I’m building a house with a full foundation on a flat lot with very sandy soil. The seasonal high water table is > 10′ below grade. Conventional wisdom (and the foundation contractor) says to always put in drains at the footings, pitched to daylight (a very long run in my case).
I question the need for drains in my situation, however. My reasoning is that any water in the soil will just go straight down past the footings. There is nothing to divert or hold the water (no clay, rocks, etc) just pure sand. I’ll waterproof the walls, of course.
Am I off base with this reasoning?
Replies
If you ever need one later it will cost 10xs as much to put it in as it will cost you now.
If it were my place, I would bite the bullet & install one. Water has been known to do strange things. Maybe a drain on the inside of the footings ran to a sump pit. If you ever see water in the pit you could hook up a pump & have 1/2 the battle won!
Good Luck with the Project!
I agree. Put the perf pipe along the foundation, and run it to a pump sump. Leave outr the pump for now. You can activate it later for just a few hundred dollars, but if you need to add the pipe later, it's a killer. Several discussions here about people discovering that they have water problems, and they are looking for alternates to not trenching for perf pipe.
I'm sorry, I thought you wanted it done the right way.
Point well take. I'm planning a sump pit anyway - now I'll consider adding the perf pipe.
Have your builder form the footing with Form-A-Drain. He'll never go back to wooden forms and using perf. pipe.
Form it, pour it,pull the stakes, filter fabric, crushed stone and your done. Takes the place of inside and outside perimeter perf. pipe It stays in place, so his form wrecking and cleaning cost offset the slightly higher cost of the system. Just follow the instruction in the suppliers lierature.
Go to http://www.cerainteed.com for a look see.
Dave
Edited 5/28/2005 7:18 pm ET by DAVERICHESON
I'd put in the drain (I used 6" dia perforated Hancor with a knit geotextile sock - DON'T use the "spunbound" sock - it looks like Tyvek, but doesn't allow groundwater to flow very well into pipe) and discharge it to a precast concrete dry well bedded and backfilled with crushed stone. A needlepunched, non-woven geotextile installed (first) outside the stone would help prevent migration of the sand thru the stone and into the drywell.
You didn't mention roof drainage; quite a bit a water runs off the roof. As others have said, much easier and less expensive to do now.
I opted for no perforated pipe on a foundation rebuild here. The contractor told me that I'd never get water into the pipe because the ground is so porous.
You should listen to your foundation contractor. Your own line of reasoning is missing one element: Murphy's Law.
As others have mentioned, it costs very little to do this now--and it is so expensive and invasive to do it later--that not doing it just doesn't make sense.
Dinosaur
A day may come when the courage of men fails,when we forsake our friends and break all bonds of fellowship...
But it is not this day.
Install the perforated 4" big O all around the perimeter footings and from there run non-perf to daylight... 4" big O is very inexpensive.
But digging a foundation up later to install drainage lines can be very expensive.
You say sanddy soil, not sand. Given your location in ( rpresumed since you didn't fill out your profile) New Hampshire, you still have humus and clay mixed with that sandy. That m,eans there can be pockets of water retaining soil on the property that can stopp crainage just where you don't want it to.
now, if you area NH Yank transplated into Florida sopils, maybe ou can do away with...but I wouldn't because the ability of the soil to perk water out as fast as a hurricane can dump it in is querstionable.
I have lived in only one plcae where we could do without drains. This was on a gravel benchj on the baks of the Colorado river. Deposits there left a clean gravel bed from 40 to 80 feet deep, and the annual rainfall/percipitation was about 15", mostly winter snow.
I've used the Formadrain footing syysten too, and liked it, but not every contractor does. It is more time consuming and expensive for the concrete sub, but effective overall. If the crete sub is not interested, it will not be worth using, because he will not be carefull enough with it ( never saw crette guys labeled "careful" ) to avoid breaking it.
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