In Ground Gunite Pool Deck Issues

[germaneighter]

Hi there from just north of Tulsa. I have an in-ground gunite pool about 30 years old. It has a cantilevered deck (I hope that is the correct terminology for a deck and coping all done with one pour....) It is a "Lazy L" design with about 3' of walkway deck all around with one end extending about 10' for laying out or whatever.

The deck has cracked (about 1/2" wide crack) pretty consistently around the perimeter, about 12" from the coping edge, with the exception of a couple places.

My initial thought was to bust up the deck and coping and do another cantilever pour after back-filling and compacting the soil. I had a return water line leak that I needed to repair so while I had excavated I decided to bust out a small section of the walkway deck to get a good idea of what it would take to remove the coping from the bond beam (correct term for top of the pool wall???). There was rebar that ran parallel to the pool through the deck but there did not seem to be any bar running perpendicular through both the coping and deck. After removing the small deck section I could see the coping and how it sat on the pool wall. As suspected the crack was right in line with the width of the pool wall. But the coping seems "bonded" to the bond beam - no pun intended.

I'm hesitant to try demolition on the small section of coping to try to remove it from the bond beam. Now I am having second thoughts about replacing the coping. I am thinking about renting a masonry saw and cutting a "clean" edge just inside of where the crack is now - leaving the coping there and pouring a deck up to the coping utilizing an expansion joint. But I am also worried the coping remnant will eventually come loose from the bond beam. I would also have to repair/patch a few sections of the coping.

Any ideas?

I have a sketch but I'm not sure how to attach.....

[germaneighter]

Well I posted first time a week and a half ago and no replies. What do I need to do to get some action on this forum? Thanks

[PoolDoc]

Most of the users here are pool owners, not pool builders.

I made the decision many years ago to not tolerate standard pool industry chemical advice, and that I would not soft pedal or muffle my rejection of that approach. As a result this forum has never been a comfortable place for 95% of the folk who are in the trade.

It's possible for pool owners to learn enough pool chemistry to become expert in helping others, and this forum has depended on many of those folks over the years.

The same is not true of pool construction. Pool owners DO work with pool chemistry, but 99% of them are never involved in pool construction. That has been fine with me -- I have always considered the focus of the PoolForum to be pool chemistry and operations, NOT pool construction and repair.

However, it remains the case, that the sort of question you asked can only be answered well by someone with heavy pool construction experience.

Your best bet may be to post your question on poolspaforum.com, which DOES have a heavy pool industry user base. But while some there do accept the BBB method -- Waterbear is active there -- in general I would not recommend trusting them for advice on pool chemistry.

[BigDave]

Ben is (as always) right. Only a couple regulars here have any construction experience. I have none - be warned. I'm only posting because I think you're right. The bond beam may be thermally coupled to the "coping section" of the deck. Especially in a generally warm area like "north of Tulsa". What you propose makes sense to me (not a pool pro of any stripe). Cleaving the thermally and mechanically bonded section of the deck from the "disconnected" section sounds reasonable. Just my two cents.

[germaneighter]

Thanks Bigdave and pooldoc. Hope I diodn't come off sounding jerky. I'm a big time do-it-yourselfer (read cheap skate). Way back when I was 17 yrs old (38 yrs ago) I paid $150 to bet the front oil seal on my Opel Kadet Ralley replaced - and it still leaked. I figured out how to do it myself.....part cost $5. Since then I would rather screw it up and learn something than pay someone else....(cheap & stubborn).

Pooldoc - I'll check on poolspaforum.com. Thanks for the tip. And I have never trusted any pool shop about my chemicals. I watched my father-in-law do whatever the pool shop told him concerning pool chemicals. He would spend $100 per month minimum and that was 30 years ago. (cheap, stubborn, and skeptical)

[Marin]

If you have a cantilever deck (bullnose) instead of coping, you should have a control joint around the beam of the pool. Typically that's ~12" from the inside edge of the deck's tip. If the builder didn't put one in there, you'll see cracks exactly like what you are experiencing.

You can use a RotoZip type tool with a diamond wheel. Smooth each side of the crack til you are satisfied. Fill the crack with dry sand within 3/4"-1/2" of the top of the deck.

You can then use a self leveling seam sealant (Home Depot sells SikaFlex) to fill the joint. Be careful, it has the consistency of syrup and is very difficult to clean.

We use a commercial grade product called BOSS by Steigmeier, not sure if it's available in retail.

Good luck!

[germaneighter]

Marin,

Thanks for the reply. No control joint was done in original pour. Your plan sounds great but the crack is pretty inconsistent. Also there are areas of the bullnose coping that seem loose on the bond beam (while most seems bonded to the beam very well). Since the deck has basically settled and is sloped down away from the pool I have decided to use a concrete saw to cut a clean edge, which will leave about 10" from edge of bullnose. I can use an expansion joint or pour directly up to the remnant. Can you advise which you think would be better?

[Marin]

Since you have 2 separate pieces of concrete, you need a control joint. Either the black expansion joint stuff at an improvement store, or place a form to remove later and fill the area with seam sealant. For a pool deck, especially that close to the water, I'd go with the seam sealant.
If you pour up against what you leave of the cantilever, come back later and saw cut that joint. For a small job like that, you can put a 7" diamond wheel on a circular saw and use it like a concrete saw. I tape some cardboard to the bottom of the saw deck to help it move along the concrete. If you have curves, you'll need a smaller saw to make it (Roto Zip, or if the curve is gradual, maybe a 4.5" grinder). Even then it will be tough to make a clean curved cut.

If you want to post pictures I may be able to spot some things to help you out.

I'll be off grid til Monday, but would be happy to help then.
Are you confident that all of that 10" of remaining bullnose is sound enough to stand on its own? If you get the deck removed you may be able to spot and secure any voids.

the sloped deck is ridiculously common, at least around us. The dirt at the back end of the skirt deck washes out and the deck falls away from the pool. Makes it quite ugly. I've subbed out a few jobs like that to guys who do concrete lifting/leveling. They make a few core drills, pump in concrete to lift the area, then patch the hole. Too much geometry involved for me to make sense of it. But, a lot of times it's cheaper than a tear out and repour.

[germaneighter]

Marin,
Thanks for the info. Your directions/advice is very clear. I decided to cut the deck/coping 10" in from the edge. I'm using my 7-1/4" circular saw with a 7" diamond blade. It is going pretty well but I can only get about 2"-2-1/2" depth to the cut. I have already demo'd the deck from the cracked joint out. So after I make the cut I give the edge a good smack with a sledge and it breaks off. My problem is it still leaves about 1-1/2" deep of rough deck/coping concrete. (the concrete is 3-1/2" deep and I'm only cutting 2-1/2" deep.) I'd like to avoid renting a big saw because the small saw is very easy to control. It also cuts the curves quite well. I'm thinking of putting the 7" diamond blade on a 7" grinder wih no guard, hoping to get another inch of depth to the cut. (kind of dangerous...) So then I will compact crusher-run gravel flush to the top of the pool bond beam then pour the new deck over the compacted dirt/gravel and it will sit on (overlap) the top edge of the bond beam by about 2". Now I just need to decide if I will use an expansion joint or pour right up to the existing coping remnant then cut a control joint right at the same deck to coping joint. Any thoughts or advice on this plan?

[Marin]

You're welcome, glad to be of help.

Why are you worried about the bottom half of the cut being rough? It really doesn't matter. Once you're done it will never be seen. If you have some areas sticking out enough, just use a hammer and chisel to knock it off. Or just a hammer.

You'll get cleaner finish results from an expansion joint rather than coming back and trying to saw cut, especially on the corners/curves.

Did you have a gravel base before? A lot of concrete guys don't use gravel for decks. I know most of the cores I pull out when drilling for hand rails don't have a gravel base. It's a good idea, just not necessary.

Another though, again not necessary but also not a bad idea if you can. Every 1-2 ft drill horizontally into the coping to run a 2' piece of rebar into so that the pieces are tied together. I'd feel better about that since you're just leaving 10" of the old pour. Only go into the coping about 4", leave the rest out for the new pour. If you don't have the tools for it, Home Depot rents out the drill & bit pretty cheap.

[Watermom]

Marin, you have been very helpful in several threads. Thank you!

[PoolDoc]

I agree.

[Marin]

Glad to help where I can. Helps me keep my memory fresh or evaluate scenarios I may run across in the future.