I was wondering if any of you are still using more than one type of waterproofing in your showers. I've been using nothing but Kerdi now for about three years, but the cost of it is getting sky high, so I'm looking at alternatives.

I had a chance to buy some Laticrete 2935 today. There are five 6-gallon buckets and five boxes of reinforcing fabric. I can buy all of them at a price of $300 per ($1500 for the lot). I know Harry has done showers with the Kerdi drain, Kerdi on the floor and 2" up the walls, and liquid on the rest, so I was considering trying this as well.

My conundrum is that by the time I buy CBU (which I understand is preferred over drywall with liquid waterproofing) and the 9235, then factor in the cost of the time involved with applying two coats, I'm not sure I'm saving anything over the cost of Kerdi, given the ease of installation.

The one upside to the liquid is that it does not have the overlaps that you get with Kerdi.

I bought one bucket and one box of fabric today, and I'm going to try it out on my own shower this weekend (tile above a steel tub and shower), so if I don't like it, I don't have to buy any more, or if I do I can buy up to four more.

The prices I've seen for one setup on 9235 is from $525-$600.

Why did you choose 9235 over Hydro Ban?

I prefer liquid to Kerdi just because of the corner build up issues. Those preformed Kerdi corners don't help reduce the build ups as far as I'm concerned. The real problem area is the top inside corner of a curb. There can be 3 or 4 layers in that section by the time you get all the Kerdi,band and corner pcs on.

The 9235 wasn't really a choice, it's just that I was able to get it at such a cheap price compared to the retail price. However, if I have to step up to CBU vs. drywall, I'm not sure I'm saving anything.

If it's the same price and about the same amount of labor involved, and I can avoid the corner buildups, it may be worth a try.

The Laticrete rep said 9235 will stick very well to drywall, but he also said he just wasn't 'comfortable' with the idea of drywall in a shower.

I didn't know they made 9235 any more. Their Hydroban seems like good stuff though. I've been doing liquid on walls, with Kerdi on floors for a long time...Ron Holten too...we talked about it a few times...no problems at all. The build up in the corners doesnt seem to be too big a deal when using large format tile...to me anyway. There is a lot of mud behind anyway. THe usual ceramic tile..yeah, it's sucks for sure. Harry sure likes that Wediboard...and I've seen the Kerdiboard..samples at least...which is the same idea. I'm starting to like the idea of Denshield...slap it on, waterproof all the seams and go.

I have been using liquid water proofing for a couple of years now. For the same reasons you have already mentioned. I started with redgard, but lately I have been using Mapei Aquadefense. What I like about this product is that it's extemely fast drying. Ready for second coat in about 1/2 hour and ready to tile within about 6 hours. The disadvantage is that it's really dark, so imperfections and layout lines are hard to see. The reinforcing fabric is a pain, so I use fiberglass mesh.

I use a Schluter drain and 3 coats of water proofing for the shower pan. Getting the mortar bed nice and smooth makes the water proofing a lot easier, so I do my mortar finishing with a steel trowel. Water testing with Aquadefence is after 24 hours.

I see no problem with drywall. If you waterproof it right it will never get wet.

I also used Denshield extensively, but it's not avalable where I live now.

I do the same as you Pete but I skim coat my bed with thinset and mesh tape corners and seams at the same time. The thinset I use is really creamy with no sand in it so it's like using drywall mud. No build ups.
I have tried the Aqua Deffense but I prefer the Hydro Ban. The light olive green colour is really easy to see your layout lines.

Kevin, create a spread sheet in Excel and input the different methods you plan on using. You will see right away where cost and labour may determine the best choice for that particular job.

As an example, I normally use CBU and liquid, but I had a shower reno to do on a 2nd floor in the winter. Even though my first choice of materials was cheaper, the labour factor lost out for the use of Wedi. I could cut all my materials upstairs, no dust and it's waterproofed already. The materials cost more but the labour was the winner on that one.

The word from my Laticrete rep is that they will never get rid of 9235 because it is one of their signature products. I thnk they developed 9235 in the late 1960's, so the name recognition is something they don't want to lose.

$300 a unit with the fabric is a great price. If you keep it stored at a moderate temp and umopened, I think it will keep for something like 5 years.

Two years is the shelf life on it. The bucket I bought was made in May '09, so I should be able to use it all, no problem. I'm going to use it for the first time on Monday on my own tub/shower. If I like it, I may get a couple of more buckets while it's still cheap.

If I was able to use it on drywall, it would be a time and money saver. However, with the cost of CBU, it's going to come out about the same price as Kerdi.

I've got a full shower to do in a couple of weeks, so if I like it, it might be worth the extra cost of the CBU, especially if it minimizes the overlap buildups. We'll see.

Kman, You're right about two years being the official standard from laticrete. I should have clarified that the five year figure was given to me as a realistic "unofficial" number as long as it is unopened and stored at a good temp.

Hopefully you can get this stuff and use to make some money. Good luck!

I was thinking of using a liquid system over CBU and utilizing a kerdi drain assembly. Three questions: 1) I have plywood on all walls (to stiffen 10 foot 2x4 walls in shower) - is there a problem with installing CBU right over plywood as opposed to studs? (maybe with moisture build up due to no air space between wood and cement board?). 2) I know the industry standard for a wood sub floor is to put plastic down with stretch metal under the deck mud for the shower floor base. But, with the liquid membrane at the top, does this create a vapor sandwich? 3) I noticed no one uses red guard. Is there a reason related to performance or is it just a cost issue?

I was thinking of using a liquid system over CBU and utilizing a kerdi drain assembly. Three questions: 1) I have plywood on all walls (to stiffen 10 foot 2x4 walls in shower) - is there a problem with installing CBU right over plywood as opposed to studs? (maybe with moisture build up due to no air space between wood and cement board?). 2) I know the industry standard for a wood sub floor is to put plastic down with stretch metal under the deck mud for the shower floor base. But, with the liquid membrane at the top, does this create a vapor sandwich? 3) I noticed no one uses red guard. Is there a reason related to performance or is it just a cost issue?

Plywood is fine without a poly vapor barrier under the CBU as long as the CBU has a waterproof coating applied to the surface.

A shower pan with a topical waterproof coating will not create a vapor sandwich. You only need enough protection on the shower pan floor to help with mortar curing so that the bare wood doesn't suck the little moisture that's in the mud mix out.
You can use tar paper or 4 mil poly. You don't need 6 mil poly on the floor.

In my area, RedGard is only sold at Home Depot in the small pails for the DIY homeowner market. Most tile installers buy the larger 20L pails at wholesale prices from Laticrete or Mapei dealers.
It's more cost effective for me personally to buy the larger quantity.

After using them all, my number one choice for liquid is Laticrete HydroBan.