# Sump Pump Pit Location



## theedudenator (Dec 5, 2009)

Is there a typical location to dig and install a sump pump in a basement?

This is the third time in 2 years that the water table has risen above my basement floor. We had lots of snow and quickly warmed temps to 60 degrees.

I want to start by installing a sump pump pit.
When I dig this pit I am hoping I find drain tile.
If not, then I will be adding my own.

How far away from the basement wall?
Corner ok?


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## Bondo (Dec 8, 2007)

> Is there a typical location to dig and install a sump pump in a basement?


Ayuh,... The *Best* place is the Lowest point of the cellar floor....

Mine is in the lowest corner, about a foot from each wall...


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## AllanJ (Nov 24, 2007)

The sump pump pit is put near the foundation wall (often in a corner) because that is where the perimeter drain pipes run or should run.

Not all houses have perimeter drain pipes. If yours doesn't and also you have basement flooding problems, you will have to install such pipes which means digging up all around the foundation down to its footings, your choice of inside or outside.

Retrofitting the house with perimeter drain pipes is usually easier on the inside even though you have to crack up the concrete basement floor.

The first thing to do about basement flooding is to eliminate water pooling up around the foundation outside, doing whatever you have to do including regrading the land.


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## theedudenator (Dec 5, 2009)

I have corrected all outside issues.

My problem is the water table.

The basement was poured in 2001. Hopefully will have drain tile!


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## stadry (Jun 20, 2009)

*hopefully the drain tile's there already collecting the rising wtr table,,, if not, just installing a sump & pump alone can lead to a ' scour ' condition as wtr rushing into the sump can drain & separate the fines out of supporting soils - be careful !*


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## jomama45 (Nov 13, 2008)

Bondo said:


> Ayuh,... The *Best* place is the Lowest point of the cellar floor....
> 
> Mine is in the lowest corner, about a foot from each wall...


I wouldn't be so sure about that. The floor height has little to do with sumps operation. Maybe where you are, the crock can be use as a floor drain as well, but not in most of this country. Typically, it has to be held an inch minimum above the floor so that a sewer back-up will find a drain before the sump crock.

As for the location, it should not matter when connected to a well designed system. Water finds it own level, so it is bound to the crock w/e it's placed, as long as the interior tile (if you have on) is placed somewhat level, an is surrounded by stone.

On edit: One more note: If you're going to end up retro-fitting int. draintile inside the perimeter of the foundation, you need to be cautious when removing the basement floor sections. Most often, the basement floor is an intregal part of the foundation, meaning that it lends support to the bottom of the wall at the footing. If there are no dowels in place between the wall & footing, you really need to brace the bottom 1/3 of the wall when taking out entire sections of the floor to be safe.


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## stadry (Jun 20, 2009)

*location of the crock ( sump - pit ) is largely dependent on ease of operation & shortest discharge - eg, you wouldn't want it in the finished family room if you could place it in the mechanical or laundry room instead,,, for the pump's ease, 8 - 10' head is about max in our practice.

here's our take on jo's monopour or unipour ( slab & footer integrally poured ),,, its very rare on the e coast,,, when we encounter them, we open the floor every 2' for a length of 3' thereby leaving the slab intact & tunnel under the ' holding back ' portions,,, that way no steel is rqd & we have little difficulty placing an uninterrupted collection pipe,,, usually the slab's placed after the house's ' dried in ' in most geographical areas,,, if you've a block foundation wall, measure how much is exposed & subtract from 8" ( height of block ),,, now you know thickness of floor.

leaving the crock 1 or 2 " above floor level's a good idea when possible just as jo notes,,, bracing the btm 1/3rd might be nec IF you're hamming the **** to break the floor - otherwise we rarely see walls that aren't centered on the footer :no:

other than that, for a young guy, jo's pretty good :thumbsup:*


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## Daniel Holzman (Mar 10, 2009)

Monopour foundations are almost unheard of in the Northeast where I live. Typically the concrete on the floor of the basement is thin, typically 2 or 3 inches, has absolutely no structural significance, and is placed only to give the basement a walkable surface. Virtually all houses in the northeast, even old ones, have a relatively deep perimeter foundation that holds up the house, and does not rely on the basement slab for lateral or vertical support.

Down south, it is much more common to see post-tensioned or pre-tensioned slab, especially in areas of expansive soil. In that case, it would be a very bad plan to cut into the slab without detailed knowledge of proper procedures.

As to the location of the sump, as previously noted, the location is not hydraulically important, so long as the perimeter drains tie to the sump location. My sump is in the middle of the basement along one wall, and works fine. You may want to search threads on this website for sump pumps or perimeter drain, as there are dozens of posts relating to the design and construction of perimeter drains and sump pumps.


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## jomama45 (Nov 13, 2008)

I'm not talking about a mono/uni-pour basement floor at all, just the typical floating slab that rests on the footings. There's a reason pilasters are doweled into footings by todays standards. I'm sure all of us (the professionals) have seen a wall shear between the first & second course. The same situation is possible at the footing to first course joint if no bracing is put into place. Of course it isn't common to see any movement at this joint when the floor is only remove for a short period of time, but it also certainly isn't unheard of. It's obvious that there is always heavy, settle, saturated soil present at the base of the exterior of the wall, or else a foundation/drainage repair wouldn't be warranted in the first place. Removing a section of the floor around the entire perimeter is certainly risky in my experience.

As for new const. before the floor is poured? All new foundations, both block & poured, are to be doweled into the footing, or keyed into the footing at the very minimum. As well, the soil is still uncompacted at this point, plus the wall bracing is typically left in place until the basement floor is set-up.


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## stadry (Jun 20, 2009)

*pilasters just for block walls, of course,, not typically being involved w/new residential const, that's good inf for us - thanks,,, we sometimes find grouted walls but they're rare & grout doesn't stop infiltrating wtr leaks,,, 95% of our work's in homes over 20yrs old,,, new home warranty is tyipically 1st yr for wtr in bsmt, etc, as i recall - shirley the result of having attys create warranties :furious:

depending on specific bldr, we'll find 3, 4, & 5" floors - block or conc walls.

in 20yrs, never have that structural problem, jo.*


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## Daniel Holzman (Mar 10, 2009)

Jomama, I am not clear at all what you are referring to. I have been doing structural engineering for 30 years, and have inspected hundreds of houses and commercial properties, and it is EXTREMELY RARE to see a 3, 4 or 5 inch floating slab doweled or connected to the footing. Most of the time they are not even supported by the footing. This is based on several hundred personal inspections of failed houses all over the United States.

Most of the basement slabs I have examined are not even reinforced concrete, and probably half the basement walls are unreinforced concrete as well. If properly built, basement walls are supported entirely by the footings underneath them, and require no support from the slab. The definition of a floating slab is that it is not rigidly connected to the walls, and can therefore "float" up and down with movement in the underlying soil. As I previously noted, most slabs in the U.S. are built this way.

There are exceptions for prestressed and post-tensioned slabs, and sometimes the contractor will build a "turned down" slab where the footing is connected to the slab. This is generally done for slab on grade construction, which is not common in the Northeast, but is common in other parts of the country. Even using slab on grade technique, if properly constructed the footings do not depend on the slab for support, and the slab itself does not depend on the footings for support.

In the case of block wall construction, I personally have never seen the slab connected to the block wall. Since the rods in the block are inside the block, I am not sure how you would connect horizontal steel bars in the slab (if there were any) to vertical steel bars in the block hollows, but perhaps this is done, and possibly this is what you are referring to. I would be interested in the exact method of such a connection, and the reason for it.


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## jomama45 (Nov 13, 2008)

itsreallyconc said:


> *
> in 20yrs, never have that structural problem, jo.*


There could be any number of reasons for that:

- Maybe you excavate the exterior at the same time?
- You're a pro, and only leave the trench open for a day or two, versus the possibility that a DIY'er may have it open for weeks or months.
- Your soil doesn't exert the same loads as we see, or there's more stone present at the bottom of the wall.
- Maybe you've just been lucky?




Daniel Holzman said:


> Jomama, I am not clear at all what you are referring to. I have been doing structural engineering for 30 years, and have inspected hundreds of houses and commercial properties, and it is EXTREMELY RARE to see a 3, 4 or 5 inch floating slab doweled or connected to the footing. Most of the time they are not even supported by the footing. This is based on several hundred personal inspections of failed houses all over the United States.
> 
> That's outstanding. The SE I work with has decade of experience as well, and surely thousands of on-site foundation repair inspections & reports under his belt. Maybe ten's of thousands for all I know, as his specialty if foundation repair. As well, he authored the guidelines in which every local building department accepts for foundation repair in this part of my state. He's no slouch either, and certainly understands the risk that's present when removing entire sections of the basement slab when the lateral forces are at work outside. I'm positive he's seen the repercussions of doing so in the past.
> 
> ...



The foundation/footing detail here is probably the same that you've seen many times before, very typical from my experiences. The only dowels or connections you can depend on being in place with any kind of certainty are between the footing & wall. Nothing tyeing the floating in on a typical foundation. 

Maybe this illustration will help understand what I'm trying to convey:
(Notice the keyway in the pics, it has a function.)










And here's an excerpt about interior drainboard/toeboard from the specs I mentioned:

APPENDIX B

PROCEDURE FOR INTERIOR DRAIN TILE REPAIR WITHOUT EXCAVATION (See also Appendix BB regarding drain tile testing standards)

· Remove floor along wall area (12” to 18” wide) to be repaired to allow replacement of interior drain tile. NOTE: Depending on the exterior ground pressure against the wall, bracing of the bottom 1/3 of the wall may be required to prevent the first course from moving after the floor has been removed.
· Remove existing drain tile and flush with water to sump crock or palmer valve. Check for correct drainage. Check with local jurisdiction if palmer valve is permitted (per local requirements).
· Replace drain tile at floor removal area with polypropylene drain tile and encase new tile with proper filtering stone.
· Drill one (3/4 to 1 inch) drainage hole into the bottom of first course per core, under floor line, for block drainage. Holes shall be cleared for proper drainage.
· Wall drainage board shall be a one-piece unit. Wall drainage board to be installed at least 1” minimum higher than finish floor height and against first course to assure unrestricted passage of water flow. The wall drainage board MUST provide lateral support to first block. Wall drainage board must be able to be sealed off to provide radon mitigation if necessary.
· Test wall drainage board: Drill holes at the third to fourth block above the footing and every 3 to 4 feet horizontally for the entire wall where possible. Flush wall with water by inserting hose into injection holes. Check for unobstructed flow to wall drainage board by observing water flow at the base of the wall.
· Replace floor where removed. Minimum thickness not to be less than 1” from existing thickness.


It's not that I don't think a repair like this CAN'T be done w/o bracing the bottom of the wall, it's just that I don't think it's responsible to tell DIY'ers that it not a concern at all.


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## stadry (Jun 20, 2009)

*reasons - usually interior systems are recommended & selected due to ( diagnosis-extent of issues-$ in client's pocket :thumbsup: ),,, do open/close most same day,,, soil loading's probably comparable due to georgia's hi clay content,,, rather be lucky than good :laughing:

keyway noted - who wrote the specs, jo ?
* Remove floor along wall area to accommodate shovel's width;
* palmer valve - is that the 1 operated by the sprenkle wrench ?
* typically, we try to slope the drainage piping 1" in 10' - problem occurs over 80' where the pipe's elevation comes close to footer btm & may encourage scour,,, when that occurs, the solution's a 2nd crock & pump;
* 3/4" drain holes in ea cell AND web junction;
* filter cloth excavation liner;
* # 57 bedding & cover stone;
* 6mil vapor barrier;
* 3,500# 3 - 4" ( as rqd ) replacement conc.


whoever told diy'ers anything - they're like my kids - already know it all *


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## Docwhitley (Jul 19, 2010)

If I need to install a new Pit and drains I like to try to put the pit near one of 2 locations

1- Water Heater- Stole this from a customer that had one in his Water Heater room when it began to leak. It apparently was pumping water all day and the Sump pump that he had was able to manage most of the water.

2- Near Laundry machine- Just in case a hose breaks


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## godmaf (Oct 5, 2021)

Daniel Holzman said:


> Monopour foundations are almost unheard of in the Northeast where I live. Typically the concrete on the floor of the basement is thin, typically 2 or 3 inches, has absolutely no structural significance, and is placed only to give the basement a walkable surface. Virtually all houses in the northeast, even old ones, have a relatively deep perimeter foundation that holds up the house, and does not rely on the basement slab for lateral or vertical support.
> 
> Down south, it is much more common to see post-tensioned or pre-tensioned slab, especially in areas of expansive soil. In that case, it would be a very bad plan to cut into the slab without detailed knowledge of proper procedures.
> 
> As to the location of the sump, as previously noted, the location is not hydraulically important, so long as the perimeter drains tie to the sump location. My sump is in the middle of the basement along one wall, and works fine. You may want to search threads on this website for sump pumps or perimeter drain, as there are dozens of posts relating to the design and construction of perimeter drains and sump pumps.


I am a structural and geotechnical engineer who works in the northeast. The slab is bracing the bottom of the foundation wall laterally, which is reliant on the bracing top and bottom rather than being designed as a retaining wall. Your footing will be a strip footing rather than a wide retaining wall footing, and there are no (or very few) vertical rebar in that wall. The slab is also placed over a vapor barrier, preventing pest and water intrusion (called a sanitary slab or rat slab where used for no other purpose, such as a crawlspace).
see table 3 note g: Searchable platform for building codes


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## chandler48 (Jun 5, 2017)

@godmaf Glad you could pitch in. Even if it was 10 years after the fact. Check the dates for more concise information and posts.


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