Owner pool build started - fiberglass partially in-ground

[TKR]

My wife and I are just finishing up a country house which we've built ourselves. I've no experience with pools so any pointers, tips and advice are welcome!

We just got started on a 12x20 rectangular fiberglass pool that is sited just off our elevated rear concrete patio. This will be a partial in-ground pool with a new retaining wall on 3 sides, and the existing foundation wall forming the 4th side. (drawings attached). The 4.5' deep pool has a flat bottom. The pool deck will be a 4" step down from the existing concrete patio, which is a suspended slab, about 40" above grade.

The footings for the the retaining wall were poured yesterday. There is vertical rebar set for the retaining wall. A bond beam will be built into the wall. I am considering pavers for the deck instead of poured concrete, for looks and to have access to plumbing in case of leaks.

The pool arrives next week, to be set on a gravel base by our excavation contractor. Once in place I will do the plumbing and electrical. Then I'll have a mason build the wall followed by gravel backfill. I am ordering gravel for the base. I think #89 crushed stone will be a good choice but have found no definitive answer.

 

[kimkats]

Hi and welcome! Thanks for letting us come along for the ride!

Who will be doing the leveling for the bottom of the pool? That is the MOST important part of this build. Next most important is the compaction of the fill. It needs to be done in "lifts" I THINK it is 4" at a time. We can look it up together and see what the best way it and share what we find.

Did you have an engineer look at your plans for the walls? They are going to also play a huge part in the pool being safe over time.

Kim

 

[YippeeSkippy]

Well, this is an unusual approach for sure. I hope you'll take lots of pictures for us.

As you backfill around the pool, add water to the same depth. No higher or lower than the backfill. This is what keeps your flexible pool aligned and the walls neither bowing inward or outward.

Maddie

 

[TKR]

Who will be doing the leveling for the bottom of the pool? That is the MOST important part of this build.

Next most important is the compaction of the fill. It needs to be done in "lifts" I THINK it is 4" at a time. We can look it up together and see what the best way it and share what we find.

Did you have an engineer look at your plans for the walls?

Hello kimkats. I have an excavation/foundation contract who will be cutting out the base and compacting in 4" of gravel. He will also be here for delivery with the boom truck to make any adjustments for level. The soil is sandy clay and very compact. Is it compaction, or leveling, or both I need to double check?

Yes, I am most interested in hearing/learning of any "best practice" for compaction of the gravel backfill between the pool and the wall.. I was considering using #57 gravel. I know from using it elsewhere that 57 "locks in" well and does not compress much. It seems a bit angular and sharp for fiberglass pool but have read that it is used for pool backfill.

The engineer who certified our house plans said no engineering is needed on the wall as long as I maintain less than 48" of unbalanced fill. Same answer from building department. However I have vertical rebar every 4' along the footing and will get the mason to build a rebar-reinforced bond beam around the wall perimeter.

Thanks for the input!

(edit: attached dig diagram for pool)

 

[ajw22]

What does the pool manufacturer say about a requirement for a concrete collar around the pool?

 

[TKR]

Well, this is an unusual approach for sure. I hope you'll take lots of pictures for us.

As you backfill around the pool, add water to the same depth. No higher or lower than the backfill. This is what keeps your flexible pool aligned and the walls neither bowing inward or outward.

Maddie

Hi Maddie. Yes, maybe it does not seem the typical way to put one in What got us here is that the pool must fit in a rather narrow area between the house and the septic field. That limited us on the size of the pool/ deck, and, we did not want a 4' stairway drop, down to an in-ground pool. On the plus side, we hope to get an "indoor/outdoor" feel with the living area opening directly onto the covered patio, and pool deck.

When adding water and back-filling the pool like you describe, is a water truck needed to keep up with the fill and compacting crew?

....Scott

 

[TKR]

What does the pool manufacturer say about a requirement for a concrete collar around the pool?

AJW - I brought this up with the distributor .... the function of the collar and if it was really needed in this design. He would not go so far as to say it isn't needed, but did think that with 3-4 feet of well drained/contained gravel between the shallow pool and cement block retaining wall, its not going to be moving/shifting.

I have not decided yet but am leaning toward no collar. I basically would be pouring a slab of concrete between the pool and the solid wall. Thoughts?

 

[ajw22]

Viking Pools recommends concrete decking. Concrete should be poured at least 3’ around the perimeter of the pool and at least 4” deep. See...

Concrete thickness around fiberglass pool

I thought we finally had a pool builder but he is saying in order to warranty the pool, he wants to put 5' wide 16" thick concrete with rebar around the pool to the tune of $15,000. Is this really necessary? All of his other prices were pretty reasonable (for our area) and I feel like this is...

www.troublefreepool.com

Some fiberglass pool manufacturer wants 3 feet of bond beam around the pool for warranty purposes. See...

Bond beam/collar on fiberglass pool

i tried gc a fiberglass pool project where I would buy the pool direct from the manufacturer who would install with no concrete, and then Inwould find contractors for the other pieces. In talking to a bunch of local landscapers (who do good work), most of them had no idea what a locking collar...

www.troublefreepool.com

A concrete collar will hold the pool shell in the ground if you ever need to drain the water from the pool for repairs. Without the concrete collar you will run a risk of the shell popping out of the ground. And an example of when you might need to drain the pool is a manufacturer had problems with the gel coat on a batch of fiberglass pools and they needed to be drained and recoated. There are some threads here on folks who had the warranty work done.

Check directly with the pool manufacturer and get their warranty requirements in writing. Verbal comments from a distributor are meaningless.

 

[YippeeSkippy]

When adding water and back-filling the pool like you describe, is a water truck needed to keep up with the fill and compacting crew?

My pool was filled with hoses, not a truck. So they allowed the pool to fill while they worked on plumbing and such. They were keeping the gravel up to the level of the water. When they stopped working for the day they also turned the water off. So it was an on-off thing for about 3 days, IIRC.

Maddie ?

 

[TKR]

Next most important is the compaction of the fill. It needs to be done in "lifts" I THINK it is 4" at a time. We can look it up together and see what the best way it and share what we find.

I got a copy of the manufacturer's installation guide. I am reading it now. Here is what it says about backfill.....
"This process is done in stages, about one foot of water then one foot of back fill. This allows each stage of the back fill to be water compacted."

 

[kimkats]

Well there you go!! That sounds like a great way to do it!

Kim

 

[jimmythegreek]

In a situation like yours no collar is necessary. I would install a small collar if it was mine just to make the coping install much easier AND its handy when you someday drain the pool to keep it ll straight. You are above grade on gravel no issues there. You want to use a pea gravel 3/8 max. It will need compaction as it is not angular to lock but doesn't need much. Nothing like road base needs. Best way with flat bottom pool is to setup screed rails using 1" gas pipe. Shoot with a laser making 3 stripes 20+ feet and acreed between them with aluminum screed or a dead atraight 2x4. Place pool and put a little gravel around the shell to keep in place 6-8 inches. Do what you need to with plumbing electric and add gravel and water every few inches. 2 house hoses feom different taps will fill it up fast. Compact away from shell having the water equal or higher when you do. Doesn't need alot shell side with pea gravel the vibration alone locks and settles it. Make sure the pool height is spot on with finished elevation dont forget coping finished height and pitch away. You will need railings for the wall at that height remember

 

[kimkats]

See that post up there ^^^^^^^^^ you can take that to the bank! Do what he says and you are set to have a great pool!

Thanks @jimmythegreek

Kim

 

[TKR]

In a situation like yours no collar is necessary. I would install a small collar if it was mine just to make the coping install much easier AND its handy when you someday drain the pool to keep it ll straight. You are above grade on gravel no issues there. You want to use a pea gravel 3/8 max. It will need compaction as it is not angular to lock but doesn't need much. Nothing like road base needs. Best way with flat bottom pool is to setup screed rails using 1" gas pipe. Shoot with a laser making 3 stripes 20+ feet and acreed between them with aluminum screed or a dead atraight 2x4. Place pool and put a little gravel around the shell to keep in place 6-8 inches. Do what you need to with plumbing electric and add gravel and water every few inches. 2 house hoses feom different taps will fill it up fast. Compact away from shell having the water equal or higher when you do. Doesn't need alot shell side with pea gravel the vibration alone locks and settles it. Make sure the pool height is spot on with finished elevation dont forget coping finished height and pitch away. You will need railings for the wall at that height remember

Jimmy, I appreciate those details and information. That all makes sense to me for this situation. I will call the excavation guy and pass it along today so he can be ready for delivery. Thanks!!

 

[TKR]

A few pictures are attached showing the footings for pool retaining wall. Gives a bit of perspective on the site and relationship to house/porch.

 

[kimkats]

What a pretty area you live it! Please keep the pics coming!

Kim

 

[TKR]

#78 (pea gravel) and equipment on site.

Pool is a scheduled around noon tomorrow. Goal for morning is to place, compact and level a gravel pad for pool. Then place the pool, level it and build up gravel around the outside to stabilize. The pool will be about 10” in the ground at that point.

Should I put some water in until the retaining place is built and we can start backfill?

 

[TKR]

Pool arrived today and we got it set. We only ran into one minor issue: flat bottom pools are not necessarily flat.

Using helpful information above from Jimmy the Greek, excavation guys had the gravel base (#78 pea gravel) compacted +/- 1/4" level, just before the truck showed up with the pool. Boom truck arrived on time and set the pool in place but... the pool was 2" high at the skimmer/drain end. They lifted it off and raked the gravel to a slight 2" slope. Two more lifts/adjustments and the pool was +/-1/4" level.

Pool shell sits only about 14" below the original grade on a 5" compacted bed of pea gravel, placed on top of compacted soil.

Now.... I have to rough-in the plumbing and electrical. Pool distributor pre-installed the fittings. Hopefully I can get a mason out next week to build the retaining wall around the pool so we can call in the inspection and backfill with gravel. The excavation crew stubbed out a daylight drain and trenched it about 50' to the edge of the property. This will be hooked into a perforated perimeter pipe to drain off any water that gets between the pool and the retaining wall.

 

[kimkats]

SWEET! Sounds like they did it right!

Kim

 

[TKR]

SWEET! Sounds like they did it right!