The DensShield Debate: Is it fine by itself in a shower?

[JohnfrWhipple]

A common debate with builders is my charge to tape the joints, and waterproof the backer board. Remember that Denshield is basically a fancy drywall product and very common on Vancouver job sites.

But is that all you need? This is the debate.

My current project is in Vancouver and features a generous ADA compliant bathroom. Large turning circles. A private elevator. Soaker tub inside the shower. ACO linear shower drain. Barrier free entry. No curb. No dam. Hobless through and through.

I used Noble Company's NobleSeal CIS as the primary floor waterproofing. Brought that up a few inches above the floor and installed it tight to 1/4" Wonderboard Lite.

Weeks later the rough in work was done. So was the insulation and vapour barrier. Then the boards came in and now the tapers are making the place smooth and white. I like my shower build s to be all topical. I like taping the seams of the board. I do not use DensShield very much and on this job was not hired to hang it. I did however price the job to waterproof it.

Here is a peak of how the room looked a couple days back.

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The uneven colour shows the drying of the Ardex 8+9 (dark material on walls). In this picture I'm setting the SK Mesh to tie the walls waterproofing onto the tub deck and shower floor. Later we will install an entire slab over the tub deck making this tub an Undermount installation.

To answer the debated question of should you just use DensShield and no extra waterproofing you really need to ask yourself how well you want your shower built. Local code here in Vancouver is fine with DensShield and nothing else. You can drop the DensShield into a shower pan with an Oatley Liner and CanPlas drain. Skip the pre-Slope. Skip any dam corners. And pass with flying colours the flood test. Hell you can even fill the shower up five minutes before the inspector shows up - it's all good.

But is it right? That's the debate.

It's not. But it's fine. It's included in the price. It's fast. And you can always redo the shower later, say in 3-5 years.

 

[Vegas_sparky]

I don't know if its good enough in a shower on its own, but I know they don't call it itchy board for nothin.

I watched an architect lay on a pile of the yellow Dens stuff, basking in the sun, and his design accomplishent. If the guy wasn't such a douche, we would have warned him. I guess its not itchy on paper. HA!

 

[Sponsor]

 

[ShowerDude]

looks like youve got some dens and diamond rock in their...........at the core of the product is gypsum. any cut edges can and will wick water and turn to mold at some point. unless of course you do A John whipple ardex job on it!

i now only use dens just outside of a wet area in place of greenboard or mold resitant gypsum, and on shower ceilings with good headroom that will be painted....even then silicone seams before i tape. but im crazy and worry about my clients home!

i see it as an upgrade to greenboard only.

 

[Jadnashua]

What local inspectors will pass verses what the industry guidelines call for are not always the same thing. In Massachusetts, they seem to like copper pans, flat on the floor. A good craftsman builds things per the industry guidelines, not the local 'norms' if he wants things to work well for a long time. All of the cbu manufacturers call for taping the seams, but there are numerous industry approved methods to prep the space without surface waterproofing. Personally, that is the method I prefer, but they all will work if you follow the instructions, and again, that is not always the local 'norm'.

 

[JohnfrWhipple]

This is the stuff we see in Vancouver.

I tape the seams and then later gave the job two coats of Ardex 8+9

This fellow used Mapei's HPG on the seams and screw heads.

That's the wrong fleece fabric for HPG. Looks like Mapei's fleece for Aquadefence or Laticrete's HydroBan

 

[JohnfrWhipple]

looks like youve got some dens and diamond rock in their.................

Just the single sheet of Diamond Rock or whatever it's called. The stuff is bumpy. When I taped the seams I skimmed out the part of the Diamond Rock that was getting the Ardex 8+9.

 

[Eurob]

John , I've used both -- the good mesh and the wrong fabric -- with the HPG . The fabric is a little harder 'cause the fibers keep '' lifting '' , but it is not that bad -- works better for changes of plane -- . The other mesh -- gets you a good thickness for the first coat , but lots of pinholes.

What do you think is the thickness of the built-in acrylic coating for the Denshield ?

I've heard that there are very few mortars which can adhere properly to the diamond rock . A coat of Ardex 8+9 should take care of it .

 

[JohnfrWhipple]

Thanks Roberto. The water resistant layer on DensShield is quite thin. I don't like it. I too have tried a number of approaches with HPG. That stuff sucks. Too thick and the colour bugs me. I don't know why. I see so many people using it like Hydro Ban or Red Guard. It's suppose to be a one step system with mesh. Most stores that sell it don't sell the mesh! WTF is up with that. Poor bastards buying ingredients for a shower but not having access to required items.

I have found Ardex 8+9 bites very well to DensShield but I was unsure of the bond with Diamond Rock. That's why I flat trowelled it with some 254. I left that two days. I know 254 bites to Denshield very well. I know Ardex 8+9 bites to 254. Step one. Step Two.

It looks tight now. Tile is being purchased and the tile crew will be banging out this room soon.

I did a job a few years back where we used some Aquadefense over Denshield and found that under stress the bond is not that great. What happened is that the framers built a wall where was to be none. Then the boards hung DensShiled on the framing. Silly me I thought the wall in the shower was to be waterproofed. So I tied in my NobleSeal TS shower pan into the walls with Aquadefense (that was back when I still used liquids).

The builder caught the mistake after all the work was done. Then called me, the framer and the boarder back to say we $^&&^ed up. So the framers came back pissed off and just ripped out the wall. When they did the Aquadefence peeled away quite a bit. That is when I learned how poor the bond is to many backer boards.

When I flat trowel I work the thin set back and forth. I think the tiny aggregate in the thin-set helps add tiny scratches to the surface and improves the bond.

 

[JohnfrWhipple]

One this project years back I had no access to the mesh over a long weekend. I used two coats of HPG.

First coat hit the screw heads and corners. Niche too. Second coat saw me do the entire shower.

This was a Proline install. The pan had a NobleSeal TS base. I covered the entire shower so the inspector would only see one product. Sometimes that's easier than showcasing new items to our local inspectors. Years later I leave the TS or CIS uncoated. I think now I have copies of Noble's approvals in every city but West Vancouver.

 

[Eurob]

Thanks Roberto. The water resistant layer on DensShield is quite thin. I don't like it. I too have tried a number of approaches with HPG. That stuff sucks. Too thick and the colour bugs me. I don't know why. I see so many people using it like Hydro Ban or Red Guard. It's suppose to be a one step system with mesh. Most stores that sell it don't sell the mesh! WTF is up with that. Poor bastards buying ingredients for a shower but not having access to required items.

I have found Ardex 8+9 bites very well to DensShield but I was unsure of the bond with Diamond Rock. That's why I flat trowelled it with some 254. I left that two days. I know 254 bites to Denshield very well. I know Ardex 8+9 bites to 254. Step one. Step Two.

It looks tight now. Tile is being purchased and the tile crew will be banging out this room soon.

The thing is , John , that some say -- not pointing fingers -- HPG does not need the mesh or the fabric . The DS says differently ....and there is no way to use the mesh and the HPG in one coat and not have pinholes ....... unless you are '' saying '' , oh , they are only surface pinholes , not going all the way through . I know that 2 coats are a minimum and you cannot build it thicker without having the pinholes effect .

Not the first time I hear stores are not selling -- as a unit -- the fabric or the mesh along side the liquids .


The Ardex reps are extremely confident in the 8+9 to bond to almost every impervious material -- glass , porcelain , fiberglass mesh -- and the Diamond Rock should be one of them -- included -- . I wouldn't hesitate to apply the 8+9 to it directly .

 

[JohnfrWhipple]

Thanks Roberto.

HPG to my understanding is a one step system. I took a training course at Mapei. Maybe I'm mistaken.... Pretty sure I'm right.

On the photo I showed I did two coats. No mesh. But my DensShield was pre taped and I had bonded NobleSeal TS up the wall 6"

http://www.mapei.com/CA-EN/Tile-&-Stone-Installation-Systems/Waterproofing-Membranes/Mapelastic-HPG

 

[JohnfrWhipple]

Just read the link below and it says HPG is only approved as a waterproofing system when used with the mesh.

http://www.mapei.com/public/CA/products/MapelasticHPG_TDS_EA.pdf.pdf

In my training they never showed the use - just described it. I remember Chirping the Suit giving the class that he was wrong when he excluded the mesh from his review. I guess we where both right. The way he described it was OK too - just not approved with a 118.1 rating. My way has the 118.1 rating.

 

[Eurob]

Just read the link below and it says HPG is only approved as a waterproofing system when used with the mesh.

http://www.mapei.com/public/CA/products/MapelasticHPG_TDS_EA.pdf.pdf

In my training they never showed the use - just described it. I remember Chirping the Suit giving the class that he was wrong when he excluded the mesh from his review. I guess we where both right.

The way he described it was OK too - just not approved with a 118.1 rating. My way has the 118.1 rating.

I like that you made the difference -- including the shower pan liner approval -- in between the recommendations !!!