Installing 2" Foam on AGP build questions

[MN-CJ]

The TFP forum has been a great resource so far. I am in the process of leveling off my 30' pool area and finishing building a retaining wall because I learned to remove height to match the lowest spot rather than build up would have the best results. My soil here is sandy with no rocks so it has been pretty good so far. We are planning to put down 2" of Foamular 250 (25psi) extruded polystyrene pink rigid foam as the bottom of our pool and I wanted to seek the expertise of others who have done this.

Another pool owner suggested to use 4" solid 8"x16" concrete blocks for my 20 upright posts rather than thin pavers so you had more surface area to hit with the posts's plastic foot plates. Does that make sense?

I assume I would set the top surface of the block even with the top of my foam. This would mean I sink the 4" block in about 2" and lay the foam right on the level surface, correct?

My next question is where should the 2" foam stop? Can the foam run out under the plastic bottom rails running from post to post or should the foam be kept short of the pool wall? I believe the weight of the pool wall is being held up by both the posts and that bottom rail. Given the weight of all of the water, I assume the foam will compress some which would make me think the foam will also compress below the bottom rail but would not be able to compress the concrete block. Is that an issue or is the weight held by the posts and not really the bottom rail?

I believe I read I need to Gorilla duct tape all of the seams of the foam after fitting them tightly. I assume this is still the best duct tape product to use?

I plan on using foam pool cove. Do I duct tape those end seams as well? How about the foam pool cove to the pool wall or foam pool cove to the foam floor?

I appreciate in advance the help!!!

Thanks -
Chris

 

[cowboycasey]

Hey there, great questions..

1. the 4 inch solid blocks will work better, I know because I did not use them and some of mine broke in half...

2. I used 3/4 in foam and works great, is there a reason you want 2 inch, it adds 20 buck per sheet...

3. Gorilla tape is great, the 3 inch extra wide is what I used

4. I took the foam to the edge of the blocks, some have cut out the foam over the blocks.. its better to have the legs in direct contact with the blocks

5. you would dig down to put the blocks even with the bottom of the pool/foam

I hope this helps

 

[Jamison04]

When I did ours I set the pavers flush with the top of the soil. Then laid out the bottom rail and set the wall up. Once the wall was up we went in and laid out the foam panels and cut them to fit snug around the edge of the wall. We then triple taped all the seams with 3" gorilla tape. Then laid the foam cove on top of the foam floor and used gorilla tape at every seam and just a few strips at the top of the cove here and there to hold it down and in place as I knew once the water weighed everything down that the cove and foam floor would press down into its final resting space.

 

[MN-CJ]

This raises another question, did you guys stagger the joints of the foam board?

For triple taping the seams, are you just putting the tape 3 thicknesses so the tape area is 3" wide or are you putting one on the seam and then the other two half on each edge of the tape so it is like 6 inches wide?


Jamison04 - In your example, the foam thickness just removes that little bit of height from the pool depth, correct? This would use the pool wall to help to prevent the seams from pushing apart too.

 

[Jamison04]

I did not stagger the seams. Im not certain but I believe staggering them would require more panels than not staggering the seams.

Yes it does remove a little bit of the depth but so would putting sand in there. The walls do keep the foam in place but just be sure to cut them where they fit tight against the wall so they panels can't shift around.

Taping I went over the seam and then overlapped that first piece on either side with 2 other runs of the gorilla tape. So the taped area ends up being around 6 inches wide.

 

[MN-CJ]

I'm having to wait to finish my install due to 2 of the base resin pieces being cracked and shipping next day. On Amazon it appears there is two different Gorilla duct tape numbers for the 2.88" wide stuff. Is there any glue difference between the white (narrower) and black (6003001)?

It looks like CowboyCasey used black and I think the wider is more important?

 

[Jamison04]

I used the black gorilla tape as that was what was available at lowes. Sucks that the base pieces were cracked.

 

[DarrelB]

The blocks have to be flush to the ground level, large enough to cover across the entire leg width, not just partial, and the thicker the better. Also depends how thick the foam is that you used. I used 12"x12"x4" blocks for mine, 3/4" foam, and a gorilla pad. The foam should not go over the blocks as the weight of the pool will push the legs down through it and not be even all across.

 

[Windylou]

Cowboy Casey, where & how much were your foam boards? And how many? I was thinking 8 would be the exact pool size, so do they go all the way to your blocks? The ones I've priced are like 14 per sheet, and that's not really in my price range. I ordered a pad from Home Depot on June 19 & just realized they cancelled the order the same day bc it was on back order. So I'm needing something fast, so I went back to considering the foam, but I want to say I've seen a lot of others do the 2 inch as well. The pad I was buying was like $113, so I really don't want to go over that. I'm also doing the 8x12x4 blocks bc everyone that's done 2 inch pavers with this pool has had them crack. They're like $1.40 each at Home Depot, but 3 something at Lowes.

 

[Windylou]

I misspoke, I was thinking 16, not 8.

 

[MN-CJ]

You are correct Windylou, the blocks are 8x16x4 thick. These are solid concrete block and weigh 33 lbs each. They seem quite a bit more substantial than the typical thin patio block and it's size gives a little more leeway to hit.

Here is my question....for my above ground pool, the base and legs will sit on the blocks. How much weight or pressure is exhibited down by the pool on the resin frame? I am considering cutting out around the blocks and then running the foam out under these rails so the pool floor and the rails are supported by the foam and each base plate is supported by the block. I am thinking the foam could even be a little proud of the blocks (say 1/4 inch max?) holding the base plates since it could compress.

 

[cowboycasey]

I used 16 foam boards, looks like you need 32 to make a perfect circle but the corners you would not need most of the board, lots of waist... I think the easy way to cut down on waist is buy 32, then lay it out with the least amount of waist, you may be able to return 4 to 8 boards but not sure..

I used those 3/4 inch foam from lowes, they are still perfect 3 years later, they have kind of a tongue and groove to them... This would be 450 dollars for 28 3/4 boards.. The 1/2 foam would be 350...
Shop STYROFOAM (Common: 0.78-in x 4-ft x 8-ft; Actual: 0.78-in x 4-ft x 8-ft) Residential Sheathing Square Edge R4 Faced Polystyrene Foam Board Insulation at Lowes.com

I almost got the 1/4 inch foam, I am not sure how much it will compress (105 tons is a lot of weight) but may be able to get away with 2 of these costing a little over 100 bucks..
Shop Kingspan Insulation (Common: 0.25-in x 4-ft x 50-ft; Actual: 0.25-in x 4-ft x 50 Feet) R 1 Faced Polystyrene Foam Board Insulation at Lowes.com

The water weight from your 30 foot round pool is about 210,000 pounds or 105 tons.. I am not even going to guess on approximate weight each block is holding but its a lot...