Introduction: DIY Concrete Swimming Pool

Picture of DIY Concrete Swimming Pool

Building your own pool is not for everyone, but it can be done, with great results. When I got bids around $30,000 , the choice was to build it myself, or forget it.

For around $7000, and a lot of work, my son and I built a very solid 13' x 22' x5' oval concrete pool off our deck.

We built it on flat ground , but it could also be built in a hole and backfilled.

Keeping the plumbing simple also cut costs.

Block pools can have problems because they lacks the steel needed.

We used lintel block (normally used over doors and windows) to wrap rebar around the pool every 8 inches horizontally.

Stacking the blocks with cores lined up put a rebar vertically every 8 inches.

We cut the sides out of the base row of block to let rebar and concrete connect the wall and pool floor.

The result was a pool that could stay solid on the 3 ft. of rock backfill behind our retaining wall.

We plastered and waterproofed the pool ourselves with white surface bonding cement, and 2 years later hired a pro crew to do a finish coat of prettier blue cement plaster.

Step 1: Design

Picture of Design

This pool had to be very strong, because it sits on backfill in an earthquake area next to the Sea of Cortez. The backfill was all rock, not dirt, which settles.

Block pools can have problems because they lack horizontal steel and they can leak where walls meet the floor.

Curved walls are much stronger than straight, so I chose an oval. I wanted #4 rebar every 8" vertical and horizontal in the walls and continuous through the floor. This is impossible with standard block, but lintel block has notches which let you add horizontal bars every 8"

We kept the pool 30" away from the retaining wall to allow access for plumbing and pump.

To use a small spa 1/2 hp pump we kept the 2"return and 1.25"supply lines large and close to the pump.

A cartridge filter completed the plumbing.

Waterproofing comes from the cement plaster inside a pool. Any crack in the structure means a leak, as the crack will continue through the plaster.

We used fiberglass reinforced plaster inside and out to hold the blocks solid until the concrete was poured cured. This alone waterproofed the pool.

Step 2: Structural Steel Reinforcing

Picture of Structural Steel Reinforcing

Once the ground was flat, we poured a shallow footing for the block. This was to stabilize the walls until the floor/wall cores were poured. The pool weight load is spread evenly on the pool floor when filled with water so the strength this footing is not important later.

One row of block was set in mortar below the pool floor as a level base for the rest.

We ground all the block flat top and bottom. Then we glued (construction adhesive) one row of lintel block with inside cut out level with the soon to be 6" thick floor. A bent rebar is fed through every core, overlapping the 1' on center rebars in the floor. Every horizontal row of block gets a rebar in the notch of the lintel blocks, making a continuous rebar circle every 8 inches. The result was a pool that would stay solid on the 3 ft. of rock backfill with no wall/floor crack. The floor and wall cores are poured at one time.

Step 3: Wall Stack and Plaster

Picture of Wall Stack and Plaster

We drilled holes in the blocks for all the return and pressure pvc pipes, and cemented them in with expansive cement. Fittings are available to point the water flow in the direction you want it to circulate.

A floor drain tube ( 2" in our case ) gets positioned at the low point of the pool. Your temporary screeds should all go downhill to this drain so crud gets pulled to the pump/filter.

Installed the pvc return weir with expansive cement following their instructions. Normal cement shrinks, and leaves a crack.

Blocks are stacked with no overlap so cores match up. Any rebar is overlapped a foot and tied with wire. Blocks are stacked to the waterline. The inside and out of the block is plastered with 1/16" minimum thickness surface bonding cement to hold the block while concrete is poured. A rubber float makes spreading this easy. It dries quickly, so mix just a little at a time, and clean tools every 10 minutes, or kiss them good by.

Surface bonding cement (it has latex glue and glass fibers in it ) holds blocks better than mortar, and also waterproofs the wall. Our pool was was waterproof with a second coat on floor and wall after the pour.

A solid 12"concrete bond beam gets formed with 14" plywood. We wanted a vanishing edge so that part is formed an inch below the final water line to leave room for tile. This edge needs to be angled (we did down on the outside ) so water will not sit on the tile. We built a large catch basin below the edge, but I won't get into that. It is not easy to design the size of the basin.

Now you are ready to pour wall and floor.

Step 4: The Pour (get a Pumper)

Picture of The Pour (get a Pumper)

We pumped ready mix over the house and first on the floor, then into the cores and bond beam in a continuous pour. Without the pump, you need a dozen strong men to hoist the concrete up in buckets- It is a lot of concrete, and you have to do it without stopping. The concrete cannot be runny, so you need a spud vibrator to consolidate the concrete in the cores and into the floor pour. You can rent these, or buy one for $100 at harbor freight.

The concrete should be 6.5 sacks/cubic yard and have both fibers and a water reducing superplasticizer admix. The pumper will want to add water for easy pumping, but you should add more water reducer instead of water. Too much water and you will get shrinkage cracks.

Remove any rocks or bricks holding up the rebar. The rebar must be in the middle of the 6" floor. Too high or low and it will rust and break the concrete.

Leave the surface rough, as in broom or wood float finish. The plaster bonds much better to rough concrete.

Cure the concrete for a full week. The floor is easy- flood it the next morning. Leave the bond beam forms on for a week and keep the top moist. The plaster on the walls keep them moist.

Step 5: Plumbing

Picture of  Plumbing

It can be as simple as hooking up an above ground pool pump and filter with hoses over the edge.

We did ours with conventional pvc and a 20 year old 3/4 hp spa filter pump, later replaced with the same size, but two speed. You don't need a big pump. It just uses more electricity.

Step 6: Steps

Picture of Steps

If you do steps add them after the pour and the area below them is waterproof. They can take a lot of concrete. Next time I would go for narrow steps and more pool space. We poured a layer ( step) at a time and ended up adding lots of rocks and bricks as filler inside the concrete.

Step 7: Deck

Picture of Deck

Since our pool was free standing, we added a deck on two sides, all conventional concrete that overlapped the pool edge, leaving us with nice spot to enjoy the sunsets of San Carlos, Sonora, Mexico.

Approximate Costs

Lintel Block $600

Concrete 21 yards @$140/yd $ 2940

Steel $440

Plaster $160 (We made our own)

Glue $70

Pump $240

Filter $180

PVC plumbing $280

Total- about $5000

+ heFinal plaster and edge tile $2400 (two years later by pool plaster contractor- It is much prettier and smoother than my plastering )

Comments

EmpressYeti (author)2016-03-22

Hooray! I've been trying to convince my husband to let me dig a pool into our hill (not nearly as steep as yours), and your gorgeous success and ambition gives me the science behind my daydream! Thank you so much. I know its a lot of elbow grease and heavy lifting, but now I know it can be done!

gravityisweak (author)2015-09-09

Awesome pool! With a view like that, I might have added a window to it!

I considered the window, actually a salt water see thru aquarium section of wall, but reality set in and I cleverly ignored the idea.

mklodnicki (author)2015-09-10

This is the coolest project I've seen on Instructables. Great info on the concrete work. Thanks for sharing.

jerryjaksha (author)mklodnicki2015-11-25

Thanks! I will put that compliment on the refrigerator.

Once I realized I could use lintel block so the rebar would encircle the pool, every thing else fell in place.

AdyA3 (author)2015-11-01

I built my in ground pool with my son around 8 years ago. It is very similar to yours and I made a couple of mistakes. I made it too deep, only 1.2 mts high water level would have been better for keeping warm, kids playing and well swimming is the same. I added a 2" water solar heater on my roof, used cheap irrigation pipes and they pump to the roof during the day every 30 minutes for 5 minutes draining back into the pool via the filter etc. Your place looks great. I live in Costa Rica and we have had plenty of 6+ earthquakes and no cracks. Sadly the kids get bored with it and it is used just a handful of times a year. I always dreamed I would have a pool in my house and it was only possible by doing it myself. Your home is better with that pool. I added a roof over mine to stop leaves falling in from nearby trees and sunburn. The roof has skylights and cheap drain pipes in a spiral to heat up the pool. At sunset it is the perfect end to the day with a cold beer. Don't listen to folk saying no, they often never do anything let alone such a challenge. WELL DONE!

CarmelC (author)2015-09-10

Thanks for sharing this wonderful project! An inspiration. :)

pierremaricq (author)2015-09-09

great instructable!

WWigderson (author)2017-07-13

Absolutely beautiful! Too bad can't find a man with as much motivation as you! Your other half must be proud!

joeldovev (author)2015-11-29

This is really amazing. So innovative and functional and it looks really incredible. I was curious how long it took you to plan and how long the actual construction took. Did you draft your design/plans out first? And if so, did you have to make adjustments on the way? I really can't overstate how amazed I am at this. Well done!!!

jerryjaksha (author)joeldovev2017-07-02

It was built during the time I built the house. No Idea of construction time, but lots of design time and research on concrete tanks.

jerryjaksha (author)joeldovev2015-11-30

I planned the construction after reading about the " Besser Block " pool walls made from blocks made in Australia. Rather than ship blocks to Mexico, we used local lintel blocks and cut out sections of them for the floor / wall intersection. I have used surface bonding cement before and been very impressed.

It was planned out to the max - many pages of ideas and notes, and research on reinforcing/building concrete water tanks. That is all it really is- an easy to form, strong, watertight tank.

JoannaE7 (author)2017-03-06

did u use gravel for your retaining wall? or just cement and sand?

jerryjaksha (author)JoannaE72017-07-02

used my standard concrete mix - 1part cement, 1 part sand, 3 parts gravel.

jerryjaksha (author)JoannaE72017-03-06

It was concrete- cement, sand, and gravel + rebar.
Sand and cement mixes are not strong and get lots of shrinkage cracks.

DonaldD44 (author)2016-07-25

Very nice pool!

I built my own concrete pool, but it's hot tub sized, much smaller. I found your article while looking for pool coatings. I originally used Drylock waterproofing paint, which worked initially, but developed cracks at the seems between the blocks. I re-painted numerous times. Then the paint began to break off in large chips. Now I am removing all that old paint with a masonry hammer and an angle grinder. Lots of hard work. Once I remove all the paint down to the bare concrete, I plan on re-coating it with something and I am looking for the right product.

Could you explain the "plaster" that you used?

Thanks!,

Don

Pics show condition now and whole pool several years ago.

jerryjaksha (author)DonaldD442016-07-25

Standard "surface bonding cement" will work. Remember that surface prep is the most important. Paint a latex glue on that is 100% acrylic based and surface bond while it is wet.
For a small pool I would consider buying the premix pool plaster from a pool building company. To that I would add alkali resistant glass fibers from a ready mix company (maybe home depot) so that the mortar joints of the blocks are bridged with the fibers.
You can mix your own from my formula (in the comments), but it requires a number of materials you might find hard to get in small quantities.

paravieille (author)2016-07-11

Well done, I love the view on the end shot. Amazing.

lewisfelmingham (author)2016-04-12

hi jerry
great pool and top work getting it all together.
i am about to build similar in indonesia based on (maybe the same) an ozzie companies design and your instructable.

things are hard to come by in indonesia and i am troubled by the seal/plaster coat.
people are telling me to use beton mix with epoxy... any thoughts?

next question: the pool i will build is much smaller and rectangular is shape. 1 metre under the ground and .4 above.
as it is rectangular i will over lap blocks which will hopefully give some structural strength along with the steel. the question is whether i need to use as much horizontal steel as u did in the courses or if every double may suffice. the aussie site suggested vertical steel every 400mm or every second core.
should i follow that or follow your lead and reinforce each core?

thanks for yoour time and inspiration. i will post my results once the wife finally signs off on it and i am allowed to get building
cheers

Your 1.5 meter rectangular pool will need as much or more reinforcing as my curved ne. I would use reinforcing every layer and core just because iit is such cheap insurance against future difficult to fix cracking problems. Maybe overkill, but block itself has no tensile strength to resist settling cracks.

I have posted the plaster formula I used in the comments below

Thank you very much jerry and rallen.
I am still in the planning and begging permission stage. This information helps strengthen my arguement.
I will post my results once i get started.

Thanks for taking the time to help me figure out the details.

Many years ago I spent a very long summer building multiple in-ground swimming pools, and decided I needed a less strenuous occupation. I've not heard of anything called beton mix epoxy, but it sounds suspiciously like Bentonite. Bentonite is used to seal ponds and natural waterways. It's a type of clay that absorbs water and swells. It is used as the basis for most cat litter and oil absorbing "dry sweep" in garages. It's use isn't appropriate for most in-ground pools. The epoxy is a premier type of pool paint that is much tougher, and MUCH more expensive than normal stuff, and requires a respirator mask to paint, but can be done at any time. I suggest you use horizontal steel reinforcement bars, or basalt reinforcement rod or rope, in addition to vertical reinforcement. The block doesn't have much tensile strength, and will crack and separate if not bonded together. The Aussie site recommendations are about what we did, tie the rods together in a 1/3 meter (1 foot) grid and use lots of low-slump concrete. Our good friend here double reinforced his pool for solidity and longevity, obviously! :)

jerryjaksha (author)rallen713662016-04-28

I am not familiar with any pol coatings/sealants except the cement plaster in surface bonding cement and commercial pool plaster.
The commercial pool plaster looks good because they acid etch the coating which has colored grains of well graded glass/sand? in it and the colors sparkle. If this is not important, the surface bonding cement will hold the water fine.

Jerry

jerryjaksha made it! (author)lewisfelmingham2016-04-27

HI

I have attached the formula for the surface bonding cement below. You can buy it from many manufacturers. This recipe does not include acrylic latex modifier which is added 1-1 acrylic to water. It comes from a time before latex additives For a pool the latex must be acrylic to work under constant wet conditions. Work with small batches. Once it sets (10-20 min. after an initial remixed preset )do not remix with more water. Just toss any and mix a new batch. White cement seems to work better- finer ground cement.

The Electrobot (author)2016-04-26

That's an incredibly beautiful pool :) Hopefully I would also build one eventually.

Thanks for the ible.

lewisfelmingham (author)2016-04-12

so negative.

jmateosky (author)2016-03-06

nice pool, y nice explantions. 1 question: cement plaster, did you make or buy it ? Can you share any insight on its compusition or what makes it good for water tight-ness.

Gracias

AlexL148 (author)2016-02-08

Thank you a lot for this diy-article! Great job. It's really the best project i've ever seen here. I'm glad you've made what you decided to do. As for me, i've build my own small backyard pool last summer. And it was the big problem to waterproof it. Smb adviced me to use liquid rubber for it. Have you ever used it? These waterproofing products http://liquidrubber.ca/ were used. It's very significant to do everuthing in the right way - chickens come home to roost)

jerryjaksha (author)AlexL1482016-02-08

I have not used any rubber coatings, only white cement plaster modified with acrylic latex adhesive, glass fiber, etc . The full pool plaster formula is in the instructable. Before you paint anything on your pool, think about how hard it would be to remove and re-coat, and be sure to prep the surface properly.

hescoffier (author)2015-09-10

Congratulaciones, buen trabajo.

Pero creo que un terremoto grado 7 puede causar mucho daño a una estructura de bloques. La experiencia en Chile con estanque de bloques es muy mala. Se fractura con facilidad aunque tenga refuerzo en tensores de fierro.

Te sugiero consultar un ingeniero experto en estructuras sísmicas para desarrollar un refuerzo externo que contenga tu piscina.

Imagino que ya hablas español, después de 2 años en la zona no?

Saludos

jerryjaksha (author)hescoffier2015-11-02

Thanks for the congrats.
But in the pool is where I want to be when the quake comes.
Nothing above me to fall on me !

The blocks are primarily a form for the continuously poured reinforced concrete structure. If the pool cracks, and it may, the water will leak out.
There will be many more important things to deal with after the 7.0 quake than an empty pool.

chiroptikitty (author)hescoffier2015-10-31

From Google Translate, for the curious:

"Congratulations, good job.

But I think that an earthquake measuring 7 can cause a lot of damage to a block structure. The experience in Chile with pond block is very bad. It is easily broken even if tension reinforcement iron.

I suggest you consult an expert in earthquake engineering structures to develop an external reinforcement containing your pool.

I guess you speak Spanish, after two years in the zone?

Cheers"

hescoffier (author)chiroptikitty2015-10-31

nice, translation...

dfouts1 (author)2015-09-10

So you used it for 2 years, then drained it and had it refinished? How has the small pump and minimal plumbing worked out over the last 2 years?

jerryjaksha (author)dfouts12015-10-29

The small pump is perfect for the job. I run it at slow speed for 6 hours a day and the water is fine.

Just4Fun Media (author)2015-09-11

The pool looks amazing and great job on the concrete steps and pathways too! It all looks very professional!

Have you had any wicking issues with the cindercrete block? (water seeping through).

We usually use a torch on or peel and stick membrane if the wall is underground or otherwise exposed to water.

Have a great day! :-)

The pool is completely above ground, so no membrane needed to keep ground water out. The plaster inside coat is really what makes it watertight, so no water actually gets to the blocks.

idahojsnow44 (author)2015-09-24

He is not a contractor he is a thinker always has been as long as I have know him. Nice build uncle Jerry! I just stumbled across this site and saw your post. I guess I know where I need to visit. :)

jerryjaksha (author)idahojsnow442015-10-29

HI Jeff

You would have won if you had entered your outdoor concrete bar. You are welcome to come and visit anytime. The water should be warm thru Nov.

xenia003 (author)2015-10-14

Great project! Thanks for sharing! :)

byronmota (author)2015-09-11

Wonderful instructable. I would suggest, besides checking building codes or a structural engineer to assure the soundness of the structure, finding what would it take to turn it into an "infinity pool". That way, the landscape would blend with the water mirror creating an even more spectacular pool.

jerryjaksha (author)byronmota2015-09-14

This is an engineered structure, not in standard building codes. It also has no fence around, so it surely would not be acceptable many places.

It does have an infinity edge- that low area where we hang out with a glass of wine. We only run it occasionally- too much evaporation and spray from the wind.

Jedi_zombie85 (author)2015-09-12

Amazing work guys

opticschief59 (author)2015-09-12

Pretty darn neat. Thanks for posting.

tcd555 (author)2015-09-10

I am curious about building code issues?

JimTheSoundman (author)tcd5552015-09-10

It's Mexico. I'm sure the building inspector is very flexible for those with cash.

BG_instructs (author)2015-09-08

Question; you stacked the lintel blocks vertically on each other without overlapping per layer.

I would have expected you would simply move the second layer of lintels half a block, so the stacking method would be stronger?

Did you also include rebars horizontally in each layer of lintels or only on the top layer as can be seen on the pics?

Great job done, that is really engineering a pool and not building a pool. Congrats.

jerryjaksha (author)BG_instructs2015-09-09

The cores do not line up when the blocks set to overlap on a curve.

The rebar are in every horizontal row as well as vertical in the cores, essential to hold the water load.

pierremaricq (author)2015-09-09

One question Jerry, in section 6, you indicated that "Remove any rocks or bricks holding up the rebar. The rebar must be in
the middle of the 6" floor. Too high or low and it will rust and break
the concrete."

which rebar are you referring too? I am unable to picture it.

jerryjaksha (author)pierremaricq2015-09-09

A 1'x1' grid of #4 rebar reinforces the 6" thick floor. The rocks just keep the rebar 3" up until the concrete is poured, then removed to avoid thin spots in the floor and exposure of the rebar to moisture from below.

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