Waterproofing Concrete Shell Prior to Plaster

[shashivr4]

As the title of the thread states, what are your thoughts of waterproofing (or damp proofing as some would say) the concrete shell prior to the plaster being installed with a product such as Basecrete?

Does the entire pool require it?

If not the entire pool, how about a raised spa or an exposed pool wall (ex: For a vanishing edge pool or swim-up bar). In these examples, would it be for both the interior (positive) and exterior (negative) sides or only one or the other?

Would love to hear everyone’s thoughts!

 

[cowboycasey]

YES YESY YES, Basecrete is one of them, I am going to use AQURON CPSP.. I am also adding waterproofing to the actual shell concrete.. Anything to stop water coming through the shell is a great thing.. It does cost more money so almost no ones does it... Here is a great PDF for installing an all tile pool and what they recommend..



And most everyone does not know the secondary waterproofing for tile.. I have Mapei Aquadefense and also use it on my tile floors in the house..

 

[ajw22]

As the title of the thread states, what are your thoughts of waterproofing (or damp proofing as some would say)

Can't hurt, may help.

Do it.

 

[JoyfulNoise]

For the bond beam and tile line, it should be standard procedure. For the entire shell, that is not typical. This is a decision that should be made with the PB and the plaster applicator sub. If damp-proofing the shell is not something they typically do, they may refuse to warranty the plaster if you go ahead and do it on your own.

 

[cowboycasey]

For the bond beam and tile line, it should be standard procedure. For the entire shell, that is not typical. This is a decision that should be made with the PB and the plaster applicator sub. If damp-proofing the shell is not something they typically do, they may refuse to warranty the plaster if you go ahead and do it on your own.

That is an interesting take on the subject.. Most Plaster failures are because water gets behind the plaster.. By waterproofing the shell that should stop the water intrusion from behind.. What would be the reason to not waterproof the shell?

I am not doing plaster on my pool and it will be all tile and I have to admit I have gone into the deep end on waterproofing the shell..

 

[JoyfulNoise]

I don’t think I’d make the statement that “most plaster failures” are due to water getting behind the plaster. Plaster is a cementitious material almost exactly the same as the concrete used by the shotcrete crew to make the shell (differences are in the aggregate used and other additives, colorants, etc). So if the plaster is in intimate contact then the interfacial bond should be very strong and there shouldn’t be any issues. This is especially true when both the shell and the plaster are new installations.

I would say that workmanship issues can create voids at the plaster/shell interface (hollow spots) and that water could potentially get behind the plaster and cause issues. But I’m not sure adding a moisture barrier material would make that possibility any better or worse.

If you are doing a tiled pool then I’d say a waterproofing layer is a good idea because you are talking about very dissimilar materials in intimate contact - thinset tile mortar, ceramic/porcelain tile and grout. Fully and continuous submerged tile takes lots of special care in terms placement and so a waterproofing layer may be the optimal solution.

But for plaster on concrete … not so sure waterproofing is necessary.

Perhaps @onBalance has some real world experience with this idea…

 

[shashivr4]

That is an interesting take on the subject.. Most Plaster failures are because water gets behind the plaster.. By waterproofing the shell that should stop the water intrusion from behind.. What would be the reason to not waterproof the shell?

I am not doing plaster on my pool and it will be all tile and I have to admit I have gone into the deep end on waterproofing the shell..

What product are you using?

 

[onBalance]

I concur with Matt. And I don't really see the need to waterproof prior to a full tile pool job.
New plaster is not completely waterproof, which means that some amount water passes through and into the gunite or shotcrete as a normal occurrence. Water behind a plaster coat does not typically cause plaster failures.

 

[JoyfulNoise]

Cementitious materials are fickle things - they undergo both carbonation (calcium lime converting to calcium carbonate) and hydration (Calcium silicate hydrate conversion to calcium oxides and silica). Both of those processes happen in newly poured cement and it is what is referred to generally as “curing”. Both of those processes require water and carbonate (carbon dioxide) to be present. So, in general terms, you have to be somewhat careful about how you control the exposure and flow of water to and from a cement structure as you could, inadvertently, mess up the curing process which leads to a weaker material.

Water incursion is certainly something to be careful with, but it’s best to apply those protections where they are needed most rather than just generally using it everywhere in the hopes that “adding something more” will make it better.

 

[shashivr4]

Cementitious materials are fickle things - they undergo both carbonation (calcium lime converting to calcium carbonate) and hydration (Calcium silicate hydrate conversion to calcium oxides and silica). Both of those processes happen in newly poured cement and it is what is referred to generally as “curing”. Both of those processes require water and carbonate (carbon dioxide) to be present. So, in general terms, you have to be somewhat careful about how you control the exposure and flow of water to and from a cement structure as you could, inadvertently, mess up the curing process which leads to a weaker material.

Water incursion is certainly something to be careful with, but it’s best to apply those protections where they are needed most rather than just generally using it everywhere in the hopes that “adding something more” will make it better.

Great points! Would you recommend waterproofing any of the following:

1) raised spa (tiled interior and exterior)
2) Exposed wall (natural stone exterior)

If so, both the interior (positive) and exterior (negative), or just one or another?

 

[JoyfulNoise]

Great points! Would you recommend waterproofing any of the following:

1) raised spa (tiled interior and exterior)
2) Exposed wall (natural stone exterior)

If so, both the interior (positive) and exterior (negative), or just one or another?

I would recommend using a moisture barrier on any exposed portion of the bond beam around the pool. Tilers typically apply underneath the waterline tile and extend it about 6” to 8” beyond the tile. I would also apply beneath your stone facade on the exterior to reduce the possibility of efflorescence.

 

[shashivr4]

I would recommend using a moisture barrier on any exposed portion of the bond beam around the pool. Tilers typically apply underneath the waterline tile and extend it about 6” to 8” beyond the tile. I would also apply beneath your stone facade on the exterior to reduce the possibility of efflorescence.

Would you consider waterproofing the full shell if it occurred after 28 days (or whatever threshold you were comfortable with for letting it cure first)?

 

[JoyfulNoise]

Would you consider waterproofing the full shell if it occurred after 28 days (or whatever threshold you were comfortable with for letting it cure first)?

No, too much extra expense and work for very little real gain. Pool plaster is waterproof, it’s what keeps the pool structure from leaking. There’s also 10’s of thousands of pounds of water in a pool exerting uniform hydrostatic pressure on the walls and floor. So even if there were a small area of adhesion loss between the plaster and gunite, it is held staticly in place. What is a water barrier supposed to achieve that the plaster itself doesn’t already do? It’s simply not worth it in my opinion and if you ask plaster applicators, they probably would refuse to do it or void their warranties if you insisted.

The only place a water barrier needs to go is behind tiling and other finishing materials above the water line to avoid pop-offs and/or moisture penetration/seepage.

 

[shashivr4]

Off topic question, what is the expected life of a concrete shell? Knowing that the plaster will eventually have to be replaced.

 

[ajw22]

Off topic question, what is the expected life of a concrete shell? Knowing that the plaster will eventually have to be replaced.

50-100 years.

How long do concrete foundations that support buildings last?

 

[JoyfulNoise]

Pool builders warranty pool shells forever because they know the pool shell is the last thing that would ever fail …. Unless you live in CA where the earthquakes will crack them. Then they only warranty them until they go out of business

 

[shashivr4]

My pool builder is unaware of Basecrete. When asking them about waterproofing behind the waterline 6x6 ceramic tile and behind the 1x1 glass tile on the exposed spa, they recommended using a product by SGM called “Sill and Wall Mud.” SGM’s website states it’s a plaster substrate. Can anyone explain what that means and if it would be good to use behind both tile?

 

[shashivr4]

I have finally found someone in the local area who is familiar with Basecrete. They have provided an initial quote of $2,500 to apply Basecrete behind the 6x6 waterline tile, entire exterior and interior of spa, and outside (negative) side of the exposed pool wall for $2,500.

Alternatively, they can do the entire pool for $4,000. Both options would include an acid wash plus a 2 day dry cycle prior to the product being applied. Thoughts on what option makes the most sense?

BTW, the PB has already installed the coping to the pool (unfortunately) so the waterproofing product wouldn't be applied to the top of the bond bean for the pool. However, it would be applied to the top of the spa (which will be a combination of 1x1 tile and travertine (ie: half vanishing edge design).

Also, anyone have any thoughts on whether Basecrete's "Intercept" product needs to be applied first?

Thanks!

 

[ajw22]

Also, anyone have any thoughts on whether Basecrete's "Intercept" product needs to be applied first?

I think Basecrete is sufficient unless you want to take a belt and suspenders approach like a commercial pool.

Look at the Pool Shell System Guide on...

Basecrete Premier Waterproof Bondcoat | Basecrete Global LLC

1 Product, Unlimited Waterproofing Applications

basecreteglobal.com

If you did a primary and secondary waterproofing layer then Intercept could be used as the primary layer. For most residential pools a layer of Basecrete is more then most do.

 

[shashivr4]

I think Basecrete is sufficient unless you want to take a belt and suspenders approach like a commercial pool.

Look at the Pool Shell System Guide on...

Basecrete Premier Waterproof Bondcoat | Basecrete Global LLC

1 Product, Unlimited Waterproofing Applications

basecreteglobal.com

If you did a primary and secondary waterproofing layer then Intercept could be used as the primary layer. For most residential pools a layer of Basecrete is more then most do.

Great...thank you!

Any thoughts on entire pool or the specific areas (waterline tile, spa, negative exposed pool wall)?