Foam board bottom

#1
Hi 😊. Just joined today. Have a 22'x54" Coleman still in the box. Trying to get ground and 12"x12" concrete footers level. Read all of the posts on foam board bottoms last year. Sounds like a good plan to me. But I think I bought the wrong boards. I have 3/4" x 20 1/2" x 8' white styrofoam boards. Before I go to all the trouble of taping them together please let me know if I need to get different boards. Thank you!
 

Pv2

LifeTime Supporter
Aug 14, 2013
410
south east Arizona
#2
20.5 inch? That is going to be a lot of tape! I think people use something other than what I did but mine are the white styrofoam boards with mylar on one side. I used inch thick 4 x 8 ft and probably wouldn't bother to use it again unless maybe I was installing on concrete. I am not in the majority here about padded floors. I just don't like it. I would use a gorilla pad or other protector but don't care for the "cushion" sensation.
 

scout123

Well-known member
Feb 18, 2018
89
Chattanooga, TN
#3
You want to use the extruded polystyrene (XPS) and not the expanded(EPS). I believe the XPS comes in the different colors. The EPS is not as waterproof and can crumble around the seams or corner.
 

Richard320

TFP Expert
LifeTime Supporter
Jan 6, 2010
20,327
San Dimas, CA (LA County)
#4
The stuff you want is going to be blue or pink and it's like one gigantic pellet. It's just one piece. The white stuff is called bead board and you can usually see where the beads were smashed together. They come apart.

Not sure what it's like in Florida, but that extruded stuff is really hard to come by in SoCal. If you can't find it, then you won't have much choice but to use the bead board. I'd trim it real close after the pool is filled, so nobody steps on it and starts breaking it up.
 
#5
Thanks for your reply ��. Yes I'm thinking it's going to be a whole bunch of taping. These are just plain white styrofoam boards. Pool is going in back yard - no concrete. The biggest draw for me to using styrofoam was the smooth bottom - no footprints to try to vacuum

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And that was supposed to be a smiley face - not sure how I got 2 question marks?
 
#6
Thank you! I will try Lowe's and Home Depot again. I went to one and the guy who helped me just thought I'd lost my mind (from the look on his face) and said they didn't have what I was looking for. I do plan to cut/tape together so that it just fits under the pool. I also purchased roofing felt for one layer and enough weed proof to do a layer under and a layer over the foam boards.
 

Richard320

TFP Expert
LifeTime Supporter
Jan 6, 2010
20,327
San Dimas, CA (LA County)
#7
Thank you! I will try Lowe's and Home Depot again. I went to one and the guy who helped me just thought I'd lost my mind (from the look on his face) and said they didn't have what I was looking for. I do plan to cut/tape together so that it just fits under the pool. I also purchased roofing felt for one layer and enough weed proof to do a layer under and a layer over the foam boards.
I just saved you some running around. Lowes only has 1/2" in stock. Home Depot has the 1". This stuff: Owens Corning FOAMULAR 150 1 in. x 4 ft. x 8 ft. R-5 Scored Square Edge Rigid Foam Board Insulation Sheathing-20WE - The Home Depot
 

scout123

Well-known member
Feb 18, 2018
89
Chattanooga, TN
#11
Just an FYI, I know a lot of people recommend using the gorilla tape for the seams. I love the foam bottom. It does keep it smooth, but it's also comfortable to walk on. I like the cushion feel to it.
 

bse53

Active member
Aug 2, 2013
41
Moses Lake, WA
#12
Either the XPS (usually pink or blue) or EPS (white) will work. XPS has a slightly higher density (Foamular 150) than EPS, but only a couple of psi.
Both are manufactured from the same material (polystyrene resin) through different processes, both are closed cell and both will work below grade, so moisture won't degrade either, though some brands of eps foam will absorb more water. Sunlight (UV) will degrade both, though, so you either want to cover it or trim the exposed areas. Home Depot sells a brand of EPS foam that has a reflective film on one side and an opaque film on the other that protects the board.
 

Pv2

LifeTime Supporter
Aug 14, 2013
410
south east Arizona
#14
I am not sure on the tape but folks around here recommend 3 layers of whatever you use, I used gorilla and only did one layer. I have some lines where my foam separated a bit but I don't really care (and I have the "wrong" kind of foam so...)
 
#15
Thank you all SO MUCH for your help. Home Depot is delivering the 'right' foam board today. I will do more than one layer of tape and I'm sure I will be back soon with more questions ;-). Have an awesome day! :)