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polihronis 10-16-2006 03:29 PM

I've an 1,800 sf floating basement. What's the correct size of a sump pit?

Ron The Plumber 10-16-2006 05:38 PM

Code book dictates the size pump, and depends in fixtures units dumping into it. pit size will very, not knowing the info and where you live, we can not even attempt to answer your question.

polihronis 10-17-2006 08:03 AM

Currently the basement has a sump pit approximately 14 inches by 14 inches (State of NJ). It's constructed out of a cement cylinder, bottomless and no perforations. When it rains, initially it takes a couple of hours , then the sump pump (1/2 hp) operates continiously, at times if the rain is heavy, there's water accumulation on the opposite corner of the sump pit, it's not very much, but prevents me from being able to finish the basement. In addition there's spot of mold on the walls (2 feet high from the floor). A couple of years ago the basement was completely dry, therefore i went ahead and put dry wall and heat baseboards , only to have the moisture problem resurface recently.
People that i know with good knowledge of basement problems, have indicated to me that a larger sump pit at the point of water accumulation could indeed take care of the problem.
Could some one advise as to whether this is true or a different approach for fixing the problem must be taken.
Very appreaciative

Ron The Plumber 10-17-2006 08:11 AM

What size is the line used to pump the water out with? Is there a check vavle on the line just above the pit?

polihronis 10-17-2006 10:43 AM

I'm not very knowledgable about these things and that's why i'm asking the questions! The pump is connected to PVC pipe (2 inch diameter) 5-6 feet long (going up vertically) and out the basement wall, i don't know if there is a check valve on the line just above the pit. From the person tha installed the pump in the pit , i remember him saying the he installed a check valve in the base of the pump. Is that what you're reffering to?
Aside of that though the question is very simple, given the small size of the existing sump pit for a 1,800 sf basement, should a larger sump pit, and more spicifically deeper , be installed to cure the problem?
Thanks again

Ron The Plumber 10-17-2006 06:30 PM

That would be the check valve, a 2" outlet on the pump should handle all the water entering the pit, have you always had this problem?

Maybe a larger pit is needed, what do you have a river in the basement?

Also check the float, might be set too high in pit, if so lower the float so it will kick in sonner.

crecore 10-17-2006 08:42 PM

either your water table is high or you have insufficient or no perimeter drain. My house is in clay soil and my pump has run once in three years when I ran a water hose into the pit for three hours and plugged in the pump. :thumbup:

polihronis 10-18-2006 08:11 AM

The subterrenia i'm positive is clay, water table level? how can someone determine that? and if so what can you do about it? In terms of perimeter drain, the only thing i know, it's a floating basement!
So again, the depth of the sump pit is unequivocally insufficient, i don't want to do the french drain right now, would lets say a 3-feet deep by 24 inch wide sump pit aliviate the problem? Any suggestions as to what should i do next???
Thanks in advance.

Ron The Plumber 10-18-2006 08:16 AM

Where does it drain to, is this an open pipe that the water flows from and is it clear of debrie?

At what point does the float start the pump?

concretemasonry 10-18-2006 08:58 AM

You will not be able to finish your basement until you get better drainage (drain tile) in the areas away from the sump. If you have a mosit floor area in the opposite corner, you can be sure you have a lot of hidden water in the soil and walls in that end of the basement.

Your sump is working as designed, but it just cannot collect the water from the entire area. A bigger pump would empty it faster, but would not have an appreciable effect on the water table around your basement.

Since you have a heavy soil, the exterior of your house is very important since you want to get the water away. Make sure you have gutters and long (8'minimum), downspout extensions and positive drainage (away from the house). Make sure your sump pump discharge drains well away from the house. All this is much cheaper the the next step (drain tile), but all are DIY projects.

A definition of a basement is a concrete box that builder put in a swimming pool without a drain. It is far easier, cheaper and more reliable to drain the water away that to try to waterproof.


polihronis 10-18-2006 10:34 AM

Very appreciative for all inputs; they've shed a lot of light. Please explain the "drain tile" and how is it different and/or more effective than the french drain? and what would be an approximate cost?
NOTE: My neighbors , left and right have basements but do not have the water table problem that i appear to have? is this possible?

polihronis 10-18-2006 11:06 AM

The float is set approximately 10 inches from from the bottom of the 14 inch deep sump pit. The water is pumped away from the foundation.

concretemasonry 10-18-2006 03:35 PM

polihronis -

Often the terms "french drain" and "drain tile" are used interchangeably. however, some "french drains" do not use actual drain tile, but only clean sand, pea rock and rock. It is a matter of terminology. I was speaking of removing a strip concrete along the wall in the basement and digging a trench down to the bottom of the footing. The trench is filled withsome rock, drain tile, more rock and then capped with concrete level with the slab. The drain tile would lead to a sump where the water is collected and pumped out. It is usually pumped into a storm drain or out into the yard far enough from the house, so it will flow away.

If your neighbors do not have a problem, there must be a difference.

Assuming all homes have the same native soil, some possibilities are:

Difference in basement elevation
General grade toward your home
Better control of surface rainfall on the lot and from the downspouts
Different backfill
Different excavation method/pattern for the basement

Next time it rains go outside and take a close look at where the water goes. This is where to start.

If you have water on the floor and mold up the wall, I would not finish off the basement until I was sure that I had a long term solution.


Ron The Plumber 10-18-2006 06:26 PM

Sounds like the pit is undersized, go with a larger pit install a barrel like seen in the link below.

747 10-18-2006 11:56 PM

exactly also make sure you put some kind of mesh in the barrel this will prevent the pump from getting clogged with debre. A perimeter drain might not be a bad ideal either. This is a drainage system which runs around the foundation on the house(outside) underground keeping water away from the foundation.

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