# foundation weep holes for drainage



## shama144 (Oct 16, 2008)

I have completed the foundation for an addition that is 24x30 , 4 courses block and the inspector said as a final approval that I needed to fill the cells of the top course, no problem (done), put 5/8 galvanized steel bolts through the beeam I constructed of 2x10's string together with seams staggered, no problem (done) and finally holes for drainage through the low points of the foundation wall.

That's where I'm having difficulty finding specs on how large or how many I'm supposed to have. I have a code book and there's nothing in there about it but i know I've seen it somewhere and just can't find it again. How big do these holes have to be? And is there a specific type of PVC i should use. I have already located the lo point and drilled three holes angled slightly to the outside of the wall but i want to make sure I don't make the holes too large or too small so i need someone experienced to perhaps site an example or two.

Thanks much!


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## shama144 (Oct 16, 2008)

Hmmm, looks like it's a tougher one than I thought. My code books say nothing about what this inspector is asking of me. I'll just put my 3" PVC through the wall on an angle outward and hope that'll do it.
I still can't find anything out there on this.


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## buletbob (May 9, 2008)

In all my years of building and remolding here in my region I have never seen weep holes installed in a block foundation wall.
I can't see the reasoning behind it, being that the foundation should be water proofed below grade and then a coat of stucco applied over the block foundation from sill plate to grade. Are you sure you understood what he was asking. 
As far as filling the top coarse of the foundation, that was always the norm, you don't want termites working there way up the center of the block. What was his exact request to the issue of the weep holes. BOB


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## shama144 (Oct 16, 2008)

and this is a quote for the denied inspection record
"3) place a drain hole through the foundation wall at a low point"

The entire addition foundation is closed with the exception of two access areas at either end. This addition butts up to a mobile home so the entire foundation must be free standing so it doesn't explain his reasoning. It just so happens that the foundation block will be stucco because of aesthetics mostly and I have a drain pipe that is already installed at the 'low point' of the foundation OUTSIDE the foundation so I'm not sure why he'd expect that water will be under the home enough to require a drain hole through the foundation.

maybe he thought at the high-point which is also the low-point of the existing structure that water would come in the access hole (both access holes match up on the existing and addition for access obviously). I was certain my drainage plan took all this into accomodation since the water will have two way to go around the foundation even if the water comes out of the existing structure at that point because of drain tubes.


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## buletbob (May 9, 2008)

the only reasoning I can see is to keep rain water from collecting inside the foundation until you have it closed in and water tight.
from what you stated that you have already done would seem to me to be of his asking.Let us know what the out come is. when you go for the final foundation inspection ask him what is the reasoning for the pipe. Thanks BOB.


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## shama144 (Oct 16, 2008)

Actually, I planned all those other things. I may be a newbie but it is all very reasonable and as this is the foundation and though i'd like to cut corners where I can, the foundation is kinda critical . the exception is the free-standing. I found out about that by my architect and it is logical. i've actually been doing 'DIY' stuff for quite some time but never done something quite this extensive. I'm paranoid about drainage because we have clay and clay and water are very dangerous mixes on a foundation if the drainage isn't right because the water can't go anywhere and when it freezes, bam! I'm fortunate to have a creek behind the house that the water can be diverted to. I also live in NC so freezing isn't as big a danger as in other areas like in NY where I'm from.

I will ask him about the reasoning and post back.
Thanks


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## buletbob (May 9, 2008)

Interesting! My area is mostly sand and bank run, some spots of clay up on the north shore of the island. So this pipe you had to run through the foundation is for drainage? I can understand running a water proofing into a gravel trench with a drainage pipe wrapped around the foundation diverting the water away would be my thought! Forgive my asking ! I'm curious to know what that pipes purpose is . Thanks Bob


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## shama144 (Oct 16, 2008)

well 'drainage' can really only mean one thing but i don't know where he thinks the water will come from considering it is all enclosed and the drainage around the outside edge should be more than enough to divert it. The access areas still have footing and a single course of block filled at the base so even though water can technically still seep in through the block it shouldn't be so much as to need drainage THROUGH the foundation wall. Heck, nothing will keep it from going back into the crawlspace technically. I would think it shouldn't be done unless there is a problem.
I'll be completing it this weekend and I'll post abck when I call him in to approve the change. I just wonder what kind of other things he'll 'make up' since I see nothing in code about this anywhere.

Thanks


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## Ezekiel (Oct 19, 2008)

I've never heard of an inspector asking for weep holes. I've seen it done to help with wet concrete block basements. Basement repair guys will go along and drill holes at the bottom of the block wall to drain water that collects in the block cells. Then they'll connect these hole to a internal foundation drain that usually goes to a sump pump.


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## buletbob (May 9, 2008)

shama144 said:


> well 'drainage' can really only mean one thing but i don't know where he thinks the water will come from considering it is all enclosed and the drainage around the outside edge should be more than enough to divert it. The access areas still have footing and a single course of block filled at the base so even though water can technically still seep in through the block it shouldn't be so much as to need drainage THROUGH the foundation wall. Heck, nothing will keep it from going back into the crawlspace technically. I would think it shouldn't be done unless there is a problem.
> I'll be completing it this weekend and I'll post abck when I call him in to approve the change. I just wonder what kind of other things he'll 'make up' since I see nothing in code about this anywhere.
> 
> Thanks


Are you located near any water or tidal areas. The only thing I can think of as for the use of the pipe is to allow any water that might collect there during a flood. BOB


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## yesitsconcrete (May 11, 2008)

'weep holes' are holes drilled into the lower block's cells & webs allowing accumulating infiltrating water an escape rather'n build up inside the blocks,,, that may NOT be the definition your inspector follows, tho,,, its a term usually used by waterproofers when installing interior drains leading to a sump & pump.

no code of which i'm aware includes/mentions his definition.


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## Jonestf (Dec 31, 2011)

*Weep holes in Block foundation*

I commend your inspector as being very knowlegdeable. I have found that weep holes are necessary in block foundations. In Michigan we have high water tables of 0 to 15 feet, depending on the time of year.

No matter how much waterproofing applied to the exterior of the block-a high water table will penetrate the waterproofing and hollow block, and ultimately the basement or crawl space. This will cause water instrusion into a basement even with a perfect exterior perimeter drain system. In a short wall crawl space foundation this could cause freezing and foundation damage.

Brick masons always have weep holes in exterior brick to avoid water freezing damage to exterior brick. Foundation builders tend to rely on exterior waterproofing which will always fail in a high water table area.

I have seen many a homeowner spend 5 to 10 thousand dollars on interior drain systems and waterproofing just because the foundation builder did not have weep holes in the block. All they really needed to repair the problem is to drill weep holes through the block to allow the water from the interior of the block to drain to the existing exterior perimeter drain system.

How many weep holes? 1/2 inch hole every third block? (located in the first course of block sitting on the footings) This may be sufficient, but more would be better.


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## TarheelTerp (Jan 6, 2009)

Jonestf said:


> I commend your inspector as being very knowlegdeable.


On that point of knowledgeable... ou should know to look at the post dates.
You have added a comment to a thread that is VERY old; more than 3 years.


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