Replies

1. 
   BobKovacs | Mar 29, 2004 09:21pm | #1

   First off, with a gunite pool, the gunite isn't the finished surface- it's finished with marbelite plaster or another material to "waterproof" the pool.  

   Second, you don't build a pool with a "slab" and "walls"- you create a continuous shell, which needs to be coved at the corners to prevent buildup of algae, etc.

   Lastly, if you have to ask questions like that, you're in way over your head if you're planning to build the pool yourself.  I'm not trying to be harsh, but building a pool is far harder than digging a hole and throwing in some pipes to move water.  You've got to properly shape the shell, properly size and place the drains, returns, skimmers, etc., to make the water circulate properly, and set the equipment up to handle the system.   To make it even more involved, with an indoor pool you've got to have a major ventilation system to get rid of the moisture and chemicals.

   I know, because I built over 800 pools in Las Vegas for the largest inground pool builder in the country.

   Bob

1. 
   timbouctou | Mar 30, 2004 01:55am | #2

   Thanks for your reply. The pool bottom will flat (5 1/2 feet) and rectangular (18'X 27'). The mechanic will be similar to that of an above ground pool, pretty simple. The humidity (and heating in this part of the world) is being looked at by a specialist. I still want to tackle the construction myself (as I will for most of the house, with advices from an architect and a friend who is a general contractor, neither of them having experience with pools). Any advices or references (web) on how to make it? How to make sure that it is waterproof? Thanks, Michel

1. 
   BobKovacs | Mar 30, 2004 03:31am | #3

   For the waterproofing, you need to consider plaster or an epoxy coating.  You don't want the bottom "flat"- you want some slope to allow dirt, etc., to flow to a drain at a low point.  And you need to cove the corners.  Don't pour a separate slab and walls- tie a cage through the whole thing and do a continuous pour- you can use low-slump concrete and hand-pack it, or use shotcrete.

   Bob

2. 
   VaTom | Mar 31, 2004 05:08am | #4

   How to make sure that it is waterproof?

   Michel, I certainly don't have Bob's company's experience.  What I do have is a good pool guy advising me.  Mine's flat bottomed.  No drain, as is normal here.  The walls and floor have water proofing at the joint.  I'm using bentonite.  As I find vinyl liners less than attractive, and no crew available for a traditional concrete pool, mine's tile over the concrete.  It's also what the most expensive pools here get.  Incredibly cheap to buy if you settle for close-out colors (25-50¢/ft).

   One major factor you will gain is ease of keeping it clean and water-balanced by being indoors.  Mine's 2 lane, 50' long with a curve.  I got the skimmer and lights hardware from my pool guy, but for a little more, Grainger offers everything you need.  As used pool equipment here has no resale value, I picked everything else up for a song.

   Don't know your qualifications.  I build concrete houses.  This pool is a small variation for me and incredibly cheap, compared to commercial pool co. prices.  My cost won't exceed $2500 material.

   Humidity control is probably the trickiest, best minimized by a cover.  My heating will be solar, as is the house.  With the cover, heating is also minimized.

   Good luck.PAHS Designer/Builder- Bury it!

1. 
   timbouctou | Mar 31, 2004 06:09am | #7

   Thanks for your reply and explanation. My pool will be 16 or 18'* X 27'. I also intend to control humidity at the source with a tight pool cover as well as with mechanical systems. How are you building your pool? Like a basement (walls on a footing with a slab, waterproofed using bentonite and covered by ceramic) or as suggested by Bob (like pros do it) with a continued wall and bottom system (no intersection between the slab and wall)?I am also going to install a Badujet stream system ( which produce a current to allow you to swim or walk against).

   In our main house we have an above ground pool (flat bottom) that we use a lot in the summer (we live in Canada!) to play volleyball with the kids or just to relax late at the end of the day. We are now building a second house by the river, in the woods (beautifull area). Since we have short summers and lots of moskitos up here, an indoor pool would make sense for us (and the kids..and the grand kids).

1. 
   VaTom | Mar 31, 2004 05:34pm | #11

   How are you building your pool? Like a basement (walls on a footing with a slab, waterproofed using bentonite and covered by ceramic) or as suggested by Bob (like pros do it) with a continued wall and bottom system (no intersection between the slab and wall)?I am also going to install a Badujet stream system ( which produce a current to allow you to swim or walk against).

   Yep, like a basement, but no footing.  My walls sit on the slab.  This decision came after a lot of research.  I can find no drawback and it's construction that's simple to accomplish.  The bentonite is instead of a vinyl water stop (at the cold joint between wall and floor).  It's just a rope that goes into the floor/wall joint and expands when wet to plug the gap.  This allows me to get what I want without the (unavailable) pool crew.  As far as "like the pros do it" goes, large commercial pools here are normally built the way I'm going.  That's if the client will spring for the tile.  A large step up from a plastered pool.

   Without the plaster crew, I was looking at vinyl (bottom end value) or tile (top end value).  Well, I can manage tile very nicely.  By buying close-out colors it's been very inexpensive.  I always have an eye toward resale and that clinched my decision.

   I considered upstream swimming but dislike a harness and saw no reason, other than the cost of the room, to not have real swimming distance.  This is a 2 lane lap pool.  As pools are sized by number of gallons, I have a tiny pool due to its 4' depth, even though it covers a large area.

   We also live in the woods, but on top of a mountain.  An outdoor pool would be a maintenance nightmare.  Our interest was in year-round swimming, as exercise.  The curve of the pool matches the curve of the house.

   There is one successful concrete pool here, separate wall and floor, that is sealed only with paint.  That has other maintenance issues that I didn't want to deal with.  Tile struck me as the obvious choice.PAHS Designer/Builder- Bury it!

2. 
   timbouctou | Apr 01, 2004 02:47am | #13

   Thanks again VaTom. I am almost too shy to ask...but where do you buy bentonite? Home Depot or a more specialised supplier? I will start looking for deals on discontinued tiles, my wife mentioned that she would like to undertake the tiling job.

3. 
   VaTom | Apr 01, 2004 03:39am | #14

   where do you buy bentonite? Home Depot or a more specialised supplier?

   I've never been into a Home Depot, and rarely Lowe's.  Both of my concrete material suppliers offer bentonite.  Not the readymix companies, but the ones who supply everything else.  Probably whoever sells rebar would have it.  Give a yell if you have trouble and I'll find the mfg., who could undoubtedly tell you where to go.  <G> 

   The vinyl waterstops have nothing wrong with them.  Just need to carefully place them in the slab during the pour.  I find it easier to finish the slab without waterstop protruding from it.  Bentonite is later held in place inside the wall forms with either glue or a few nails.

   I will start looking for deals on discontinued tiles, my wife mentioned that she would like to undertake the tiling job.

   Head for the larger tile suppliers and offer to clean out their warehouse of dead stock.  My last purchase was over 1000 sq ft.  I stuck with 8x8 floor tile for simplicity, although it isn't all quite the same size.  Tile's heavy.  Watch what you're transporting it in.  Plan for a tile saw.

   Good luck.  PAHS Designer/Builder- Bury it!

4. 
   timbouctou | Apr 15, 2004 03:58pm | #15

   Me again. I have searched for bentonite and the 5 or 6 local suppliers (Ottawa, Ontario) that I have contacted don't know about it. Does it come under a brand name? In what form/format is it sold? Clay, dry mix..? Any manufacturer I can contact? Thanks again. Michel

5. 
   BobKovacs | Apr 15, 2004 04:05pm | #16

   Michel-

   Another option is a Preprufe liner.  It's a sheet material manufactured by WR Grace (the Ice & Water Shield people).  You'd line the excavation with it, glue the seams, and then pour your concrete over it.  The concrete chemically reacts with the membrane, bonding it to the concrete.  It's about the most waterproof system you'll ever find- we're using it right now on a parking garage that's submerged 40' below grade, with a water table that flucuates from around 2' above the bottom floor to 14' above.

   Bob

6. 
   VaTom | Apr 15, 2004 07:27pm | #18

   Really interesting.  You're thinking it would work as well to keep water in as to keep water out?  Any idea of the cost?  IIRC, my rope was around $1/ft.PAHS Designer/Builder- Bury it!

7. 
   BobKovacs | Apr 15, 2004 07:34pm | #19

   Well, let's put it this way- the water won't move through it in either direction.  I don't think I would use it to keep water IN the pool- if it's on the outside, the water would get into the concrete, and destroy the rebar over time.

   Bob

8. 
   Piffin | Apr 17, 2004 06:45am | #24

   I can understand the structural reasons why a monolithic withcoved bottom would be the stronger in a variety of conditions.

   I've been reading this through though to see if anyone adressed this issue of groundwater.

   A generation or so ago, maybe in the sixties, a Lot of folks around here had in gropund pools. Found out they didn't work too well. reason given is that ground water will drive the pool up and out of the ground.

   So when a bunch of new folks wanted pools in the late eighties, the locals advised against it, pointed to the older failings, and chortled while the newbies spent money building new pools.

   Most of these newer breed with gunnite construction and lots of drainage planning are doing OK, but a couple have had problems with cracking walls and heaving up out of the ground. I think it is a matter of managing the frost. The pool has to stay partly full in winter so the water counterbalances the forces of the soils and water outside the pool and so the weight resists the efforts of the groundwater to float this big teacup. At some point, all this water turns to ice, in and out.

   It's as much art as sscience. I stay away from them, other than to build the decks surronding them. 

    

   Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!

9. 
   BobKovacs | Apr 17, 2004 01:35pm | #25

   Groundwater isn't a problem as long as you keep  the pool full.  When it's full, the pressures inside and out are equal, or the inside is greater, since the groundwater typically doesn't get to the height of the pool water level.  It's when the pool is empty that the shell can pop out of the ground.

   When I built in Vegas, there was one area of town where this was a problem.  Unusual in the desert to say the least, since the groundwater was typically at least 100' down, but in one area they re-contoured a large parcel so dramatically, that groundwater was around 4' down.  The solution was to put 12" of stone under the pool, set a pump in it do draw down the water table, and put a hydrostatic relief valve in the bottom of the pool.  Once the shell was in place, any ground water would be dumped into the pool by the valve, keeping the shell from lifting.

   When the pool was filled, the valve got capped off.  You just had to remember to pull the caps if you drained the pool, or the shell would lift right up out of the ground.  Of course, then you had an above-ground pool.....lol.

   Bob

10. 
    VaTom | Apr 17, 2004 03:26pm | #26

    I've been reading this through though to see if anyone adressed this issue of groundwater.

    Here in Virginia pools are routinely built with a drain in the bottom.  That's not to drain the pool, but to drain ground water into the pool so they won't float when empty.  We clearly don't have the same freezing problems, but it's not an issue unless the valve sticks closed.  As our pool is inside a well-sited PAHS house, no valve necessary.

    This is one of the reasons I suggested Michel find a pool guy for guidance and material supply.  Then all normal local precautions can easily be taken.  PAHS Designer/Builder- Bury it!

11. 
    Piffin | Apr 17, 2004 11:10pm | #27

    Think you were heard?

    ;) 

     

    Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!

12. 
    VaTom | Apr 15, 2004 07:24pm | #17

    Hi Michel,

    Volclay waterstop.  Here you go:

    http://www.cetco.com/groups/bmg/Tech%20Data/Waterstop-RX%20TechData%20NSF%20Sept01.pdf

    It's a rope that you glue or nail down before doing the next pour.  My application was between the floor of the pool and the walls. 

    Nothing wrong with vinyl waterstops if they are easier to find.  Somebody mentioned dumbbells, but there are several configurations.  I find it simpler to pour a slab without anything sticking up out of it to interfere with my finishing.PAHS Designer/Builder- Bury it!

13. 
    IanDG | Apr 15, 2004 10:16pm | #20

    I find it simpler to pour a slab without anything sticking up out of it to interfere with my finishing.

    Surely you've got rebar coming from the slab into the walls anyway?

    I usually pour a 4" kicker for the walls integral with the slab -- the waterstop sits between the inner and outer starter bars for the rebar in the wall.

    IanDG

14. 
    timbouctou | Apr 16, 2004 03:42am | #21

    Thanks for your reply. I will contact the company tomorrow and ask them who distributes their products in Ottawa.

15. 
    timbouctou | Apr 16, 2004 04:59pm | #22

    Which one of their product did you use RX101 or RX 102? Thanks, Michel

16. 
    VaTom | Apr 17, 2004 02:45am | #23

    The link said that 101 was for 8" thick walls or greater.  102 was for 5" thick or greater.  My walls are 6", therefore 102.  Going to depend on what your walls are.PAHS Designer/Builder- Bury it!

17. 
    JohnSprung | Mar 31, 2004 09:41pm | #12

    Have a look at http://www.xypex.com for a way of making concrete waterproof.  A monolithic pour with proper coves and slope for drainage is the right way to go.

    -- J.S.

2. 
   darrel | Mar 31, 2004 05:59am | #6

   "I know, because I built over 800 pools in Las Vegas"

   So *you* are the reason they're having all of those water fueds out there in the desert.

   ;o)

1. 
   BobKovacs | Mar 31, 2004 01:37pm | #10

   Yup- it's all my fault......lol.  Nothing to do with the 1/2 mile long river in the Venetian, or the billion gallons in the water feature in front of the Bellagio.....lol.

   Bob

3. 
   Poolman | Apr 18, 2004 03:55am | #28

   Anthony/Sylvan?

   untill the circumstances change, my answer will remain the same...

1. 
   BobKovacs | Apr 18, 2004 04:07am | #29

   Yup- how'd ya guess?

2. 
   IanDG | Mar 31, 2004 05:27am | #5

   If the pool construction is concrete and you wish to make it water-retaining then here are a few guide lines.

   Use a high strength mix with the minimum of water compatible with workability.

   If possible, pour the base and kickers for the walls in one piece and use a 'dumb bell' waterstop in all construction joints.

   All formwork ties will also need to be a waterstop pattern.

   Good vibration is the key to a void-free concrete and void-free concrete is the key to water retention.

   I presume that the rebar sizes and placement have been specified by an engineer or someone equally qualified.

   IanDG

1. 
   timbouctou | Mar 31, 2004 06:30am | #8

   Thanks for your advices. Two questions: 1) Dumb bell? Can you explain what it is?

   If I understand correctly, you suggest starting by pouring the bottom (slab) and footing (kickers) at the same time as a single unit. Then to pour the wall on the kikers and use a dumbell waterstop between the walls and the kickers. This way I would have only one joint instead of 2. Am I right? If so back to the first question, what is a dumb bell (and not a dumb belle which would be a totally different subject, probably not waterproof)?

1. 
   IanDG | Mar 31, 2004 07:56am | #9

   It is a continuous rubber strip, about 6" wide and 1/4" thick with a bulge top and bottom. In section it looks like a dumbbell [set of weights]

   It is set in the construction joint so that the concrete comes about half-way up it -- the bulges top and bottom anchor it and it prevents water from crossing the construction joint.

   Obviously the least number of cold joints in the pour the better since they are always the weak spot.

   IanDG

3. 
   Donald_K_Bradley | Sep 29, 2020 01:10pm | #30

   If you want to make the concrete waterproof, you can buy various admixtures and types of cement on the market to keep the moisture away as much as possible. These additional ingredients for the composite material have one advantage, they ensure water resistance at every point of the component. This means that the concrete is still waterproofed even if the upper layers have flaked off.