Forums | Home Repair | Home Improvement | Painting | Interior Decorating | Remodeling | Landscaping


Go Back   DIY Chatroom Home Improvement Forum > Home Improvement > Landscaping & Lawn Care

CLICK HERE AND JOIN OUR COMMUNITY TODAY...IT'S FREE!

Reply
 
Thread Tools Search this Thread Display Modes
Old 09-17-2011, 03:22 PM   #1
Member
 
Join Date: Feb 2011
Posts: 39
Share |
Default

Drainage / French Drain Questions


Hello,

I recently had a new concrete patio poured and the water is draining away from my house which is good. But I'm worried that the water will pool up on the dirt right off of the patio. I was thinking of installing a French Drain running parallel with my patio and another running parallel with my driveway to collect water. Then connecting those french drains into a drainage box with surface drain then from the drainage box it would connect to the 4 inch non-perforated PVC pipe that is running under the patio which would take it out to the street.

After doing some more reading I'm not sure that this will work since french drains normally collect water from underneath them not water falling on top of them. Is that correct?

If anyone has any ideas on how I can catch the runoff from the patio and get it to my non-perforated pipe that is underneath the patio please let me know. I would appreciate any help I could get.

I have attached two pictures of the patio / driveway and marked where the french drains would be installed.

Thanks
Attached Thumbnails
Drainage / French Drain Questions-photo-2.jpg   Drainage / French Drain Questions-photo-1.jpg  
bsmith95610 is offline   Reply With Quote
Old 09-17-2011, 05:24 PM   #2
Member
 
concretemasonry's Avatar
 
Join Date: Oct 2006
Location: Minneapolis/St. Paul, Minnesota - Latitude 45.057 Longitude -93.074
Posts: 3,641
Default

Drainage / French Drain Questions


French drains collect water from around them or just from the top. If you use pipe for collection, use perforated PVC with the holes at 4:00 and 8:00 have at least 4" of well drained fill under and around the pipe. You can use a "sock" around the pipe, which is the easy way, but installations that have lasted for decades used a properly grades mixture of clean granular materials definitely just "rock" which can promote clogging and reduce the collection ability. Landscaping fabric (not available decades ago) between the natural soil new graded granular soil around the pipe is always a plus.

Dick
concretemasonry is online now   Reply With Quote
Old 09-17-2011, 06:52 PM   #3
Member
 
Join Date: Nov 2007
Location: Nashua, NH, USA
Posts: 6,781
Default

Drainage / French Drain Questions


A French drain can also be on the surface as a hard surfaced channel or ditch(no pipe) that carries the water away (by gravity) before much can soak into the immediate ground.

This can also tie into dry wells or sumps or underground French drains.

For an underground French drain, a perforated pipe will collect only the water even with it or above it. Some water will flow through the gravel under the perforated pipe to get to the sump (pit). Most of the water below the layer of gravel in the trench will stay behind.

So an underground French drain outside used to collect rain water around the house but which is above foundation footing level will not collect water already down at foundation footing level.
__________________
The average homeowner who lost his house in the Oklahoma tornadoes should move for good and not rebuild. Too much complexity watchdogging the contractor. Too much a chance to be defrauded.

Last edited by AllanJ; 09-17-2011 at 07:05 PM.
AllanJ is offline   Reply With Quote
Old 09-17-2011, 09:01 PM   #4
Member
 
concretemasonry's Avatar
 
Join Date: Oct 2006
Location: Minneapolis/St. Paul, Minnesota - Latitude 45.057 Longitude -93.074
Posts: 3,641
Default

Drainage / French Drain Questions


The depth of the pipe is precisely why the "french" drain around the home is placed with the bottom of the footing so it prevents excess water against the wall and reduces the pressure that can cause leakage. On the interior, it cuts off the water flow from ouside the footing perimeter and reduces the hydrostaic pressure under the slab that can cause leaks or crack, depending on the soil. The level of the bottom of the pipe or gravel controls the bottom level of where they are effective.

French drains do not drain water away quickly like a curb or formed drain, they do increase the amount of moisture in the soil that allows the soil to take onextra water for storage before draining more actively. Some french drains may not drain water into a sump or to daylight immediately after a storm, but only when the soil at that level becomes saturated.

The open "french" drains with or without a perforated pipe have been used for decades on golf courses to minimize the wet areas since they are hidden and buried in a trench that does not alter the contours of the golf course. The course I played on from 1970 to 1990 had active subsurface drainage that was installed before, but still worked well even without perforated pipes. "If it ain't broken, don't try to fix it".

There are many thousands of acres of fields in Iowa that are drained for agriculture using loosely jointed clay and concrete pipe ever row of three. This allows earlier planting and a longer growing season.

French drains are everywhere, but you never see them.

Dick
concretemasonry is online now   Reply With Quote
Old 09-18-2011, 01:17 AM   #5
Member
 
Join Date: Feb 2011
Posts: 39
Default

Drainage / French Drain Questions


So when I install the french drain should I dig it down so the pipe is a few inches below the bottom of the concrete patio and one foot or so to the side of the patio?
bsmith95610 is offline   Reply With Quote
Old 09-18-2011, 08:05 AM   #6
Member
 
Join Date: Nov 2007
Location: Nashua, NH, USA
Posts: 6,781
Default

Drainage / French Drain Questions


By the way, the surface French drain is named after the country. The underground French drain is named after someone.

For draining water running off the patio/driveway only, an underground French drain need only be a few inches below the surface but can freeze up in winter. The desirability of a surface French drain also depends on how good it looks after figuring in the needed slope.

To avoid undermining and possible cracking of the slab, it's a choice of whether to dig the trench almost against the patio/driveway at a depth equal to the patio/driveway slab bottom, or a foot away and a few inches lower.
__________________
The average homeowner who lost his house in the Oklahoma tornadoes should move for good and not rebuild. Too much complexity watchdogging the contractor. Too much a chance to be defrauded.

Last edited by AllanJ; 09-19-2011 at 09:17 PM.
AllanJ is offline   Reply With Quote
The Following User Says Thank You to AllanJ For This Useful Post:
concretemasonry (09-18-2011)
Old 09-18-2011, 09:00 PM   #7
Member
 
Join Date: Jan 2007
Posts: 1,770
Default

Drainage / French Drain Questions


I think what you're referring to are "catch basins," not "french drains."
handy man88 is offline   Reply With Quote
Old 09-18-2011, 10:00 PM   #8
Member
 
Join Date: Nov 2007
Location: Nashua, NH, USA
Posts: 6,781
Default

Drainage / French Drain Questions


A catch basin is an underground tank or vault with a surface inlet where water flowing from elsewhere (perhaps via a French drain) is dumped in. It must have some outlet down below (perhaps to a storm sewer) or be equipped with a sump pump.

A "French drain" that is supposed to be the end destination of the water which soaks into the surrounding soil is a leach field.
__________________
The average homeowner who lost his house in the Oklahoma tornadoes should move for good and not rebuild. Too much complexity watchdogging the contractor. Too much a chance to be defrauded.
AllanJ is offline   Reply With Quote
Old 09-19-2011, 03:55 PM   #9
Member
 
Join Date: Jan 2007
Posts: 1,770
Default

Drainage / French Drain Questions


Quote:
Originally Posted by bsmith95610 View Post
Hello,

I recently had a new concrete patio poured and the water is draining away from my house which is good. But I'm worried that the water will pool up on the dirt right off of the patio. I was thinking of installing a French Drain running parallel with my patio and another running parallel with my driveway to collect water. Then connecting those french drains into a drainage box with surface drain then from the drainage box it would connect to the 4 inch non-perforated PVC pipe that is running under the patio which would take it out to the street.

After doing some more reading I'm not sure that this will work since french drains normally collect water from underneath them not water falling on top of them. Is that correct?

If anyone has any ideas on how I can catch the runoff from the patio and get it to my non-perforated pipe that is underneath the patio please let me know. I would appreciate any help I could get.

I have attached two pictures of the patio / driveway and marked where the french drains would be installed.

Thanks
You can "catch the runoff from the patio" via catch basins and connect to your non-perforated pipe that is already underneath your patio.

Hopefully, this pipe outlets into the street so that it doesn't need to be pumped.
handy man88 is offline   Reply With Quote
Old 09-19-2011, 09:53 PM   #10
Member
 
Join Date: Feb 2011
Posts: 39
Default

Drainage / French Drain Questions


So would it be better to use two or three catch basins instead of a french drain? I was going to install one catch basin in the corner then do two french drains as well. But if it is better to do multiple catch basins I will try that instead.

Wouldn't a lot of water get missed with the catch basins since in between two catch basins there could be a lot of water coming into the yard? I imagine the water will come down pretty much evenly across the patio.

Thanks
bsmith95610 is offline   Reply With Quote
Old 09-20-2011, 04:07 PM   #11
Member
 
Join Date: Jan 2007
Posts: 1,770
Default

Drainage / French Drain Questions


Quote:
Originally Posted by bsmith95610 View Post
So would it be better to use two or three catch basins instead of a french drain? I was going to install one catch basin in the corner then do two french drains as well. But if it is better to do multiple catch basins I will try that instead.

Wouldn't a lot of water get missed with the catch basins since in between two catch basins there could be a lot of water coming into the yard? I imagine the water will come down pretty much evenly across the patio.

Thanks
I would recommend using catch basins and do whatever you can do to get the grading to drain towards the catch basins.

If water is flowing at a fast rate, I seriously doubt if french drains (trench filled with gravel, then with perforated pipe, and then with more gravel) will allow water to drain fast enough.

For long narrow lengths, you should consider storm drain/trench channels:

http://www.google.com/imgres?q=drain...:0&tx=96&ty=86

http://www.google.com/imgres?q=drain...25&tx=98&ty=91
handy man88 is offline   Reply With Quote
Old 09-20-2011, 07:03 PM   #12
Engineering Technologist
 
Join Date: Sep 2011
Location: ohio
Posts: 18
Default

Drainage / French Drain Questions


If those circles are representing inlet basins, I don't think they will catch much water if I'm seeing the pictures right. You could just tie your pipe straight into the pipe going under the patio. The depth of the french drain pipe can only be as deep as the pipe going under the patio. The pipe should have a layer of stone under it then position the holes down. Otherwise the pipe will collect silt and plug up. Then envelope the entire pipe with stone. Ideally , you can put a sock over the pipe and wrap the stone and pipe in fabric. The stone should be what is called "poorly graded" stone. Meaning the stone is close to the same size with no fines. Number 57 size stone is a good size. The only problem with this is you will be constantly maintaining the surface so that silt, leaves and such won't be resting over the trench blocking the drainage.
runoff is offline   Reply With Quote
Old 09-21-2011, 10:40 AM   #13
Member
 
Join Date: Feb 2011
Posts: 39
Default

Drainage / French Drain Questions


If I try to use the storm drain/trench channels can I install those at the end of the concrete where the grass will start? I don't want to have to pour more concrete or chip away existing concrete to fit a drain/trench channel.
bsmith95610 is offline   Reply With Quote
Old 09-21-2011, 10:45 AM   #14
Engineering Technologist
 
Join Date: Sep 2011
Location: ohio
Posts: 18
Default

Drainage / French Drain Questions


No, just install them in the ground right against the concrete at ground level.
runoff is offline   Reply With Quote
Old 09-21-2011, 11:27 AM   #15
Member
 
Join Date: Feb 2011
Posts: 39
Default

Drainage / French Drain Questions


Runoff - So are you saying I can use any product similar to the one listed below and just install it right up against the concrete then put in either at the same level or an inch below the level of the concrete?

So will the trench drain eventually shift down since it will actually be sitting in the soil? If so should I dig the ditch tamp the bottom of it then put an inch or two of rock below it so it doesn't shift as much?

I appreciate the input.

http://www.google.com/products/catal...ed=0CHsQ8wIwAw
bsmith95610 is offline   Reply With Quote
Reply

Tags
drainage, french drain, patio


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Drain tile questions for retaining wall installation. Tmaxx1 Landscaping & Lawn Care 11 06-10-2011 11:17 AM
Installing french drain / weeping tile Troglodyte Landscaping & Lawn Care 0 05-12-2011 08:33 PM
Central Air Secondary Drain Leaking - 3 questions walters_12 HVAC 7 05-11-2011 03:20 PM
French drain to no sidewalk? phake123 Building & Construction 7 05-16-2010 06:03 AM
French Drain Suggestions doublejz Landscaping & Lawn Care 10 04-29-2010 03:19 PM




Top of Page | View New Posts

Copyright © 2003-2014 Escalate Media. All Rights Reserved.