New to tiling, have a quick question in regards to my subfloor

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Old 12-19-14, 07:40 AM
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New to tiling, have a quick question in regards to my subfloor

Hello everyone,

I am new to tiling, well, just new to doing a whole tile project by myself.

I am about to install wood-look tile in my kitchen. Our current kitchen has sticky vinyl tile that I will remove.

Our subfloor is wood board (like 1x3 or even 5/8 x 3) and not plywood. I am in a row home and the floor is very flat and sound. Is it okay to tile above this subfloor without adding an additional layer of plywood before the tile board or ditra goes down?

I am actually interested in using ditra since it is relatively thin, but what are the pros/cons to ditra vs backer board? (I will search to see if this was discussed in a previous thread, but my main question is about the subfloor).

Thanks.
 
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Old 12-19-14, 07:43 AM
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Ditra is thinner than CBU but a little on the spendy side.

Yes, you will need plywood on top of the planks. Additionally, what's the size, spacing and unsupported span of the floor joists?
 
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Old 12-19-14, 10:34 AM
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Supersnake83,

As Mitch said, you can not install any concrete backer or membrane such as Ditra over any plank regardless whether it's a subfloor or finished floor. Examine the planks closely for slight cupping using a metal straight edge such as a square with a flashlight for back lighting. If your 3" wide boards are flat, you can get away with " underlayment grade ext. glued layers ply. If not, or if the boards were wider, you'd have to go thicker. Thicker is better anyway, so you decided.

I highly recommend Ditra but not just cuz it's only ⅛" installed.

The joists info requested is your next step. See if you can figure their species and grade too. Tell us how old the house is and its geographic location.

Jaz
 
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Old 12-19-14, 02:51 PM
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Thanks for the quick replies. I am in a row home in Philadelphia. Home built in 1925.

The floor joists are 3x8 spaced 16" on center.

Sorry, but I am not sure how to calculate unsupported span of the joists. The joists supporting the kitchen are supported by the foundation/party wall joining the next home and the other side is supported by the rear foundation wall that makes up the back of the house. Kitchen size is 11x12.

Not sure of the wood species either.

I also pulled up a section of the linoleum floor and it looks like plywood was used under the the linoleum. I asked my question and got confused because when I was in my basement and looked above the floor and saw the planks, I thought that was the subfloor because a piece of the wood that was exposed in our kitchen was the same size of the planks. However, the wood I saw in the kitchen was just an edge piece.

Pic of the joists:

Name:  floor joists from basement.jpg
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Old 12-19-14, 03:15 PM
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1/4" plywood under linoleum or vinyl is common. If that's all you have, though, above the planks it will have to come out. If you happen to have something thicker, maybe it can stay. Let us know how thick it is.
 
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Old 12-19-14, 03:47 PM
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You are correct, 1/4" of something, don't think it's plywood after closer examination.

Should I buy plywood or OSB?

Size 15/32, 19/32 or 23/32?

Thanks.

Also, should I be concerned about unsupported joist span, or that doesn't apply to this old row home?
 
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Old 12-19-14, 04:55 PM
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The unsupported span is the length of the joist between two supports. Give us the longest measurement if they vary. Since your joists are 3x you'll probably be fine. How does the floor feel?

Your underlayment thickness question was answered in #3. You'll know better what to do when the " stuff is gone.

Jaz
 
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Old 12-19-14, 05:38 PM
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How does the floor feel?
Floors feel solid. No movement or noise.

I'm confident they are 1x3s.

Give us the longest measurement if they vary
No wider than 12' from wall to wall in this spot of the house.

Your underlayment thickness question was answered in #3.
Zoomed right by it.

Thanks.
 
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Old 12-19-14, 06:33 PM
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By 12' you're talking about the supporting walls in the basement, right? 3x8 joists should give you some stiff joists. Now let's make the subfloor system and therefore the space between the joists a good base for concrete board or membrane for tiles.

What's your plan?

Jaz
 
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Old 12-19-14, 08:06 PM
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By 12' you're talking about the supporting walls in the basement, right?
Yes, this is correct.

What's your plan?
I'll go with the 1/2" plywood since the plank wood is sound and solid. I would probably use 1/8 Ditra, but if my budget gets tighter, 1/4" cement board. However, using 1/4" cement board will add to the height of my kitchen floor by a full inch above where it meets my dining room floor after the tile is installed.

I guess, no way around that unless I removed all the plank subfloor and installed plywood on the joists, then cement board, then tile.
 
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Old 12-20-14, 10:51 AM
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Be sure to ask Q's about how to install the underlayment in case you have doubts.

" CBU's work too. It's just more work and adds about 3/16" or so to the installed thickness. Plan how the tile work is gonna end at the doorways before you start. Wood, marble threshold or ?

Leave the subfloor as is, unless it's completely different from what it looks like from below. The walls are built over the subfloor.

Jaz

Note: I looked up the cost of the ply at Lowes in Philly vs. here in Troy MI and found they charge $5 more per sheet there. I didn't check HD.
 
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Old 12-20-14, 06:15 PM
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Thanks, Jaz for all of your help.

I took a closer look at what would be the floor thickness difference would be with the ply, ditra and tile installed and this would be an inch above the dining room. 1/4" cement board would make it about 1 3/8 - 1 1/4. I looked at a few thresholds and a I saw a couple quarter rounds, but they were for 3/4". I saw a rounded square threshold with .88, but I think using something like that would cause a lot of tripping. Is this type of floor difference common in a house situation like mine?

Thanks.
 
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Old 12-20-14, 07:28 PM
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I also forgot to mention we have an exterior door in the corner of our kitchen, that will be getting replaced. This now adds to the complexity of the install. It sucks for me because after seeing all the time and the sales going on right now, I really want to do the tile, but thinking I might have to switch back to the vinyl plank flooring to ease the burden of all the changes.

I'm back to the drawing board to figure out a solution to see if I can keep the plan to do the tile.
 
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Old 12-20-14, 07:51 PM
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The new door can be hung a little higher if necessary. Might need to raise the header a bit, an experienced carpenter can do it without any drywall damage at all. A wooden door can be trimmed and the threshold replaced.

An inch height difference between rooms is not uncommon and you'll get used to it quickly. If it was a public or commercial place I'd be more concerned. You can make a bevelled threshold and minimize the difference. Otherwise you can always install the same flooring in all the rooms and then it'll all be the same.

What type of finished floor is in the dining room?

Jaz
 
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Old 12-20-14, 08:05 PM
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What type of finished floor is in the dining room?
Hardwood floor throughout the house. The only two rooms (aside from the basement) that did not have hardwood was the kitchen and bathroom.

I thought about hardwood for the kitchen, but it would be very costly.

I would hang the door myself and get a steel door. I'll take a closer look tomorrow morning to see if I have any play room outside the house as our row home has brick on the upper part of the rear of the house. I'll Also check to see if any doors are readily available without special order with the height I need.

Thanks.
 
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