Why is it that basements aren’t completely sealed for water penetration. My mom’s 2003 house in Maine, and most others I think there, have a hole in the floor for a pump but it also is open to the earth..Now I suppose I get the drain-out idea but its also an entry point for water.. I’m thinking from a boat hull perspective. Why have any hole in a basement for water to get in.. Now, if water comes over the top at the base of your foundation and then into the basement, I can figure that out and pump it out from a depression.. I just don’t understand from my non-contractor/builder perspective why that is.. I’m a boater and would rather pump water out over the top than attempt to remove from a hole in the bottom of the ‘boat hull’ or basement that may just continue to fill when the surrounding earth is saturated….
Thanks for your comments..hopefully not too dumb a question.. 🙂
Mike W
Replies
>>I'm thinking from a boat
>>I'm thinking from a boat hull perspective.
That is the answer right there - nobody wants to pay the money involved in building a watertight foundation and then not be able to take it out for a cruise.....
So how do you build a foundation like a boat? What do you build it out of? You can't exactly fiberglass the outside of the concrete, and concrete alone (even if reenforced) eventually cracks enough to let water through.
And there are load-bearing issues. The force on a boat hull is applied with near perfect balance across its entire surface, whereas a foundation generally bears on footings that are a relatively small proportion of the whole footprint. This could be changed, but then the floor of the basement would have to be very heavily reenforced to withstand the force.
In older houses it was common practice to bring the foundation perimeter drains, sometimes even roof downspouts, inward to the sump pit, which either drained by gravity or pump to a municipal storm sewer catch basin.
"In older houses it was
"In older houses it was common practice to bring the foundation perimeter drains, sometimes even roof downspouts, inward to the sump pit, which either drained by gravity or pump to a municipal storm sewer catch basin."
Until they discovered that bringing water from outside the foundation wall into the basement was a terrible, terrible idea.
>>>Until they discovered that
>>>Until they discovered that bringing water from outside the foundation wall into the basement was a terrible, terrible idea.
Right. I wasn't promoting the idea, just explaining it.
I certainly didn't build my house that way!
I certainly didn't build my house that way!
Sometimes it seems like the builder built ours that way. Only we don't have a sump, so the water just gets into the subfloor ductwork.
(Actually, since we had the furnace redone we do have a sump -- the main plenum for the basement. Since there's no longer a furnace sitting on top of it, I cut a hole in the side of the duct feeding it and installed a sump pump. Covered the hole with clear plastic so we can check on the pump.)
>>>Actually, since we had the
>>>Actually, since we had the furnace redone we do have a sump -- the main plenum for the basement
That sounds like a recipe for long term pain for short term gain. SNAFU.
What do you figure the solution is? Is the grade around your house such that water is shed away? That's the first step.
After that it's a matter of what the water table does. Anything radical?
BTW...to the OP... Didn't mean to hijack the thread. Hope that anything we discuss is relevant.
Let's just say that it keeps us "aware" of grading and other issues around the house. It was a major improvement when we got the driveway slab mud-jacked so that it no longer tilted towards the house. And we use downspout extensions, etc.
Any more it's not a big deal. Since I no longer have to rig a pump to pump out of a floor register, the hassle and worry is mostly gone -- the pump just runs 2-4 days a year (in non-monsoon years), and does so very quietly.
This house was built in 1976, before drain tile was code, and other houses on the block have far worse water situations than ours. And I actually like having the registers in the floor, from a comfort standpoint.
Foundation drains, both interior and exterior , need to drain somewhere. For those homes with drains that can not drain to daylight via gravity, the answer is the sump pump.
The OP said that his mothers sump pit is open to the earth beneath the slab. The current accepted method is to install a sump crock, with the drian tile feeding into it. A properly installed crock will not let ground water into it exccept via the drain tiles. In that respect it is more akin to a bilge pump, to complete his boat analogy.
The purpose of the both interior and exterior drain tiles is to control the ground water by redirecting it. Properly installed foundation drainage will not only manage the direction the water take, but will also reduce the hydrostatic pressure on the foundation. If you have ever seen a an empty septic tank pop out of the ground because of a rize in the ground water level, you know just kow great a force ground water can exert. while a house is much heavier than an empty septic tank, the same principles apply. Without some way of controling all that hydrostati pressure on and under the foundation, it will find its' way into the basement (boat) through cracks and joints.
Last year we had transformer vault completly flood. It shares a common poured foundation wall with the building where I work. In fact our maint. shop is right next to it. The vault had no pump in it. When it filled up our shop wall looked like a multihead shower with the water squirting through every crack and wall tie pentration. while taht was an extreme case, I have seen older home with no foundation drains or poorly installed drains leak so fast that the basements were partially flooded.
It is a whole lot cheaper to install drains and sumps durring construction than to have to retro fit a system afterwords.
Foundation drains, both interior and exterior , need to drain somewhere. For those homes with drains that can not drain to daylight via gravity, the answer is the sump pump.
Repeat - bringing exterior drains into an interior sump and pump is a mistake. If you must pump, set up an exterior sump and pump - do NOT bring outside drainage water into the house.
Repeat - bringing exterior drains into an interior sump and pump is a mistake. If you must pump, set up an exterior sump and pump - do NOT bring outside drainage water into the house.
I can think of few things more miserable than digging through the snow and then dipping your hands in 33-degree water to repair a failed pump in the early spring.
Jeff, can you explain the difference between exterior drain water and interior drian water to me?
Around here it is not uncommon to have both interior and exterior drians. Interior sump crocks are also the most common method used to remove the ground water. This makes the sump pump easily accessable and serviceable. Many are now being installed with baterry back up alarms to warn the HO if there is a pump failure or encroaching high ground water durring a long term power outage.
An exterior sump crock would require some sort of cassing just to install and service the pump. The installation and service cost would be higher, creating a cost that is hard to justify when an interior pump does the same thing. In areas of high radon a sealed interior crocks with a power vents added are being used.
I'm at a loss to understand the difference in where the water comes from and where you manage it makes any difference, but willing to learn something , if you can explain it.
I would love to know about "exterior" sump pits too. At my house, that "pit" would have to be 10 - 14 feet deep as in below the surface of the ground. I have NEVER seen nor heard of anyone putting a sump pit in on the exterior. All exterior draining here connects to the interior lines and pit.
A boat is free to rise and fall in the water, and, as mentioned before, the water pressure on the hull ought to be relatively well-distributed over the surface of the boat.
A house, by necessity, is FIXED in place relative to the ground and (hopefully) is not free to rise and fall with the groundwater levels. Therefore, the hydrostatic pressure on the foundation varies from nearly zero to very high depending upon weather and subgrade variables.
Thus, it makes sense to adapt to varying hydrostatic pressure by:
- waterproofing the foundation wall where subgrade and soil conditions warrant
- establishing a plane of drainage fill (crushed stone) under a slab
- create underdrains or other drainage structures based on known (and anticipated) subgrade conditions
- allow for an accessible water pump-out point (sump) if, and only if, such underdrains and drainage fill cannot be drained to daylight.
Jeff
The other thing you have to consider is that making something absolutely water tight means it will act as a boat.....it will float. There are known cases of swimming pools (concrete) popping out of the ground because they are floating on the water pressure around them. Now I doubt you would ever get enough water to float an entire house out the ground but I can easily see getting enough water to cause the house to "float" several inches up and down which wouldn't be a good thing.