Advice for LARGE retail space

[chipreibel]

Greetings, all. I am in the process of opening a retail store in SoCal and want to install 18" x 18" porcelain tile (according to what I have learned, porcelain is better/stronger than ceramic).

Here is the kicker - the retail space is approx 2,200 sqft (the main retail area is about 80' x 21') and is on a raised foundation. I am unsure of the joist/subfloor thickness (will need to "find" a hole or trapdoor to investigate further). I found the "Deflecto" utility - will definitely use it as a reference.

I have laid tile before (onto concrete) but never onto a subfloor. As such, I have a few "newbie" questions (relating to the subfloor) before I go too much further. (Please keep in mind that I do not own the space, I am only leasing it for 5 years. The floor needs to hold-up but I don't need to go overboard.)

1) There is currently a laminate floor in the space (12" tiles). Can I install the cement board directly on top of the laminate?

2) I think that it would be best to stagger the cement board so that they are not in a grid pattern (picture a typical staggered subway tile installation). Does this sound right?

3) Does the cement board need to be screwed into the joists (my assumption is "yes" but I wanted to be sure)?

4) Do I need any material between the existing floor and the cement board (thinset, for an example)?

5) Do I need to tape/prepare the seams between the cement board panels prior to setting the tiles?

6) What is the recommended sub-floor thickness? For an example, if the space currently has 3/4" plywood, is this sufficient? Would I need to increase the subfloor thickness (using additional staggered layers of plywood) before laying the cement board?

7) What thickness of cement board do I need?

8) What is the most "cost-effective" version/brand of cement board? (I intentionally did not use the word, "cheap" as I am not looking to cut corners, but remember - I do not own the space.)

Thank you in advance!

[bbcamp]

Hi, Chip!

1) No. Remove the laminate and evaluate what's under it.

2) Stagger the backerboard joints so that no 4 come together at one spot.

3) No, avoid driving your fasteners into the joists.

4) Thinset. Read the backerboard installation instructions. Follow them.

5) You can tape and mud the joints as you tile. Don't forget, though. Not taping is the second leading cause of tile failures over backerboard underlayment. First being skipping the thinset under the board.

6) Most underlayment manufacturers say 5/8" plywood or OSB is sufficient. We say that you are not likely to find a 5/8" subfloor that has not been compromised in some way. 3/4" thick is OK, adding another layer is good. Just remember the minimum thickness for the second layer is 3/8", and it must be an exterior rated plywood or OSB.

7) 1/4" is for floors.

8) Normally, Versabond is what I recommend for the average homeowner's projects. Not seeing your situation, I can't say that you need something better. Let's see what you find as you start your demo.

[Trask]

In addition I would investigate Scluter Ditra..It would not only cut your labor down (at least by half) But in my opinion it will hold up far better..especially in a commercial setting.

Check your floor structure first.

[chipreibel]

Bob -
Thank you for the quick (and thorough) feedback. I will see if I can get into the space to inspect the floor joists (we have agreed on the terms of the lease and are going through the final agreement process now). The existing ply appears to be in good shape (there are about a dozen laminate tiles that are missing and give a good view of the plywood). Depending on the thickness of the existing plywood, I may go ahead and add another layer of 3/8" ply just for good measure.


Trask -
Thanks for the tip on the Schluter-DITRA product. I looked it up and watched the demo on YouTube - that stuff looks great. I just called a local distributor, and it goes for $1.69/sqft... As interesting as it is, it's a bit out of my price range - I'll probably need stick with the cement board (which is around half the cost).

Thanks guys!

[Kman]

Chip, I'll bet you can find Ditra cheaper than $1.69 a foot. You can get it at www.tile-experts.com for about $1.32 a foot, maybe even less if you tell them you need seven rolls, and they'll Fed-Ex it right to your door.

Ditra can save you time, money, and work in several ways:

1. You won't have to buy or drive any screws or nails
2. You won't have to tape and mud the seams
3. Your total weight for underlayment will be less than 300 lbs. for Ditra vs. 3000 lbs. for a standard tile backer.
4. You can cut Ditra with a utility knife as opposed to a grinder or scoring tool for CBU.
5. You'll have less waste.
6. The installation for Ditra is much faster than CBU
7. Ditra is a far better uncoupler for tile

About a year ago I quit using CBU on floors altogether in favor of Ditra. Haven't had a single problem with it. There are a lot of installers on this forum that use it and are ready to give you any advice you need to install it.

[Trask]

I totally agree with Kevin on the Ditra. Chip I dunno if you've ever put down 2000sf of backerboard..But it is a hard, dirty and time consuming task. I wouldnt do anything but Ditra just for that reason alone. Also with Ditra and porcelain you may be able to eliminate the extra layer of ply..that would save some $$$ and time too.

Just thought I'd chime in again because the thought of heaving all that backerboard around gives me flashbacks

[chipreibel]

If I can use the Ditra product directly on top of the existing floor (and eliminate the need for an add'l layer of plywood and a layer of backer board). I am absolutely SOLD. I will check out the existing floor this weekend and report back.

When using Ditra, should I still reference the "Deflecto" utility, or does that go out the window (with my ply and backer).

Thank you SO much, guys - I can't tell you how much I appreciate your help and advice. Needless to say, I wasn't excited about laying 2,200sf of ply, 2,200sf of backer and then 2,200sf of tile...

[Trask]

Chip here's a link to the Ditra Install Handbook http://www.schluter.com/media/brochu...k-2008-ENG.pdf

I would still check your joist spacing/span ect.