2" of soil below, which I replaced by filter wrapped gravel to a height 1" above the screen. The idea is to get the water to migrate to the gravel before finding the floor-wall joint.

With that in place, I finally put some  1" OD tubing into the drain hole I drilled so water would be carried away from the footer.

For now, I've left the floor slot open so I can observe what is happening from any upcoming rain events.  The 2" of clearance from the top of the gravel to the top of the floor will eventually be backfilled with concrete.  I will separate the gravel from the concrete with plastic sheet.

Actual results were observed during this last week which had several days of light to heavy rain and so far things inside have stayed dry.  Water fills the slot to within 2" of the top of the basement floor with a constant weep through the drain hose. Drain flow rate was measured at about 3-4 gallons per hour.

At this point the only other thought would be to extend the "gravel catch basin" parallel to the wall to further insure water will always find the gravel before the floor-wall joint.

[glenn kangiser]

Looks like you are gaining on it -- thanks for the update.