Silly idea about raising bottom? Or is it ok? Please advise.

[mike2008]

I've got a 18x32ft in-ground lined pool in the garden (approx 1970s intall, a company called Fernden).

The deep end is 8ft - and for reasons of child safety I'm keen to raise the bottom to a maximum of about 4.5 ft.

I've had a contractor quote the job on site ($ many thousands!), and another contractor give a ball-park estimate at a distance (similar figure to the contactor who saw the site).

Because of not being able to afford the huge sums quoted, I'm thinking about doing the job myself - and I had this idea that maybe I could just pour concrete into the existing lined pool, rather than replacing the liner as the contractors were advising.

Now, I know this is not the conventional way - but surely it wouldn't be too bad? I thought that the new concrete base could be tiled, and that the join between the new tiles and the liner of the existing walls could be siliconed?

The way I see it, when in due course the time comes that the old liner on the walls will need to be replaced, it could be cut where it emerges from the new concrete, and a new liner could then be used for the entire pool, including the new bottom. I might be being naive, but surely there wouldn't be any problem with the old liner remaining in place under the concrete base?

Anyway, that's my idea. I'd really appreciate comments / advice (please be gentle in the comments, even if you feel like doing this ->

thanks a lot!

 

[Casey]

Umm. This idea is just not sounding so bright to me.

I am assuming that the water would have to be drained off.. completely!

Vinyl liners shrink after they've held water! If it is drained and concrete poured into it, you won't have vinyl walls to caulk. You'll be pitchin a fit and buying a new liner regardless.

I would take the liner out completely. Fill it with fill to 2" of your desired depth and redo the bottom with vermiculite and have a custom made liner installed, all DIY.

Others will chime in soon.

 

[mas985]

A small child can drown in 4.5 ft water just as easily as 8 ft. so why do you think it is safer? Also, by the time they are 4.5 ft plus a head tall, they should be swimming pretty well anyway. Small children should never be left alone near a pool so to me, there really is no difference in terms of safety between the depths. At least with 8 ft., if they decide to dive, which all kids will do whether you want them to or not, they have a bit more depth to do it in. I wouldn't do it.

 

[mike2008]

Hi Mark,
in both cases i was planning to protect the pool with either fencing or a dome.
but the reason i thought the 4.5 was safer was probably that i prefer the idea of a weaker swimmer being able to stand in the deep end - plus it would be easier to heat a smaller body of water.

any thoughts re: the technical feasibility of the ideas?
thanks!

A small child can drown in 4.5 ft water just as easily as 8 ft. so why do you think it is safer? Also, by the time they are 4.5 ft plus a head tall, they should be swimming pretty well anyway. Small children should never be left alone near a pool so to me, there really is no difference in terms of safety between the depths. At least with 8 ft., if they decide to dive, which all kids will do whether you want them to or not, they have a bit more depth to do it in. I wouldn't do it.

 

[waste]

Welcome to TFP!!

I've done this a number of times for liner pools. We put a new liner in to match the new pool and don't use concrete to do the filling - in of the deep end. I agree with the folks who have answered so far!

You really seem to want to do this - if I can offer more help in either the decision or the 'how to's', just ask and I'll get into detail on what and how I've done it in the past

 

[mike2008]

Thanks everyone for your comments so far.

Dear Waste: Yes - further advise about the decision and the how-to would be gratefully received! In the first instance, if you have further advise about the decision of whether or not to do this, that would be useful.
I take the point about diving being safer, and that a child that is tall enough to safely stand in 4.5 ft will likely be a good swimmer anyway.
On the other side, I think it will make it more economic to heat a smaller body of water (with no heating, our pool water temp varies between about 15-17c in autumn to 21c in summer).
On the other hand again, it sounds quite a big job, and the pool and liner are both working well from a technical point of view at the moment - and there's that saying, if it ain't broke don't fix it.....

So: decisions, decisions! .... any thoughts?

 

[Rob]

How often do you heat? How much do you spend on it?

It sounds to me like that is now really the only reason to do this, to cut back on heating. This makes this a fairly easy process. Calculate how much you currently spend to heat the pool. Figure out how much you would reduce the volume of the pool by, and compare that to the cost of this job.

If you DIY, money wise, you are looking at the cost of the water, fill, vermiculite, and a new liner.

 

[mike2008]

How often do you heat? How much do you spend on it?

I don't know. I only moved in a couple of months ago, and so the boiler's only been running once. (and I've not had any gas bills yet... ) This was after I had spent a couple of weeks of hard work getting on top of a severe algal problem that had developed in the vacant period between house ownerships. Once the water was looking good and tempting I decided to run the boiler all morning and afternoon, and by the evening when I tried to get in the water had raised from about 20c to 23c. I spent about 20 min trying to get in, before finally having a couple of minutes swim in the bracing cold, and making cover back for the house. Maybe my cold tolerance isn't good, but the experience didn't seem ideal...

I'm thinking that if I cover the pool with one of these polycarbonate extendable domes then it might keep the heat better? but maybe the cost of the dome will outweigh the gas bill savings!

Welcome to TFP!!

Thanks! I have actually been "lurking" about on the forum for the past couple of months, since moving into this new property - and as I've never had a pool before, this website has been a great source of information

Any more thoughts about the pros and cons of doing this bottom-raising job?
thanks!!

 

[searayboater]

I don't believe this is a child safety issue. That's what responsible adults and lifejackets are for. A person could drown in as little as 2 inches of water. Save your energy and the money for another project.

 

[waste]

What you are considering is a major change to the pool :|

The folks here have given you good and logical advice, but let me offer what I hope is as good and logical advice.

If you go ahead and do this, a new liner is pretty much a must (concrete and/ or tiles will not bond properly to the liner for long )

The ones I've done have pretty much followed this pattern -

Drain pool and remove liner

Take care of any plumbing issues (bad returns or raising a main drain to the new level) and any wall panel issues.

Add fill material to the desired new depth (concrete would cost you $$, we usually use #57 gravel [aka 3/4" stone] to fill in the deep end) - you want a non / small compaction material, I suppose that sand could also be used.

Put stakes at the defining points of the new bottom and trowel in 2" of vermiculite & cement base.

Install new liner - fill with water and let the homeowner enjoy



This is still a little short on detail, but should be sufficient to let you know what's involved.


As to whether or not to make the pool more shallow in the deep end - it really depends on how you plan to use the pool. Some folks can't stand the thought of a pool that they couldn't dive into, but most of the pools my company builds are the "sport pools" that are more for pool volleyball, getting wet and laps.

Please realize that when the kids are older they will dive into the pool - for that reason, keeping it at it's current 8' depth is ~ preferable.

I'll gladly offer more input as needed, if this isn't enough :-D

 

[MEvan]

Just incase waste wasnt clear enough, the idea of pouring concrete on top of a liner is completely unfeasable. It will not work in any way. You will definatly need a new liner. Ball park bid for that job is probobly going to be between 6 and 10 thousand with liner and raised bottom. You could probobly do it yourself for 3-5 thousand depending on what equipment you ahve access to and hiring help.

 

[cobra46]

As others have said, if you have a pool and non swimming children, you MUST have a fence and/or cover. Children, even young ones, will learn to swim very quickly when given frequent access to a pool.

I would take the money you would spend modifying the depth and buy a solar heating system. Since new ones here if California, you should be able to install your own for way less than $5k.

 

[Hotrod30]

For my 2 cents .... Forget it and save your money.

With swimming lessons my grandkids went from standing in the shallow end to me yelling at them to stop doing backflips off the side of the pool in two years.

They grow-up so fast.

 

[mike2008]

Thanks everyone for your good advice.

I think I'll put my "pouring cement into the liner" plan on hold, and think pressing ahead with other ways of securing the pool from a child safety point of view.

Has anyone seen those polycarbonate covers, that go on sliding tracks, and look a bit like uPVC conservatories? Are they any good?

thanks for your advice,
Mike

 

[gregg123]

We recently built an inground pool with depths 3.5-6.4. After 2 months my kids rarely go in the shallow end. They jump and play in the deep end. If I had it to do all over, I would have less shallow area and go deeper, maybe to 8 ft. The extra depth I think helps keep the water cooler in the summer.

 

[waste]

Thanks everyone for your good advice.

I think I'll put my "pouring cement into the liner" plan on hold, and think pressing ahead with other ways of securing the pool from a child safety point of view.

Has anyone seen those polycarbonate covers, that go on sliding tracks, and look a bit like uPVC conservatories? Are they any good?

thanks for your advice,
Mike

I've just bumped this, but you might want to try that question on covers as a new topic