Greg's Bathroom Project

[87iroc]

I've been reading alot here lately as we are remodeling our primary bathroom in our house.

We have a 8X8 bathroom. I have already put in a pre-fab fiberglass shower base that is 32X60. I put up Hardibacker board to set the tile to and there is plastic in behind the hardibacker. I did this all before I read about Kerdi on here...

We are going to put up 12X12 tile in a diamond pattern(tried to talk the wife out of it...whaddaya gonna do). We will be putting a stripe of a different smaller tile in the middle of it to break things up a bit.

Around the lower 4' of the rest of the room we will be putting up 6X6 tile as well.

The floor will be 2X2 tile on a mesh or 'glue dot' pattern(bought the tile 2 or 3 months ago, don't recall how its held together, I think its glue dots). We are putting down a Warmtiles heat system under it.

The subfloor is 3/4 OSB with a load of extra bracing we put under it when we were redoing the plumbing and moving toilets/vanities around over 4th of July weekend. The floor joists are 2X8s and we put 2X6 cross braces in alot of the high traffic areas. The floor is very solid.

I put down more 6 mil plastic on the subfloor last night and then put mortar down and 1/2" generic hardibacker(the shower walls are 'real' hardibacker). over it and screwed it down. It is currently drying. I wish I would have thought to ask about the plastic on here before I did it. We did it at the old house and it seemed like a good idea to do it again. I bounced back and forth a couple of times on it. Hopefully it's not a problem.

Over this I will be putting a Warmtiles system and SLC. I plan on putting 1/4" hardibacker in the toilet area and under the vanity so the SLC doesn't have to fill that area too. It will also help give what I think will be a better area for the toilet flange to clamp against.(I'm worried about imperfections in the SLC...had a bad experience with it before, hopefully I'm smarter this time).

Anyway, that's the story...here's the question.

1) On the shower walls, what type of thinset should I use? I have access to Menards and Lowes locally as well as a flooring store that is locally owned. Should I use latex modified, standard with latex additive?

2) Is it OK to use Mastic on the lower 4' on the walls outside the shower? The shower will have doors on it and little to no water should get on the walls...although now that I think about it, behind the vanity it 'might' be a problem. ???????

3) I've read an article on putting down SLC over heating grids, any particular types of SLC to use?

4) What does latex additive do to help the thinset?

Oh, I've done a few tile jobs in the last few years...but this is the first shower surround/tile heat system I've put in. Used both Mastic and Thinset.

Thanks,

Greg

[cx]

Welcome, Greg. If you put that name in a permanent signature line (UserCP/Edit Signature) it will appear automatically in each post.

Originally Posted by Greg

I put down more 6 mil plastic on the subfloor last night and then put mortar down and 1/2" generic hardibacker(the shower walls are 'real' hardibacker). over it and screwed it down. It is currently drying.

Bad idea, that. I'd recommend you un-do that while you still can. Can't prove it will cause you any problems, but it's certainly not something the manufacturer recommends.

Originally Posted by Greg

I plan on putting 1/4" hardibacker in the toilet area and under the vanity so the SLC doesn't have to fill that area too.

May or may not be a good eye-dee. Be sure that doesn't make you SLC installation thinner than recommended by the manufacturer.

There was no advantage, by the way, to installing the half-inch CBU on the floor under the heating system.

It would be helpful to know the unsupported span and spacing of your joist system in evaluating the design deflection.

And I got no eye-dee what you mean by "generic hardibacker." Either you've got Hardibacker, or you've got something else.

1. You should use the type recommended by the CBU manufacturer. I believe Hardi recommends a modified thinset. Not sure why, but they think it's a good eye-dee. Brand selection is a Ford/Chevy/Dodge issue. Use whatever brand is available to you and use a good-quality selection from that brand. Lowe's usually has Kerabond/Keralastic available. Always a good choice. The additive ain't inexpensive.

2. Mastic is an approved adhesive in that application if you wanna use it.

3. Ford/Chevy/Dodge.

4. It helps to fill the gaps between the crystals formed during hydration of the Portland cement, making the cured/dried result more dense and more elastic. The latex/other polymer material also allows it to bond better to other materials such as cured concrete and wood. It's best feature is that it raises the price of the thinset dramatically and provides a much better bottom line for the manufacturers.

It is helpful in some applications, but a whole lot of tile has been set successfully over many generations without it.

[bbcamp]

Welcome, Greg!

1) Use a latex modified thinset, either with the latex already in the mix or a un-modified with latex additive. You aren't doing anything that requires a super-duper pookie, so go with something in the $15 to $25 a bag range.

2) While it's OK to use Mastic outside the shower, why switch to something not as good and more expensive?

3) Use whatever's available, but don't use anything rapid setting. You've got enough pressure on you without that.

4) Latex makes the thinset more flexible and stickier.

[87iroc]

Thanks for the feedback guys.

May or may not be a good eye-dee. Be sure that doesn't make you SLC installation thinner than recommended by the manufacturer.

Hmmm. The Warmtiles system said that it would add about 3/16" to the height of the floor. I'll definitely buy the SLC before I put this down and see what it says. It's really not too big of a deal to me either way. Another one of those things that 'seemed like a good idea at the time'.

There was no advantage, by the way, to installing the half-inch CBU on the floor under the heating system.

I needed something to add some height to the floor. I'd never heard of the primer until last night after the board was down...I'd have considered just doing that if I had known.

It would be helpful to know the unsupported span and spacing of your joist system in evaluating the design deflection.

And I got no eye-dee what you mean by "generic hardibacker." Either you've got Hardibacker, or you've got something else.

16" on center for the 2X8s. The cross braces were wherever we felt some were needed looking at the layout of the room. There are probably 10-15 cross braces around the floor in the 'high traffic' areas.

Generic Hardibacker is just what Menards carries that isn't called Hardibacker...but has the same consistancy. I was trying to denote it from the drywall looking stuff that is used for underlayment that they carry.

1. You should use the type recommended by the CBU manufacturer. I believe Hardi recommends a modified thinset. Not sure why, but they think it's a good eye-dee. Brand selection is a Ford/Chevy/Dodge issue. Use whatever brand is available to you and use a good-quality selection from that brand. Lowe's usually has Kerabond/Keralastic available. Always a good choice. The additive ain't inexpensive.

2. Mastic is an approved adhesive in that application if you wanna use it.

4. It helps to fill the gaps between the crystals formed during hydration of the Portland cement, making the cured/dried result more dense and more elastic. The latex/other polymer material also allows it to bond better to other materials such as cured concrete and wood. It's best feature is that it raises the price of the thinset dramatically and provides a much better bottom line for the manufacturers.

It is helpful in some applications, but a whole lot of tile has been set successfully over many generations without it.

Thanks for the advice and the info!!

Oh, and I 'think' I added the first name to my profile after I made that first post.

[87iroc]

1) Use a latex modified thinset, either with the latex already in the mix or a un-modified with latex additive. You aren't doing anything that requires a super-duper pookie, so go with something in the $15 to $25 a bag range.

2) While it's OK to use Mastic outside the shower, why switch to something not as good and more expensive?

3) Use whatever's available, but don't use anything rapid setting. You've got enough pressure on you without that.

4) Latex makes the thinset more flexible and stickier.

I was just wanting to use Mastic as it would be easier to work with as oppposed to mixing mortar for all of those tiles.

I have used rapid setting stuff in the past. Definitely not something I would want to mess with with this large of a project.

Thanks for all the help guys.

[87iroc]

I thought of a couple of more questions.

Any idea of what size trowel I should use for my floor tile? They are 2X2 tile held together with a mesh or glue dot type retainer? I'm thinking 1/4 is too much, but maybe 3/16 would be OK?

Also, when putting down the SLC(I bought it, it said it is good from 0-1/2" I believe)...I think I'll need more than one bag, but less than 2.

Can I mix it up in half bag batches and get it in there or should I mix up more than enough to do the whole job and throw the extra away? Not sure if I can get 2 bags mixed before the first one starts to set and still have any appreciable work time left when I get it in there. I'll be working by myself.

Thanks,

[bbcamp]

You need a V-notch trowel for those mosaics. Something like 3/16" x 5/32" will do.

Unless you are pouring a single bag, you need a helper with SLC. Mix more than you need, and toss the excess. You won't have time to mix a batch after you find out you need it.