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joshm 03-25-2008 10:01 AM

backfill ?
We have been water coming into our basement during heavy rains along one wall only. I think it maybe related to poor grading away from this wall as the ground is flat or slightly towards the house. Planning on trying backfill first. Here was my plan. I plan to put down heavy landscaping plastic or the like up the wall 6 inches and curve and run it out on the ground about 10 feet. I then plan to put about 12 inches of mostly clay backfill along the wall and slope this out over the 10 feet until it is level with the rest of the ground. Is 12 inches over 10 feet adequate? How about putting the plastic against the wall and under the dirt? I know I have read about people putting gravel over plastic but is it ok with dirt? I was thinking it would keep water from getting through to the basement wall and we would still be able to plant some small root flowers since there would be 8-12 inches of dirt near the house about the plastic. what do you think?

perpetual98 03-25-2008 10:07 AM

I would think that 12" over 10' would be more than enough, but I'm no expert. Just tagging along to see what other people are saying.

concretemasonry 03-25-2008 10:24 AM

Why don'y you dig down and put in drain tile surrounded by gravel. This will collect the water and carry it away to wherever you want.

joshm 03-25-2008 10:36 AM

dig down all the way to the footer or just a couple of feet below the ground level? Don't have the equipment, time, or money to dig up the whole thing especially if it is not necessary. I did consider putting a 4inch drain pipe about 16-24 inches below ground level though. Would that help?

concretemasonry 03-25-2008 12:30 PM

It is always easier and more reliable to get the water away instead of trying to waterproof a wall. Just because you have some clay does not mean it will stop water from seeping through. Clay must be the right type and compacted to be effective.

With a layer of clay or poly, there is always a way around it for the water to get down to accumulate at and leakage point.

you have to recognize that the backfill around a basement is never as impervious as the natural soil, no matter how much it is compacted.

When a hole is dug for a basement, you do not know whether it is for a house or a swimming pool - Does that tell you somehing. In addition, when a holes is dug, there is usually an access ramp down into it and some trenches for utilities. The soil is never compacted enough and the trenches go far beyond the 10 to 20 feet from the house.

I mention the drain pipe in case you can drain it away from the house. The depth is up to your time and ambition.

Wanttodoitright 03-25-2008 12:41 PM

I agree with these folks. Water will find a path around, or you could end up "ponding". With a rented trencher, the digging will be a snap and the drainage pipe, membrane, and gravel is cheap enough - compared to doing the job twice, once you notice water in the basement after the next heavy rain.

Once the drain is in, you can backfill and grade away from the house also. Your 24" deep drain will then be 30-36" deep, your grade will be better, and your basement will be dry. :thumbup:

Don't forget to call before you dig!

joshm 03-25-2008 01:42 PM

So you are not advocating that I dig all the way down to the foundation/footer? That is what some waterproofing companies wanted to do or they wanted to do it on the inside. I think the problem is being caused by rainwater and can be fixed if I diverted it away. 2 things have verified this for me. There is long run of wall then a covered porch and then another long run of wall. When when look in the basement along the same wall there is effloresence (sp?) along the first long run, nothing where the porch is, and then more along the next run. All of the water that actually seeps in comes in at a corner. Last time we had 2.5 inches of rain in a day I put tarps out and had them slanted away from the house and no water got it. So thats why I decided on backfill with plastic underneath. I have no problem running a perforated pipe even 1-2 feet deep and then backfilling over that but I am not going to dig up along the entire wall of my basement unless it I determine this doesn't work. So how about I dig down 2 feet into what I currently have say 16-24 inches away from my wall and lay gravel and drainpipe.Then place a solid sheet of plastic a few inches up the wall and over the area to be backfilled. Then backfill over this 12 inches at the wall sloping down to near ground level after the 10 feet. What do you think? Do this with or without the plastic? If I put the drain pipe in how far do I run it away from the house? Does it have to be sloped or can it be level? Is this what you were proposing or do you suggested digging down 8+ feet to the basement footer and installing a new drain pipe?

perpetual98 03-25-2008 01:54 PM

I think just reworking the slope of the soil is going to have a major impact and may be all you need.

jogr 03-25-2008 03:03 PM

I agree to starting with the very inexpensive step of correcting the slope with clay like you mentioned but without the plastic. The ground above the plastic would dry up faster in the summer and you'll never keep grass or plants alive. Make sure your gutters take the water 10' away from the house. Make sure your ground continues to slope away from the house even past the first 10'.

If you find that that doesn't work then I would proceed to the more expensive excavation to footing, proper drain tile & rock and proper waterproofing of the walls.

However, this cannot be done safely with a trencher as no one I know is crazy enough to go into an 8 foot deep trench even if it was wide enough to squeeze into. And is definitely not easy. Besides the mess of moving large quantities of dirt you will have to watch for and probably hand dig around every utility that runs into your house. And you will need to excavate a wide enough area to be braced safely to prevent dirt collapse.

Wanttodoitright 03-26-2008 02:00 AM

I was thinking more along the lines of a simple linear French drain system, which doesn't need to go down 8 feet. That's where you will only need a trencher. Worked like a charm behind my house.

joshm 03-26-2008 07:58 AM

wantto, thats what I was thinking about doing. How far away from the house do you instal it? How deep? and then where do you run it to? Does it have to open to daylight somewhere? Does it have to slope or can it be laid down fairly level?

Leah Frances 03-26-2008 09:15 AM

Check with your local building department. I need a permit to do backfilling/grading in my jurisdiction.

47_47 03-26-2008 10:45 AM

I would re-grade first. This should solve the problem. If you need to install a perforated pipe, I recommend either 4" perforated white pipe, or the 4" green. Use the green if you expect to drive over it with something heavy. Do not use the black flexible.
The pipe should run parallel to the house start at a depth of ~ 24", slope 1/4" per foot, the holes face down and cap the starting end. The closer to the house the better 2-3 feet is close enough. You will have to determine the point of discharge, where this water will not cause any other problems. The end of the pipe can be left above ground, but make sure that water will not lay in it and freeze, or it can end in a hole filled with stone (dry well).

Trenching is the hardest part and I would also consider running a second pipe (solid) to catch the downspout water.

call811beforeyoudig 04-23-2008 12:07 PM

Did you know that if you forget to get the underground utility lines marked before digging, it could cost you? For any project that requires digging, like creating a drainage system or installing a fence, call 811 before you start,or visit our website, for state specific info.

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