Large Pool Deck Cavity

[Wmhendrix]

Imagine a 9'x9'x6' cavity. The top is my concrete pool deck (spanning 9' w/ only a couple of 33 yr old 2x4s supporting it) & 3 of the sides are my pool walls. The top of the pool wall on one side is compromised w/ a crack bc the top deck sank a little years ago pressuring it. I won't get into the whole story bc it's fairly long but we just bought this old house & pool 18 mos. ago & I'm trying to figure out what the best method & material would be to fill this cavity in a way that will support the top deck but not put too much pressure on the pool walls while it cures out. Obviously economics is always a bonus too. I plan on filling the pool before I fill the cavity so that the interior water pressure supports the walls. I've considered a grout pump, vermiculite or some mix w/ it or finally if I can find a foam that would spread out, fill voids, not expand to much & provide structural support to the top deck. If you have any experience w/ such things I'd love to get your ideas. Thx

[Watermom]

Hi and welcome to the forum! Once Ben gets your post moved out into the general section of the forum, you'll get more views from some people who may have some suggestions for you. I just wanted to say hello and let you know that your post has been read and you weren't being ignored! Hope you enjoy being a part of our forum!

[PoolDoc]

William, I'm sorry. I wrote a post, but must have never submitted it.

Send pictures! What you are describing needs to be seen. You can email them to poolforum AT gmail DOT com, and I'll post them. Send more than you think we'll need, and send bigger ones rather than resized ones. I'll select and resize for the web.

[PoolDoc]

Pictures:

[PoolDoc]

Having looked at those pics, I'd recommend borrowing a camera that will fit in the hole, and taking pictures inside the hole.

Without a better idea of what we're NOT seeing, I'd be reluctant to recommend anything.

One of the key questions is, "What caused the original material to leave?"

[Wmhendrix]

There never was any original material. It was built (for some reason) this way 33 yrs ago & the entire inside of the cavity is a gunite bowl, just like a cereal bowl. Once the top deck cracked & pressured the interior pool wall to crack it began leaking water in until it was filled up. It was filled up for years I suppose & it wasn't until I went to repair the crack so I could put in new tile & plaster etc that I discovered that it was filled w/ water to the mid tile line. We just bought this house & pool 20 mos. ago. I had noticed that the crack in the tile line was always wet even 2 weeks after I drained the pool so I cut a hole thru the wall & water gushed out like a pressurized water fall. At first I thought maybe I was on a sring or something but when I drained the entire thing & stuck a flash light in it one night I was able to see it was a gunite bowl that had been bulit this way at the start.

[PoolDoc]

You could fill it with grout, using a grout pump. But, you'd need to do it in layers -- I'm not sure if you could count on the walls holding that pressure if you filled the whole thing at once.

But, if it's all concrete lined, and you don't have structural movement -- I'm not seeing the cracks that would indicate that -- my inclination would be to set in a plugged 2" PVC drain through a hole in the wall. That way, you can drain the water when you need to work on the pool, and otherwise, forget about it.

HOWEVER . . . I am NOT an experienced concrete contractor. I've done some complicated work, and by God's grace it turned out well, but that's not the same as 30 years of experience. Waste and Waterbear may have some knowledge, but I'm not aware of anyone active on the forum currently who is experienced with that sort of work.

You might want to try posting on PoolSpaForum.com, which has more guys in the pool industry than PoolForum does. (I tend to run them off, because they end up trying to sell something, or because they just can't wrap their heads around the BBB method and the CYA/Chlorine chemistry behind the Best Guess chart, and those are both core to how we help people here.)

Just be careful. I've hung around contractors enough at the local pool wholesaler -- they tend not to be the most creative or thoughtful people I've ever known. Some of them are VERY skilled, but you've heard the one about how, to a man with a hammer, everything looks like a nail? Well, that describes most of the contractors I've known. They will apply the tools and methods they know how to use . . . regardless of whether they are really appropriate to your situation. So, post at PoolSpaForum, but keep your wits and critical thinking about you! If you get a recommendation that seems dodgy, you can ask here, and some of us might be able to offer reasonable opinions about whether the suggested methods are appropriate.

Waste can even do that here, probably more easily than he can there (he's a mod there) since he won't PO anyone here by telling you that a particular suggestion is not the best idea in the world.

Also, if you can, I'd really, really recommend better pictures. The ones you sent simply don't have the detail I'd prefer, or that would be most helpful to contractors. In particular, I'd try to get pictures INSIDE the hole. It looks like you can reach in with your hand, and if you can, a camera would fit, as well. Borrow one from a friend, if you don't have one. Or, spend $120 to buy one -- it's worth that much to get better suggestions. (Tie a cord to it, so if you drop it, you don't lose it!)

I'm on my 3rd one -- one dropped, one stolen, and a SX150IS is on on my desk currently -- and I've done over 10,000 shots with them. They WILL fit through that hole, and if you take care, give you some good pictures inside. I've done the inside of filter tanks that way. Here are some Amazon links:

Canon Powershot SX130IS /----/ Canon Powershot SX150IS

Good luck.