Underlayment / Overlayment?

[ATP]

I have been trying to research what is the best source for purchasing the pond liner underlayment for an EPDM liner and it seems people use all different types of materials. I just re-did flooring in my house and have a bunch of used carpet. I am hesitant to use it because of thickness and possible staples throughout. I am fine with purchasing underlayment but not sure the most cost effective route. Can I simply buy weed fabric from the big box stores or should I get something more specialized? I know I could just buy underlayment sold by one of the online pond supply shops, however, I am guessing the prices are inflated for what it really is.

Also for an overlayment, can i use the same material as the underlayment? I am planning on lining the bottom with small round stone. For the vertical sections I will be attempting to get the largest boulders I can find that I will still be able to physically manuever without the need for machinery. Should I plan on overlaying the liner completely or just under the large boulders?

 

[brokensword]

I have been trying to research what is the best source for purchasing the pond liner underlayment for an EPDM liner and it seems people use all different types of materials. I just re-did flooring in my house and have a bunch of used carpet. I am hesitant to use it because of thickness and possible staples throughout. I am fine with purchasing underlayment but not sure the most cost effective route. Can I simply buy weed fabric from the big box stores or should I get something more specialized? I know I could just buy underlayment sold by one of the online pond supply shops, however, I am guessing the prices are inflated for what it really is.

Also for an overlayment, can i use the same material as the underlayment? I am planning on lining the bottom with small round stone. For the vertical sections I will be attempting to get the largest boulders I can find that I will still be able to physically manuever without the need for machinery. Should I plan on overlaying the liner completely or just under the large boulders?

I've used old carpet remnants for v1 but didn't like when I had to tweak when some embankment started to slide behind; created a bulge and the carpet was a pita to manipulate. Others have done so with success. Some use newspapers. Some use thin, large sheets of foam from a foam surplus store. When I did v2, I found I didn't need ANY underlayment with HDRPE liner, so didn't bother. The HDRPE is also lighter and cheaper, if that is of interest to you.

I'd think you could use weed barrier, though it's thinner. Some protection by using underlayment is for any sharp protrusions that might occur over time. If your hole is not in that jeopardy, should be okay to use thinner underlayment. You could also put some sand down first, on the bottom, and that would help.

If rocking inside the pond, good idea to put underlayment under every large boulder; keeps the liner from eventually stretching and ripping there. I don't think you need anything under smallish boulders.

 

[Dimelius]

I bought my underlayment from a building store, non-woven fabric for covering...cheaper then pond shops and exatcly the same, just buy high grams...or like i did, i made 2 layers...and anyway gone cheaper, then on shelfs and bottom i used sands+old work shirts/pants...

About boulders, like brokensword said, only on BIG boulders..if others are small...but depends on what you mean with small

 

[combatwombat]

What’s your soil like? Nice and loamy or sharp rock everywhere? Really depends on local conditions what you can get away with.

Also for an overlayment, can i use the same material as the underlayment?

Depends on what you use for underlayment! Would use carpet inside the pond!

 

[Jhn]

Used 8oz nonwoven filter fabric, the stuff is incredibly tough, even hard to cut with a knife. Used it under and over the entire pond liner, but my pond has large rocks in it. I would use underlay over all of the pond liner if you are rocking it as well, when I had to find a leak the spot was under a smaller rock.

 

[j.w]

Anything soft and not pokey can be used from blankets, cardboard, towels, carpet, rugs, the list goes on! I have used them all. We have sandy soil w/o hardly any rocks but I still wanted to be safer. I don't have rocks on the bottom of my pond, only around the top edge and on a short ledge down about 8" or so to hide the liner when filled w/water.

 

[ATP]

I bought my underlayment from a building store, non-woven fabric for covering...cheaper then pond shops and exatcly the same, just buy high grams...or like i did, i made 2 layers...and anyway gone cheaper, then on shelfs and bottom i used sands+old work shirts/pants...

About boulders, like brokensword said, only on BIG boulders..if others are small...but depends on what you mean with small

Basically biggest I can muscle around the yard into the pond. Still need to visit the local quarryies to see what I can find. Hopefully, at least around 16" in diameter.

 

[ATP]

What’s your soil like? Nice and loamy or sharp rock everywhere? Really depends on local conditions what you can get away with.


Depends on what you use for underlayment! Would use carpet inside the pond!

Soil should be a mix. Its mostly likely going to go in my front yard and since that is also where the septic is, the builder didnt do a very good job of adding top soil. I had to have some septic work done and it was easy digging and sandy. If I put it in the back it will be sandy on top, some rocks and more of clay mix in the back.

You would use carpet inside?

 

[Jhn]

Soil should be a mix. Its mostly likely going to go in my front yard and since that is also where the septic is, the builder didnt do a very good job of adding top soil. I had to have some septic work done and it was easy digging and sandy. If I put it in the back it will be sandy on top, some rocks and more of clay mix in the back.

You would use carpet inside?

No would not use carpet in the pond, it will fall apart, use non woven filter fabric, the stuff isn’t that expensive.

 

[combatwombat]

Sorry, I meant “would not” use carpet in the pond. Too late to edit post.

 

[GBBUDD]

Can I simply buy weed fabric

Fabric is area specific, if you were in the deep south and the red clay or along the coast and nothing but sand then a thinner fabric can be used, ifm you used any at all . Regardless of the thickness i would use "{ Non woven Needle punched polypropylene fabric }' it will last for decades below grade. Now certain parts of NY has lots of granite while others have sand , sandy clay or even slate and shale. it all depends what you have as to the thickness. As @Jhn stated i like the 8 oz as well very durable and tough stuff { GOT MINE AT lOWES SPECIAL ORDER.} but if your on shale it may not be even tough enough. A layer of sand like two or three inches to start or a higher oz content non woven can get very thick. As also mentioned above i would spend the money i'm not a fan of old carpet or cloth. I guess it mainly depends are you building a weekender project or are you building a three month or more. The risks would determine how far I took the precautions or some insurance. i ALSO AGREE WITH @Jhn AS TO INSIDE THE POND AND COVERING IT ALL even nice smooth river rock or peastone can spit and always have some that is and when that happens it can be like a razors edge. @Jhn and i have similar ponds where we have a lot of time and money invested so the insurance of a few hundred dollars to insure the pond lasted for decades was worth the investment.

 

[GBBUDD]

Soil should be a mix. Its mostly likely going to go in my front yard and since that is also where the septic is, the builder didnt do a very good job of adding top soil. I had to have some septic work done and it was easy digging and sandy. If I put it in the back it will be sandy on top, some rocks and more of clay mix in the back.

You would use carpet inside?

pLACING YOUR POND IN THE SAND OF YOUR SEPTIC OR LEACHING FIELDS IS NOT ADVISED. Your taking away the volume of area needed for them to work properly

 

[Lisak1]

While I know many use all kinds of things for underlayment, by my way of thinking the first things that go IN the pond are the last things that would come OUT. So if anything were to go wrong with underlayment or liner, I'd be stuck taking out everything else to do-over. I would never recommend trying to save money on those two things when building a pond, especially since both are relatively inexpensive all things considered.

 

[ATP]

Fabric is area specific, if you were in the deep south and the red clay or along the coast and nothing but sand then a thinner fabric can be used, ifm you used any at all . Regardless of the thickness i would use "{ Non woven Needle punched polypropylene fabric }' it will last for decades below grade. Now certain parts of NY has lots of granite while others have sand , sandy clay or even slate and shale. it all depends what you have as to the thickness. As @Jhn stated i like the 8 oz as well very durable and tough stuff { GOT MINE AT lOWES SPECIAL ORDER.} but if your on shale it may not be even tough enough. A layer of sand like two or three inches to start or a higher oz content non woven can get very thick. As also mentioned above i would spend the money i'm not a fan of old carpet or cloth. I guess it mainly depends are you building a weekender project or are you building a three month or more. The risks would determine how far I took the precautions or some insurance. i ALSO AGREE WITH @Jhn AS TO INSIDE THE POND AND COVERING IT ALL even nice smooth river rock or peastone can spit and always have some that is and when that happens it can be like a razors edge. @Jhn and i have similar ponds where we have a lot of time and money invested so the insurance of a few hundred dollars to insure the pond lasted for decades was worth the investment.

Thanks GBBUDD. What you have described is what I am planning on getting. What width did you go with? looks like it may come in 3' and 6'. Did you you the same underlayment as an overlayment throughout your entire pond or did you just place it under the big boulders.

I have a mix of granite, some shale, sand, even bedrock I believe. When our pool was installed they needed to blast to get it down to depth in the deep end. So there is no telling what i will find.

Amazing pond btw...I have spent some time on your build thread!

 

[ATP]

pLACING YOUR POND IN THE SAND OF YOUR SEPTIC OR LEACHING FIELDS IS NOT ADVISED. Your taking away the volume of area needed for them to work properly

Where i am thinking about putting the pond it wont be near the leach field or septic. As of now th pond will be going right off the walkway to our front door. the septic and leach field will be further out in the yard.