It's roofing paper, for waterproofing roofs. It's under my hardwood floor. It would be waterproof if you tape the seams, I think, but I doubt it acts as an isolation membrane as Ditra would.

It really depends on what you are waterproofing. Is this for a shower?

The bathroom will be a "wet-room" and it's for the floor outside of the shower, and the surrounding shower walls. The actual shower floor or pan will have a DITRA like product that come with the shower kit from proline quickdrain.

It looks like your contractor is thinking of doing hot mopping which will not work well for quickdrain.

The asphalt will not adhere well to the Noble membrane used with the quickdrain. In addition, asphalt will become brittle over time, giving rise to leaks.

The best approach would be to use Kerdi/ DITRA/ Noble throughout.

If your contractor hasn't worked with DITRA/ Kerdi, look for one which has.

If your contractor is doing a conventional shower pan with a chloraloy pan membrane (it's a grey "rubber" looking sheet membrane) then either 15 pound tar paper or 6 mil poly is all that's required behind the cement board as a vapor barrier. If you want waterproofing, I'm sure he could do it, but it would cost more.

I think you only have part of the equation. The roofing felt as mentioned is designed mostly for a hot mop install and I think is layered with "Hot Mop". This is normally done with a standard compression drain and seen mostly in California.

The Proline drain from Quick Drain USA is a shower drain that hooks up to the home's plumbing system with a 2" No Hub coupling - not to a compression drain. Perhaps your tile man is planning to drop the Proline over top of a compression drain ???

Does your home have plywood construction right now? Is there a 2" drop framed in for the entire bathroom?

Many tile setters will install Building paper over plywood and nail down expanded diamond lath over top. The building paper acts as a "Slip Joint" and separates the mortar bed from the plywood floor. The mortar bed is commonly made up of one part portland cement and four to five parts sand.

There could be a poor hybrid installation underway or your tile guy can be right on track with his sloping technique. I think you should ask for more clarification into the process before proceeding.

Can you post any pictures of the current bathroom and the steps being taken?

JW

For the shower walls, just as Bill wrote, felt behind the tile backer board would be appropriate for everything but a steam shower. The felt or tar paper is stapled to the studs, then usually covered with a cement board like Durock or Wonderboard, but Hardie is fine. You then tile over the tile backer board.

For a wet room floor, tar paper won't cut it in terms of being waterproof. Tar paper can saturate and then pass water through its thickness. It's perm rating also changes according to how "wet" it is. So while tar paper would be fine as a "drainage plane" behind a shower wall, it's not the best choice as a "waterproof membrane" for a wet room floor.

But as the other kids have mentioned, if this is getting hot mopped then that's a whole 'nother animal. A hot mopped floor would be waterproof.

Ditra usually isn't installed inside showers, but it's very common outside the shower area for a wet room floor in the non-shower part of the bathroom. To be waterproof, the Ditra seams should be sealed with strips of Kerdi membrane.

Inside the shower (if staying within the Schluter family of products) you'd use Kerdi used instead of Ditra.

However...you're using a Quick Drain, as Davidtay wrote, Q-D has nobel membrane attached to it. I highly recommend sticking with one manufacturer's family of membranes, especially in a wet area like a shower floor that can potentially see a depth of standing water. So if using Q-D I'd recommend using Nobel membrane on the shower floor too. You can still use tar paper on the shower walls.

Once you get outside the shower, you can continue with Nobel or with appropriate considerations you could transition to another material like Ditra.

Noble Membranes are much better because any modified thinset can be used. You should have your tile contractor get you some Noble TS or DalSeal TS and have him set the membrane with Laticrete 255 Multimax and then take your choice of thinset that best suites your floor tile.

Noble and 255 Multimax is a bulletproof combo!!

Todd Stull
Enola, PA

great advice here.

I like that so many various product options were discussed.

Remember that water can slide, seep or leak through anything.
When it appears leakproof, it still might not be.
An example:
http://www.youtube.com/watch?v=hOUUjNwywo8&feature=relmfu

I think further discussion (by katie and her contractor) are warranted.

If she wants a 'waterproof" shower/room then 30# felt isn't going to cut it. Like you guys say, it is appropriate / common / acceptable to use it (as long as it is detailed correctly) - but it will not replace a waterproofing membrane. Putting it behind wall surfaces that will have a waterproofing over them is not the best idea either.

Not sure what the "Ditra like" product from QuickDrain is , but DITRA IS NOT for shower pans!

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Quick Drain USA makes a 2% sloping product. Quick Slope.

Perhaps this is the "Ditra Like" product Katie is thinking of.

If the contractor is going to install building paper down over a plywood subfloor and use expanded diamond lath he could be on the right track.

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We use building paper and diamond lath all the time here in Vancouver.

If the plan is to use the Quick Slope and building paper with the Quick Drain install then I would think using the Flat Panel under the sloped panel makes the most sense.

I like Mapecem Screed Mortar for this step.

Perhaps just using a product like Grani Rapid over a well prepped plywood floor would make for a better install?

Using the sloped panel with traditional 4-1 mix is not going to give much bite to the subfloor...

JW

Wow! Thanks everyone. Your feedback has given my the confidence to have an in depth conversation with the contractor about the right product to use in the space.

Katie

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Here is a tub to shower conversion. On this project we used a traditional 4-1 mud bed with diamond lath reinforcement. Left it for 3-5 days and came back and waterproofed.

The drywall crew walked all over my work so in the end I applied a little HPG over the whole installation.

If your installer has any questions about working with Nobel TS have them call the Nobel Company and speak with Eric or one of the many tec's.

Nobel Company.
Phone: 231-799-8000
Toll Free: 800-878-5788

Here is a link that might be useful: Nobel TS installation instructions

Katie have your install review this video from Quick Drain USA.

A self curing mortar like Granirapid should be used in my opinion if you plan to set the Quick Slope and Nobel TS in one day.

With a wood subfloor installation some extra framing or "Back Framing" can stiffen up the assembly and you should insure your floor meets a L/720 deflection rating if natural stone or large format tile will be used.

Mapei's Mapecem Screed Mortar is a wonderful premium shower pan mortar that can be covered with sheet membranes in as little as 16-18 hours. This with a proper slurry coat makes an excellent filler for those waffles in my opinion. I have used a few roofing nails as well and these can help pin the Quick Slope in position but are not spec'd nor require I believe. With a gently "Love Tap" from a hammer they should be set below the finished height of the panel.

Good Luck.

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Here we set the Nobel TS to the Quick Slope with Rapid Set thinset and the remain shower received Mapecem Screed Mortar - Fast Set.

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Remember when you measure to slope with a one way pitch any "level check" parallel to the drain needs to measure so the level is the same distance from the drain. With the install above my subfloor was a little out of wack so I fine tunned the grade with my Magnesium Float. When working with Mapecem Screed Mortars a Magnesium Float works best as it tends to stick to a wooden float.

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Here is a Nobel TS install. You can notice a couple of patches where i found a slight puncture mark. I did not do a good job of checking my screed mortar and believe I rolled the membrane to hard over a tiny stone. Always check for anything that looks suspect and patch as needed. A simple swatch of Nobel TS and some Nobel Sealant 150 and your good to go.

Let your install dry out for 24-48 hours and then flood test. Here I used a 2" inflatable test plug. We flooded this shower out for 3 days.

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JW

Here is a link that might be useful: Quick Drain USA Installation