Brian & Jean’s Kitchen, ½ bath, and laundry Project

[bjseibel]

Hello, I’m a newbie to the forum and this will be my first tiling job. I have been lurking and surfing trying to learn as much as I can so I need to begin a thread with some of the basics about my project.

Existing floor:

Joists: 16” o.c., 2”x10” Douglas fir, maximum span of 13’ 6”
Subfloor: 15/32” OSB glued and screwed to the joists
Underlayment: 5/8” Plywood screwed down but I’m not sure if it’s screwed to the joists and whether it’s interior or exterior.

Flooring: Vinyl without cushioned backing. Glued down throughout, Armstrong inlaid vinyl.
Age of home, vinyl, subflooring: 16 years
Adjoining areas: Carpet and ¾” oak hardwood foyer floor
Total square footage: approx. 400 sq-ft.

Planned floor:

Tile and Pattern: Porcelain tile. Not sure but investigating hopscotch with 6”x6” tile and either 18”x18” or 12”x 12”. Also considering diagonal under table with “plain” straight layout else where.

Considering Radiant heat system.

Maximum length of tile field: Approximately 30’ when hallway is included to laundry.

Decoupling system: Ditra


Questions:

1. Is my subfloor and underlayment o.k.? I believe I have a L factor greater than 360. My concern is if the 15/32 OSB is o.k. and that the plywood underlayment is exterior grade without voids/knots.

I was originally going to tile over the vinyl because it appeared that it was tight to the floor. However, after removing a couple of floor heat vents/returns, I could place my hand between the vinyl and underlayment for a few inches. It seems as though the vinyl mastic is “dried out”. So, I either have to strip the vinyl or get a toe kick saw and remove the underlayment with the vinyl on it.

2. Is there a chance that the vinyl is tight in the walking areas and that it is only loose around the vents? Does anybody have any experience with old vinyl and how it typically “loosens up"?

2. If I tear out enough vinyl, will I be able to tell if the underlayment is exterior or interior. Should there be a stamp on it identifying the grade/type?

3. Removal of the OSB would kill the project. My wife would never go for that much demolition. If I have to remove the plywood subfloor, would replacing it with 5/8” plywood of the correct grade be o.k. with the 15/32” OSB or would I have to go to ¾” plywood?

4. If I replace the underlayment plywood, is the 15/32” OSB thick enough to hold screws between joists so I can follow good underlayment installation procedures or will I have to screw to the joists through the underlayment and subfloor?

5. With the length of the tile field approx 30', should I place an expansion joint in the hallway between the kitchen area and the laundry/powder room area? It would be around 21' from the opposite end of the kitchen to the joint. The kitchen area is approximately 11'6" wide.

Thanks in advance for your help
Brian

[Marge]

Brian and Jean, welcome to the forum.

We'll get some folks over here to help you with those questions...hang tight.

[cx]

Welcome, Brian.

1. Well, your subfloor doesn't really even exist as far as some of us are concerned. I'm always amazed that anyone calling hisownself a builder would lay half-inch plywood over joists for a floor of any kind. And I think this is the first time I've ever heard of starting with half-inch OSB. It's criminal, is what it is.

Does yours actually say it's 15/32nds? Some of the manufacturers are starting to be a little more honest and marking their beaver barf as 7/16ths.

In any case, if that's what you have, and your domestic relations won't tolerate removal, we'll pretend it's just fine. Actually, we'll be even more honest than that and pretend it ain't even there.

Your plywood underlayment we can only guess at. How did you determine that it's 5/8ths thick? It's pretty unusual to see plywood that thick used to install vinyl, but over that thin OSB, well........who knows what the thinking was.

2. It's possible, but I still don't like to see people try to tile over that stuff.

Other 2. There will be grade stamps on the plywood. Whether you'll locate one on the side you can see or if it'll be readable is anybody's guess.

3. I would not recommend anything less than 3/4" plywood over what you have, and I would treat it as a single-layer installation, screwing it directly to the joists. It would need to be T&G to make me happy.

4. See 3.

5. I would certainly recommend you put in the movement joint. At 21 feet you're within industry standards unless your floor will get a lot of sunlight exposure or moisture.

My opinion; worth price charged.

[bjseibel]

Thanks Marge for the help!

Cx,
I was afraid you were going to say the OSB is garbage! I have learned over the years that a project is only as good as it's prep work and that the floor structure is the most important for this one.

The OSbarf is marked on the basement side and I can actually read the stamp and it is marked 15/32". I know the plywood is 5/8" because I pulled up a through floor heat vent and I measured it. So, it looks like if I do this, I'll be putting down T&G 3/4" after ripping out the 5/8" with vinyl. The good news is I don't have to scrape vinyl and mastic...only go screw hunting

Do you know where I can get that plastic sheet stuff to "wall" off the rest of the house from the dust mess I'm about to create? I would think most big box stores carry it.

Thanks
Brian

[cx]

I'm actually one of the few supporters of OSB hereabouts, Brian. I have no problem with the product at all so long as it's of good quality and used correctly. I, in fact, will not use anything else as roof decking and have not for twenty-odd years now.

Others, non-believers, persons of little faith, lesser beings who fear change, taught me to call it beaver barf.

Had you some nominal half-inch plywood as that first layer my opinion would be exactly the same. 'Specially since neither is T&G and I can bet heavily without looking that the seams are not blocked. It's the method, not the material that's in question here.

You should be able to get lotsa poly sheeting at Homer's for your masking purposes. Comes in a wide range of thicknesses (0.75mil to 6mil) and sizes (9x12 to 20x100 feet) for your every need.

My opinion; worth price charged.

[bjseibel]

Cx,
Thanks!!! I need to check if Homers has a toe-kick saw for rent anyway so I'll look into the plastic. I still have to convince my other/better half about doing tiling because of the effort required. She is facing some medical issues right now and I told her that if/when I do this it would be better if she were at Grandma's for a while. I'll keep you posted on here when I actually make some progress. It will be slow to say the least. Hunting season is upon us and I have promised two of my kids some days in the woods

Brian

[bjseibel]

I've given my subfloor issue some more thought and I've realized how much higher my tile floor will end up being than my hardwood foyer floor(15/32" + 3/4" T&G oak) if I don't rip out that 15/32 OSB. I have another list of questions.

1. If I tear out the subfloor what is the easiest way to remove glued and screwed OSB from my floor joists and contain the mess in the basement (putting poly below the joists) ?

2. How do I remove the glue(I think it's pl400) from the joists so I have as close to an even/level floor as possible?

3. If I do this, would 3/4" T&G plywood be the recommended subfloor with a radiant heat mat/wire attached to the plywood, followed by thinset, more thinset, ditra, more thinset, and then porcelain tile?

4. Is there a reference or liberry posting that lists the nominal thickness of each of those layers? (I recall 1/8" for ditra and 1/8" for a heat system but what about nominal thinset thicknesses?)

Thanks!

[cx]

1. Good luck. Ain't no easiest way.

2. See #1. I'd use a 2" wood chisel and whine alla while.

3. You could do that so long as the heating system people agree.

4. Don't think so. Both the Ditra and heating mat are gonna be thincker than that installed, more like 3/16ths" or so. Minimum thickness for thinset under a tile installation is 3/32nds". Your milage may vary.

My opinion; worth price charged.

[bjseibel]

I'm hoping to revive this project and have been considering removal of my whole subfloor and replace it with the T&G plywood. I have looked at Stud-I-Floor at Home Depot for ~$20/sheet.

1. What is the best/fastest way to remove the subfloor down to the joists? i.e. sawzall? I have to cut around kitchen cabinets...toe kick saw? Chisel?

2. I have an island in my kitchen that I can either cut around or remove it temporarily to allow subfloor removal and tile under it. It would end up 1/2" higher than other cabinets. What would you do?

2. What is the best 3/4" T&G plywood to use as a single floor subfloor? Sturd-I-Floor?

3. Do I block all edges of the plywood and ends that don't land on a joist using 2x6, 2x4, or 2x10(joist depth)?

4. Should I glue and screw the plywood to joists and blocking?

5. If I should glue and screw, please recommend a glue and screw type, length, and size.

6. Should I not glue T&G edges together before spacing them 1/8" ?

Thanks