RE: French Drains . . . and other stuff

[firefighterjake]

A few questions . . .


My garage (poured slab with a 6-8 inch footer on top has water coming in after a heavy rain or in the Spring when the snow melts.

My plan is to dig down to the bottom of the exterior of the pad, repair any cracks and then apply some sort of water repellant (suggestions?).

I figure a French drain running along the perimeter may also help.

Question: How far out should the French drain be positioned?

Question: How far down should the French drain be located?

Right now my trench is approximately 1 1/2 feet wide from the pad out . . . and about 12 feet deep.

 

[Doc C]

A few questions . . .


My garage (poured slab with a 6-8 inch footer on top has water coming in after a heavy rain or in the Spring when the snow melts.

My plan is to dig down to the bottom of the exterior of the pad, repair any cracks and then apply some sort of water repellant (suggestions?).

I figure a French drain running along the perimeter may also help.

Question: How far out should the French drain be positioned?

Question: How far down should the French drain be located?

Right now my trench is approximately 1 1/2 feet wide from the pad out . . . and about 12 feet deep.

I don't understand why your trench would be 12 feet deep???

I've done many french drains over the years. Owned a landscaping business for several years and that was part of what we did.

1. Dig down carefully to expose the concrete. Preferably down to the footings. Consider hiring someone for this part mainly for the insurance coverage. If you do it yourself, stay back with the machine a foot or two and clean the walls up with a flat shovel.

2. Waterproof. Find whatever you can in bulk but make sure it's system that you use some sort of protective board over the top.

3. The most effective way to do a French drain is to place it about level with footing if ground water is the problem or about 1-2' down if surface water is the problem, if going to footings stay just barely above because by the time you slope it around the garage you don't want the drain to be below the footing and you want to leave the dirt the footing is sitting on undisturbed through the whole process. Make sure you hold a couple inches high all the way around.

4. Use black corrugated pipe with the fabric already on it. It needs to be placed on undisturbed soil that is preferably gently compacted, think hand tamper, not machines. I'm always extra careful around foundations and slabs. Slope your pipe minimum 1%. I like a little more if I have the room.

5. Find gravel. I like 3/4" to 1" with NO FINES. I can't stress that enough. Had to fix a drain someone else did because the fines were clogging the fabric around the pipe. Also had to fix another drain that they used schedule 40 with no holes?!?!?!?!

6. Backfill

7. Slope dirt away from garage all the way around.

8. Drink adult beverage of your choice and wait for a big rain snow to melt.

I just realized you said slab. Assuming 4" slab. Everything above applies. As long as you have room for your pipe to be underground without digging below the slab.

Others might say it's OK to dig below the slab or foundation but when my insurance is on the line I would rather be safe.

 

[firefighterjake]

Heh Heh . . . I meant to write 12 inches . . . about level with the pad.

Thanks for the response Doc . .. this was quite helpful.

 

[sportbikerider78]

I did a french drain around my property...quite extensive (1000+feet) and it is working quite well.

I used 4" pvc with holes pre-drilled. I used this because if there is a clog, you can send a snake up it w/o it destroying anything. You can't do that with the corrugated.

Dig your trench. Lay down some washed #2. Lay in your fabric (make sure it is geotextile, not some garbage landscape fabric). I used 3' wide.
More #2 stone.
Now wrap the stone and pipe up and top with at least 6" more stone.

Some top with top soil. I prefer to keep vegetation away to discourage roots from growing.

 

[Doc C]

In a properly designed French drain system with the right size rock and the rock ran out to the end of the pipe, the pipe will be the last resort for water to head out. You will see water flowing out the drain, in that 1-2" of rock you have the pipe sitting on, and then when the water level rises it will enter the pipe and flow out.

Most the drains I have had to fix over the years have been because the person that did the work used dirt and not rock to fill in the drain.

The one I had to fix with schedule 40 had no holes drilled in it. I dont see how drilling holes in the white pipe will be as adequate as using the heavy duty corrugated pipe made for French drains but with that said I don't know for sure as I have never repaired a system like that or installed one. Although it does seem like it could work and as stated above does seem to be working.

Also I'm not talking the cheap black corrugated pipe with the cheap fabric on it. That can work but it doesn't seem as reliable. Quite frankly on a drain that's only going to be 6-12" deep it would probably be fine if it's not driven on but there are better products out there.

Try googling NDS pipe. That's what I always try to use or something similiar. It is the black corrugated pipe with the fabric on it already. It's usually a white fabric and has some sort of poly like rock in it. The manufacturer claims that it can used without gravel.....I wouldn't do that. Knowing how a drain actually works in real life I treat the pipe as the last layer of protection for the water to flow through.

 

[johneh]

This the way we do it in Canada
But we call it weeping tile
(broken link removed to http://www.aquaguardinjection.com/basement-waterproofing-blog/weeping-tile-installation-the-fundamentals)
This tells you What ,wear,how and why

 

[firefighterjake]

Logged on this morning to ask a few questions . . . and one was already answered (whether to use gravel or rock around the pipe.)

I took some hydraulic cement and mortar that I had left over from past projects and patched up the seam/cracks where the footing meets the pad on one side of the garage yesterday evening . . . and started trenching the other side to see how the footing/pad looks.

There are a dizzying array of products to coat the concrete with . . . any personal recommendations?

Also, I'm seeing signs of efforescence . . . inside and outside. Is there any product I should use on the inside to help stop this?

Thanks again to everyone for the advice.

 

[sportbikerider78]

Also, I'm seeing signs of efforescence . . . inside and outside. Is there any product I should use on the inside to help stop this?

Thanks again to everyone for the advice.

I have no experience on your other questions, so I will not comment.

Efflorescence is due to hydrostatic pressure from the outside. You are going about this properly to prevent the pressure by getting rid of the water. With a good drain and good coating on the outside, you should be covered.

 

[sportbikerider78]

In a properly designed French drain system with the right size rock and the rock ran out to the end of the pipe, the pipe will be the last resort for water to head out. You will see water flowing out the drain, in that 1-2" of rock you have the pipe sitting on, and then when the water level rises it will enter the pipe and flow out.

Most the drains I have had to fix over the years have been because the person that did the work used dirt and not rock to fill in the drain.

The one I had to fix with schedule 40 had no holes drilled in it. I dont see how drilling holes in the white pipe will be as adequate as using the heavy duty corrugated pipe made for French drains but with that said I don't know for sure as I have never repaired a system like that or installed one. Although it does seem like it could work and as stated above does seem to be working.

Also I'm not talking the cheap black corrugated pipe with the cheap fabric on it. That can work but it doesn't seem as reliable. Quite frankly on a drain that's only going to be 6-12" deep it would probably be fine if it's not driven on but there are better products out there.

Try googling NDS pipe. That's what I always try to use or something similiar. It is the black corrugated pipe with the fabric on it already. It's usually a white fabric and has some sort of poly like rock in it. The manufacturer claims that it can used without gravel.....I wouldn't do that. Knowing how a drain actually works in real life I treat the pipe as the last layer of protection for the water to flow through.

There are certainly more than one way to skin this cat. No doubt about it.

I did not use schedule 40...which is quite expensive. I used this product from home depot. It was about $1/ft when I bought it. Schedule 40 is at least double to triple the price if you include fittings. These come with fittings.

The price varies from state to state by about 30%. Weird.
http://www.homedepot.com/p/4-in-x-10-ft-2-Hole-Triplewall-Pipe-4520010/100191022

 

[Doc C]

Logged on this morning to ask a few questions . . . and one was already answered (whether to use gravel or rock around the pipe.)

I took some hydraulic cement and mortar that I had left over from past projects and patched up the seam/cracks where the footing meets the pad on one side of the garage yesterday evening . . . and started trenching the other side to see how the footing/pad looks.

There are a dizzying array of products to coat the concrete with . . . any personal recommendations?

Also, I'm seeing signs of efforescence . . . inside and outside. Is there any product I should use on the inside to help stop this?

Thanks again to everyone for the advice.

I have always had waterproofing companies come out that have access to bulk water proofing systems and spray the concrete after I prepped in and then they would put a protective board depending on the system. Once that was done I would build a French drain.

I have used redguard on showers in my personal house with great success. My be worth doing some research and seeing if redguard is acceptable for outside use in this situation. Also drylock is another brand I have heard of people using with decent success but I thought that it was designed for interior use and that would not be the best way in your situation. But worth some research.

I wish I could be of more help but having not used any of the products designed for smaller projects in this application I am not sure what would be best.

 

[firefighterjake]

I have always had waterproofing companies come out that have access to bulk water proofing systems and spray the concrete after I prepped in and then they would put a protective board depending on the system. Once that was done I would build a French drain.

I have used redguard on showers in my personal house with great success. My be worth doing some research and seeing if redguard is acceptable for outside use in this situation. Also drylock is another brand I have heard of people using with decent success but I thought that it was designed for interior use and that would not be the best way in your situation. But worth some research.

I wish I could be of more help but having not used any of the products designed for smaller projects in this application I am not sure what would be best.

Trust me on this Doc . . . between you and Sportbike . . . you guys have helped me out immensely.

After checking out the various products I think I'll be going with a product from Lowes -- Black Jack rubber with fiber (#57) as it seems like the product will meet my needs as I am hoping to put it on the outside and inside of the garage footing as I find myself wondering if the snow/salt melt in the winter is affecting the concrete footings from the inside along with water penetration from the outside with rain and Spring snow melt.

I also checked out the NDS pipe . . . very cool stuff, but expensive. I figure I'll see what the price of buying a pre-sleeved corrugated pipe will cost me (along with the price of rock) and then get an idea of whether it would be worth doing the NDS pipe with the poly-rocks or go the conventional route.

 

[Doc C]

Trust me on this Doc . . . between you and Sportbike . . . you guys have helped me out immensely.

After checking out the various products I think I'll be going with a product from Lowes -- Black Jack rubber with fiber (#57) as it seems like the product will meet my needs as I am hoping to put it on the outside and inside of the garage footing as I find myself wondering if the snow/salt melt in the winter is affecting the concrete footings from the inside along with water penetration from the outside with rain and Spring snow melt.

I also checked out the NDS pipe . . . very cool stuff, but expensive. I figure I'll see what the price of buying a pre-sleeved corrugated pipe will cost me (along with the price of rock) and then get an idea of whether it would be worth doing the NDS pipe with the poly-rocks or go the conventional route.

I forgot about blackjack. My father in law is a roofer and uses that stuff on some flat roof repairs I think.

NDS pipe is going to more expensive for sure then the black pipe and bulk rock. Just keep in mind the the corrugated pipe you are talking about will do the job. It's just not really load bearing I don't think and it can be damaged pretty easy. Just keep that in mind during and after your install and you will probably be fine. I have never had a drain clog although I have heard of several but like sport bike brought up it may be damaged if you ever have to clean it out.

Good luck!

 

[Doc C]

Trust me on this Doc . . . between you and Sportbike . . . you guys have helped me out immensely.

After checking out the various products I think I'll be going with a product from Lowes -- Black Jack rubber with fiber (#57) as it seems like the product will meet my needs as I am hoping to put it on the outside and inside of the garage footing as I find myself wondering if the snow/salt melt in the winter is affecting the concrete footings from the inside along with water penetration from the outside with rain and Spring snow melt.

I also checked out the NDS pipe . . . very cool stuff, but expensive. I figure I'll see what the price of buying a pre-sleeved corrugated pipe will cost me (along with the price of rock) and then get an idea of whether it would be worth doing the NDS pipe with the poly-rocks or go the conventional route.

Oh and please if you do decide to go with the NDS still use rock. I may be wrong but I don't think the poly rock should take the place of no rock at all. It doesn't seem right and I think you will be better off with rock as well. And as cheap as rock is by the yard of you have a truck it's not worth doing it without.

I can buy washed 3/4"-1" rock for about $28 a yard in my area.

 

[firefighterjake]

I forgot about blackjack. My father in law is a roofer and uses that stuff on some flat roof repairs I think.

NDS pipe is going to more expensive for sure then the black pipe and bulk rock. Just keep in mind the the corrugated pipe you are talking about will do the job. It's just not really load bearing I don't think and it can be damaged pretty easy. Just keep that in mind during and after your install and you will probably be fine. I have never had a drain clog although I have heard of several but like sport bike brought up it may be damaged if you ever have to clean it out.

Good luck!

I'm planning on laying the trench/pipe to the sides of the garage and house where it should receive little to no traffic . . . other than foot traffic and maybe my ATV as I plow the side when the snow flies.

 

[Doc C]

I'm planning on laying the trench/pipe to the sides of the garage and house where it should receive little to no traffic . . . other than foot traffic and maybe my ATV as I plow the side when the snow flies.

How do you like plowing with an ATV? My driveway is about 1/4 mile long, flat, straight, but I have one area that gets drifts up to about 3' if I don't keep up on it.

I live in Northern Idaho and I'm guessing that's comparable to Maine snow wise. Lots of snow! Average storms are probably 4"-18" at a time.

I am picking up a 2017 Polaris 570 next week and was thinking a plow might be a good idea. I have been using an old chevy truck with a plow but I need to dump aboit $5000 into it to make it reliable and I don't know if it's worth it.

 

[semipro]

I'd add to what's been shared by suggesting strongly that you always separate gravel from soil with filter fabric, whether the soil lies above or below the gravel. Its cheap insurance. Any time your soil is in contact with the gravel there's the potential for the the soil to fill the pore spaces causing clogging and subsidence. I also 2nd the suggestion to use the smooth interior PVC rather than corrugated.

Also, gutters downspouts should not connect with french drains if possible.
And, an water impervious material (like roofing underlayment) can be buried next to, and sloped away from, the slab to further clear water away from the structure, though this is typically done adjacent to basements.

 

[Doc C]

I'd add to what's been shared by suggesting strongly that you always separate gravel from soil with filter fabric, whether the soil lies above or below the gravel. Its cheap insurance. Any time your soil is in contact with the gravel there's the potential for the the soil to fill the pore spaces causing clogging and subsidence. I also 2nd the suggestion to use the smooth interior PVC rather than corrugated.

Also, gutters downspouts should not connect with french drains if possible.
And, any water impervious material (like roofing underlayment) can be buried next to, and sloped away from, the slab to further clear water away from the structure, though this is typically done adjacent to basements.

That's actually a good point about the gutters. If they can't be run easily to a slope that heads away from the garage then I have built dry wells in the past. Simply dig a decent size hole usually 4-5' around and down far enough to get past the frost line, fill with the same rock you use for your drain, run gutter downs spout to it and call it good. Preferably several feet away from your French drain. And you HAVE to go below the frost line.

But if you are like us and your garage roof is metal then we do not use gutters because we would have to replace them after every winter.

 

[Dobish]

Funny, I was just about to start digging a french drain for our cottage. The other day it poured for about 2 hour straight, and i happened to notice water coming through the floor. We just had tenants move out, and we were in there cleaning, which is the only reason I noticed (i don't go in there often). The last time this happened, it was because the gutter was disconnected, so I went outside to look. Gutter was connected, but the rain was so heavy that it wasn't even going into the gutter! The rain was pooling up outside and seeping through the concrete blocks!

I have been waiting to finish up a few projects, but I was going to dig a trench and lay down a french drain (we also have another gutter that sort of runs into that area as well, so I was just going to bury them both together). I have had good luck with french drains, especially here where the water hits the ground and starts running before the ground softens, and we get large pools.

I have another spot on the front of my house that I needed to come up with a creative solution, since the gutter downspout went into concrete, then would pour right down the side of the house, then into the basement. That was super fun! I finally ended up connecting a number of pieces under the deck, and then doing a french drain away from the house.

 

[firefighterjake]

How do you like plowing with an ATV? My driveway is about 1/4 mile long, flat, straight, but I have one area that gets drifts up to about 3' if I don't keep up on it.

I live in Northern Idaho and I'm guessing that's comparable to Maine snow wise. Lots of snow! Average storms are probably 4"-18" at a time.

I am picking up a 2017 Polaris 570 next week and was thinking a plow might be a good idea. I have been using an old chevy truck with a plow but I need to dump aboit $5000 into it to make it reliable and I don't know if it's worth it.

It's good and bad . . . keeps my ATV moving in the winter instead of just sitting there and the plow set up is pretty reasonable.

The negative is you're exposed to the cold . . . it takes longer to do vs. plowing with a truck and you learn early on to push your snow banks way, way back since once the snow firms up those banks are there until Spring -- there's no moving them back later on.

I took a look at the Polaris 570 SP before buying a Yamaha Kodiak 700 EPS two weeks ago . . . they ride nicely and are nicely equipped.

 

[firefighterjake]

That's actually a good point about the gutters. If they can't be run easily to a slope that heads away from the garage then I have built dry wells in the past. Simply dig a decent size hole usually 4-5' around and down far enough to get past the frost line, fill with the same rock you use for your drain, run gutter downs spout to it and call it good. Preferably several feet away from your French drain. And you HAVE to go below the frost line.

But if you are like us and your garage roof is metal then we do not use gutters because we would have to replace them after every winter.

Yup . . . no gutters on the house or garage . . . for that exact reason.

The Scene: Snow falling gently in the late afternoon or early evening in winter. The fire is crackling. The TV is on low. The cats have staked out their favorite sleeping spots.

WHOOOOOOOOOOOOOOOOOOOOOOOO-SSSSSSSSSSSSSSSSSSSSSSHHHHHHHHH!!

THUMMMMMMMMMPPPPPPPPPPPPPP . . . THUMMMMPPPPPPPPP . . . THUMMMMMPPPPPPP!

Cats scatter.

 

[Buzz Saw]

Interesting read. Here in Ohio we tile our farm fields with corrugated tile. Never have we ever put stone/rocks down with the tile. The tile guys used to use big trenches but now they use tile plows. The only time we ever get dirt in the tile is if there is a hole in the tile(typically from a woodchuck). I recently dug up a 50 year old corrugated tile and it had very little dirt in it. I understand this is for around a building footer, but I thought I would comment that dirt doesn't get into tiles that fast or extensively.

The only time we use limestone is around footers and foundations. Tile at the footer then back fill with 57's and then 18" or so of dirt o n top.

There is also a smooth interior wall corrugated tile sold in 20' sticks that is rated for heavy loads. We usually use it for driveway crossings.

I suppose what and how you do things is all dependant on soil type as well.



Sent from my SM-G950U using Tapatalk

 

[sportbikerider78]

Trust me on this Doc . . . between you and Sportbike . . . you guys have helped me out immensely.

After checking out the various products I think I'll be going with a product from Lowes -- Black Jack rubber with fiber (#57) as it seems like the product will meet my needs as I am hoping to put it on the outside and inside of the garage footing as I find myself wondering if the snow/salt melt in the winter is affecting the concrete footings from the inside along with water penetration from the outside with rain and Spring snow melt.

I also checked out the NDS pipe . . . very cool stuff, but expensive. I figure I'll see what the price of buying a pre-sleeved corrugated pipe will cost me (along with the price of rock) and then get an idea of whether it would be worth doing the NDS pipe with the poly-rocks or go the conventional route.

Post pics or it didn't happen!

That way we can armchair quarterback you and feel a sense of superiority!

 

[firefighterjake]

Post pics or it didn't happen!

That way we can armchair quarterback you and feel a sense of superiority!

This is probably a good idea.

I've dug out the pad and footings around the garage on the two sides where the snow slides off the roof and patched a couple of cracks and gaps with concrete -- mostly where the pad and footing come together (it almost looks like the footing's concrete wasn't as good a mix). I also repaired the badly spalled concrete footing inside the garage.

I've dug some trenches . . . going down to the base of the pad (not sure if I should actually dig down a bit further . . . I'm also unsure if I should have dug the trench so close to the pad -- I did so as I wanted to expose the pad and coat it with a damp-proof asphalt covering (something not done in my 1970s era built home and garage). Digging has been pretty easy since it's been a coarse gravel around the foundation with some sand as I went further out from the garage.

Project for today or tomorrow is to apply the outside coating on the foundation . . . possibly a coating on the inside footing with Drylok paint. I've also got a load of stone coming this evening -- 6 yards of small stone (one inch or so).

Based on everyone's recommendations and realization that working with the coiled up corrugated drainage pipe could a) be a pain to work with and b) would not be as crush-proof I bought the triple wall drainage, smooth drainage pipe. Figured it will cost me a bit more, but may work better in the long run. I did buy a reducer/adapter to switch to Schedule 40 3 inch pipe as one of my planned configurations will have me using the perforated pipe for 18 or so feet, taking a 45 degree angle and going out another 5 or so feet and then switching to the Schedule 40 for another 20-25 feet. I opted to do this as this spot is where I back up my truck loaded with firewood and figure the Schedule 40 might hold up better to the weight vs. the triple wall drainage.

After doing my "painting" and a little more interior concrete work (just a couple of spots) I'm hoping to lay out my pipe to make sure I have everything I need and check the angle of the dangle . . . then it will be time to glue it together and start shoveling stone.

 

[sportbikerider78]

Don't obsess over crushing the pipe. It's all about weight distribution. Keep some 3/4" plywood handy to distribute weight if you must do it.

 

[Doc C]

This is probably a good idea.

I've dug out the pad and footings around the garage on the two sides where the snow slides off the roof and patched a couple of cracks and gaps with concrete -- mostly where the pad and footing come together (it almost looks like the footing's concrete wasn't as good a mix). I also repaired the badly spalled concrete footing inside the garage.

I've dug some trenches . . . going down to the base of the pad (not sure if I should actually dig down a bit further . . . I'm also unsure if I should have dug the trench so close to the pad -- I did so as I wanted to expose the pad and coat it with a damp-proof asphalt covering (something not done in my 1970s era built home and garage). Digging has been pretty easy since it's been a coarse gravel around the foundation with some sand as I went further out from the garage.

Project for today or tomorrow is to apply the outside coating on the foundation . . . possibly a coating on the inside footing with Drylok paint. I've also got a load of stone coming this evening -- 6 yards of small stone (one inch or so).

Based on everyone's recommendations and realization that working with the coiled up corrugated drainage pipe could a) be a pain to work with and b) would not be as crush-proof I bought the triple wall drainage, smooth drainage pipe. Figured it will cost me a bit more, but may work better in the long run. I did buy a reducer/adapter to switch to Schedule 40 3 inch pipe as one of my planned configurations will have me using the perforated pipe for 18 or so feet, taking a 45 degree angle and going out another 5 or so feet and then switching to the Schedule 40 for another 20-25 feet. I opted to do this as this spot is where I back up my truck loaded with firewood and figure the Schedule 40 might hold up better to the weight vs. the triple wall drainage.

After doing my "painting" and a little more interior concrete work (just a couple of spots) I'm hoping to lay out my pipe to make sure I have everything I need and check the angle of the dangle . . . then it will be time to glue it together and start shoveling stone.

Also don't stress about digging the dirt near the foundation to expose it. It has to be done and the dirt does not add any strength to the side of the concrete. Unless of course you have some sort of extremely inferior crumbly concrete but then you have even bigger problems. All your strength is pushing straight down.

Also personally I do not disturb the ground below footings. Doesn't seem like a good idea. I have on rareoccasion dug a small like 6" or less trench under footing to run a pipe or conduit or something but that's rare and a last resort.

The guidelines for pouring footings in our area is either to be on undisturbed soil or compact the soil to a certain psi.