How hard is it to fix crumbling plaster myself?

[coilerman]

I have a 10’ diameter, spillover spa made of gunite and plaster. A big chunk of plaster fell off the pool last winter and it was impossible to hire a reputable pool plasterer. I ended up finding someone on Craigslist and he did an awful job. Cosmetically it was ugly but I was willing to live with it as a temporary fix until I could find a good refinisher. Then the patch that he applied fell off during the pool season. So I'm back to square one.

I’m thinking of fixing this myself by replastering the entire spa. I am reasonably competent home DIYer. I renovated my own house and used to work in the composites industry if that helps.

How hard is this? I figure I rent an air chisel and hammer out the old finish. Then reapply with a trowel. See photos of original damage and the current state of the spa after the repair failed. You can see that the step above the repaired area is also failing.

Thanks.

 

[JoyfulNoise]

That's a pretty common failure spot on a rolled edge step. Mine failed that way after 4 years and I can see cracks on the other steps in similar spots. It was likely caused by an adhesion failure of the original plaster that led to a pocket forming between the gunite and the plaster. Some thermal or mechanical shock then caused it to crack and fall off. It happens more in attached spas than the pool steps because of the rapid changes in temperature and the much harder to attain quality of plastering.

You really don't want to do plastering yourself. It's a royal PITA and unless you have a crew of guys and the right equipment to mix the plaster and get it into place quickly, you're going to do an extremely ugly job (no offense, but plaster troweling is a bit of an art form and if you don't do it day-in and day-out, you're going to suck at it).

What I would suggest is that you do all the demolition and prep work yourself, then sub out the plaster job. A job like that would be quick and easy for a plaster sub to do in less than a few hours and you can work with them on getting the best surface prep possible so that this doesn't happen again. The old plaster will need to be chipped out down to the gunite shell and the shell acid washed and then cleaned very well with a fresh bonding layer and water barrier applied. Then the plaster can be applied over that.

 

[coilerman]

It's basically damage from the ice that forms in the spa. I live in Canada.

I guess I'll just keep calling/begging a company to do this. The demand for pools here is insane. A friend of mine had a fire in his equipment shed that destroyed all the pool equipment and melted his safety cover and he can't get service until next July!

 

[ajw22]

It sounds like the guy who tried to patch the step did not apply a bond coat before putting on new plaster.

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You are correct that ice caused the cracking. You need to try and keep the water level in the spa to either be way above the steps or below the steps so when ice forms on the top of the water it is not on the step.

 

[JoyfulNoise]

It may be ice up where you are but down here, where water doesn't exist in a solid state and liquid water only arrives at a rate of 10" per year, those same kind of plaster failures happen all the time. The root cause is plaster adhesion failure on the rolled step edge. You almost never see the adhesion failure on horizontal surfaces (ledges) and always on edges down the vertical wall for a few inches to a foot. It's just the nature of the plaster slumping off the gunite surface as it is troweled on. Any temperature variations (freezing or heating) or mechanical pressure (freeze/thaw cycling) can cause the plaster to pop off.

When mine was patched by the original plaster company, it looked really ugly for the first year or so but lightened up with time. The guy that did the patch work basically chipped away all the plaster that wasn't bonded, cleaned away the debris, acid washed the underlying gunite and then applied the plaster patch (no bond coat). It's still holding up but the original crack on the rolled edge came right back. As you have figured out, the only way to fix it is a complete redo of the interior.

If you fully winterize the pool and spa then maybe you need to do it earlier and let the spa surfaces dry a bit and then tarp the spa so that no water/ice can get into it. Use a submersible pump to move water out of the spa anytime it accumulates. I'm not sure where you are located you can keep the spa full without it turning into a solid block of ice and doing a lot of damage.

And yes, down here in the states the pool industry is crazy busy and you can't find anyone to do smaller renovation/fix jobs. Pool builds are being booked almost 18 months out. It's absolutely insane.