Replacing Liner, Foam Board****Now Done w/Pictures

rob.mwpropane

In The Industry
Jun 9, 2015
201
Baldwin, Maryland
*************** I have finished this project and added pictures through a dropbox link on the second page ***************************


Good day, I have to replace my liner. The sand under the liner hasn't been the best and I've read here and there about the foam board. I understand it should be taped, but I'd like to know what thickness the board should be, and if possible where's the cheapest place to get it? If I go to home depot it looks like it would be about ~ $250. If it's 4x8 sheets I think I'm looking at getting ~ 17 for a 16x32 pool.

Thoughts? Experience? Thanks!
 
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Spiderfish

New member
Jul 5, 2015
2
Regina, SK
I used 1" extruded insulation, taped the seams with sheathing tape, and then covered it with a layer of 60 mil EPDM roofing membrane (similar to pond liner material) under my Intex 12x24 Ultraframe. The membrane was likely unnecessary, however being in the roofing industry, I had it laying around so I used it. I've had the pool up for 5 years now, left it up through the cold northern winters, and the bottom is as smooth and flat as the day I installed it.

One thing to mention about "foam board", there are a few different types of rigid insulation of varying compressive strengths and moisture resistance. The type you want to use is extruded polystyrene insulation or XPS insulation, as it has high compressive strength and is a closed cell foam which means it won't absorb water. Definitely stay away from expanded polystyrene insulation (the white board that looks similar to what you find in packaging), as this is open cell polystyrene and will absorb water and eventually break down. It also has very low compressive strength. The other type of insulation you may find is polyisocyanurate or polyiso insulation, this is also a poor choice as it is not resistant to water and will break down with exposure to the elements.

I've found that extruded board generally runs about the same price per inch wherever you buy it. Home Depot, Lowes or any of those will likely be your best choice. You could also check out roofing or siding suppliers, some of them may sell to you, although not sure if it will save you anything. Hope this helps.
 

rob.mwpropane

In The Industry
Jun 9, 2015
201
Baldwin, Maryland
I used 1" extruded insulation, taped the seams with sheathing tape, and then covered it with a layer of 60 mil EPDM roofing membrane (similar to pond liner material) under my Intex 12x24 Ultraframe. The membrane was likely unnecessary, however being in the roofing industry, I had it laying around so I used it. I've had the pool up for 5 years now, left it up through the cold northern winters, and the bottom is as smooth and flat as the day I installed it.

One thing to mention about "foam board", there are a few different types of rigid insulation of varying compressive strengths and moisture resistance. The type you want to use is extruded polystyrene insulation or XPS insulation, as it has high compressive strength and is a closed cell foam which means it won't absorb water. Definitely stay away from expanded polystyrene insulation (the white board that looks similar to what you find in packaging), as this is open cell polystyrene and will absorb water and eventually break down. It also has very low compressive strength. The other type of insulation you may find is polyisocyanurate or polyiso insulation, this is also a poor choice as it is not resistant to water and will break down with exposure to the elements.

I've found that extruded board generally runs about the same price per inch wherever you buy it. Home Depot, Lowes or any of those will likely be your best choice. You could also check out roofing or siding suppliers, some of them may sell to you, although not sure if it will save you anything. Hope this helps.
Really appreciate the thorough response! It's settled then, I'll just go with 1". That's going to be expensive, lol

Edit: Question, now that you have experience with the 1", do you think it's necessary? If you did it again would you use smaller, 3/4", 1/2" even? Thanks
 
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nick_wa

Well-known member
Jun 12, 2012
87
...
Edit: Question, now that you have experience with the 1", do you think it's necessary? If you did it again would you use smaller, 3/4", 1/2" even? Thanks
Also curious as I was planning to do 1" but 3/4" is quite a bit cheaper where I am.
 

nick_wa

Well-known member
Jun 12, 2012
87
3/4" - $12.50, 1" - $20.00

I live in Ontario Canada where it is $50 for 1" and I can't find 3/4", so we are making a trip to pick up supplies at Menards. Electrical conduit and plumbing PVC is also much, much cheaper in the US at Menards.
 

rob.mwpropane

In The Industry
Jun 9, 2015
201
Baldwin, Maryland
3/4" - $12.50, 1" - $20.00

I live in Ontario Canada where it is $50 for 1" and I can't find 3/4", so we are making a trip to pick up supplies at Menards. Electrical conduit and plumbing PVC is also much, much cheaper in the US at Menards.
Holy moly, $50!!! Maybe I shouldn't complain so much. If I had access to 3/4" for that price I would probably go that route, although everything I've read points to everyone using 1"
 

nick_wa

Well-known member
Jun 12, 2012
87
Holy moly, $50!!! Maybe I shouldn't complain so much. If I had access to 3/4" for that price I would probably go that route, although everything I've read points to everyone using 1"
Sorry, that was $50 CAD - $37 USD for 1" here in Canada. 3/4" is likely fine for me too since I am also using Gorilla pad, but I'd like to hear from other people who have done it!
 

rob.mwpropane

In The Industry
Jun 9, 2015
201
Baldwin, Maryland
Sorry, that was $50 CAD - $37 USD for 1" here in Canada. 3/4" is likely fine for me too since I am also using Gorilla pad, but I'd like to hear from other people who have done it!
Might be CAD, but it's still almost double what it is here. At least you have the pharmaceuticals, eh?!? (no offense meant, love Canada)

I'd like to hear from people that have done it also. I've had both 3/4" and 1" used for different things, and I know the 1" def feels more robust. The only thing I can figure is people use it because it's less likely to snap...
 

Spiderfish

New member
Jul 5, 2015
2
Regina, SK
Really appreciate the thorough response! It's settled then, I'll just go with 1". That's going to be expensive, lol

Edit: Question, now that you have experience with the 1", do you think it's necessary? If you did it again would you use smaller, 3/4", 1/2" even? Thanks
I think it depends on what you're going over. In my case, I leveled the ground well before putting the insulation down, however since I was going over packed dirt I likely wouldn't have been comfortable using anything less than 1". If you're going to leave the existing sand in place and it's good and flat, you would likely be okay with 3/4".

I'm in Canada as well...right now a 4'x8' sheet of 1" butt-edge extruded insulation costs about $50CAD.
 

Poolzzz

Well-known member
Aug 14, 2017
373
Vancouver, BC
My previous pool I used 1/2 inch over packed dirt. No issues. Didn't see any problem that would limit it to 1".

My current pool I have 2" on top of packed crusher run. No issues either. Used 2" for the insulation value.

The 2" was shiplap joint while the 1/2 was butt end. The shiplap joint taped up better. Having done it I wouldn't use a butt end joint given the choice.

Didn't really see any issues affecting thickness so not sure what you guys are worried about?
 

nick_wa

Well-known member
Jun 12, 2012
87
My previous pool I used 1/2 inch over packed dirt. No issues. Didn't see any problem that would limit it to 1".

My current pool I have 2" on top of packed crusher run. No issues either. Used 2" for the insulation value.

The 2" was shiplap joint while the 1/2 was butt end. The shiplap joint taped up better. Having done it I wouldn't use a butt end joint given the choice.

Didn't really see any issues affecting thickness so not sure what you guys are worried about?
I wonder how the tongue and groove would be...
 

slayher

Member
May 1, 2018
16
Jax/Fl
I used the 1” foamular xps from Home Depot. It was expensive, but I must say the floor feels great.
I will say this, if the foam you get has the “easy break” seams like the corning Owens does, you will see the lines from those show up after a few days of the pool being filled..... but they are not really different from the tape lines taping it together. Butt joints sucked, the overlap or tongue and groove seems like it would be much better.
 

kwall

Member
Jun 7, 2015
20
belleville mi
I’m replacing my liner next weekend, this is the first time I heard of using foam board for the floor over the sand , anybody have pictures, sounds like the floor would be smoother .
 

slayher

Member
May 1, 2018
16
Jax/Fl
It’s flat and smooth with the exception of the tape lines from using 3 rows of tape on all the joints. I could take a pic, not sure how well the “smoothness” of the floor will show. It’s great though, no lumps, or dips, basically flat.
If you are replacing a liner, you’ll be in a better spot than me. We had to dig out into hard pan, with a lot of clay. So even though my surface was level, I found that it was really uneven. The foam took care of this except where the joints didn’t line up. That took extra work. If you already have sand, smooth it out with a board, and the foam should go over that great. Just remember you’ll still need a cove, I used the foam coving from amazon.
 

kwall

Member
Jun 7, 2015
20
belleville mi
It’s flat and smooth with the exception of the tape lines from using 3 rows of tape on all the joints. I could take a pic, not sure how well the “smoothness” of the floor will show. It’s great though, no lumps, or dips, basically flat.
If you are replacing a liner, you’ll be in a better spot than me. We had to dig out into hard pan, with a lot of clay. So even though my surface was level, I found that it was really uneven. The foam took care of this except where the joints didn’t line up. That took extra work. If you already have sand, smooth it out with a board, and the foam should go over that great. Just remember you’ll still need a cove, I used the foam coving from amazon.
What foam are you using, I don’t think I wanted anymore thickness then 1 inch