Lets talk subfloor/underlayment.

70 year old house, C neighborhood. Lowest layer is 1x 6 on the diagonal. I’m replacing the craptastic crumbled layer of particleboard which supposedly made the second layer of subfloor that was basically held in place by the nine layers of various flooring above, rather than through any structural integrity.

Oriented Strand Board (OSB) is going down.

So, here are my knowledge deficits:

1.Staggering seams. I know NOT to have any seams meet with four corners together. But, is there any reason that I shouldn’t put one 73 x 21” piece under where kitchen cabinets go, perpendicular to the the two full four by eight sheets? The two 4x8’ sheets will then begin 3” under the cabinets, and run to the opposite wall. Or, should I stagger all the sheets, leaving a seam under the kitchen table, 21” inches from the wall?

2. Narrow strip. The kitchen (and its supporting joists) is 12’ 9” . Thus, three sheets of OSB leaves a nine inch strip. Any reason the nine inch strip should NOT be adjacent to the wall adjoining the living room, and thus adjacent to the doorway between living room and kitchen? Kitchen is a galley kitchen, so that nine inch strip is perpendicular to the main traffic pattern. It will either be next to the wall, or four feet in.

3. Screws, yes? ( not nails or crowned staples) I’m pretty sure on this one. I’m not planning on doing underlayment, just doing loose-lay sheet vinyl that will get replaced with each turnover. To prevent those pop-up chips around screw heads from telescoping, I’ll run the random orbit sander after finishing the screws. (Not worried about OSB pattern telescoping. If it does, oh well!)

4. Spacing of screws. About 6 inches around edge of each sheet, 12 inches in the field? And DO NOT screw into joists, yes?

5. Overthinking? Yeah, probably. The grandkids are getting at an age where I can occasionally use them for labor, and Grandma wants to teach them well.

Thanks y’all! You are the best!

1. I think either would be fine.

2. I would try to avoid such a narrow strip, by cutting a full sheet a little smaller. I would put the narrower piece (no less than 12-16") away from the wall.

3. Definitely screws - construction screws. The screws will make some sharp point poke upward, so good idea to sand - especially with easily-torn sheet vinyl. Of course, make sure the screws are in nice & straight so you don't have the edge of the screwed poking through the floor either. For less telescoping, you might consider smearing a bit of wood filler over the screw heads.

4.Yes, 6 & 12 (ish)Try to screw into every joist you can for added strength.

5. Yes, put those kids to work!

Thank you both! Plenty for the encouragement and DJ for the advice. Hadn’t thought of reducing the four foot width on one sheet to increase the nine inch strip. That makes perfect sense!

Oh, you know OSB has the rough side & the smooth, glue side. you might want to put the smooth side up, even though that is not the "standard" installation for subfloor.

I hope you aren't planning to use 1/2" OSB - like I mistakenly did previously.

Instead of OSB, go with 3/4 Advantech on the bottom layer and 1/2" plywood for the top layer. Bottom layer is screwed to the joists and top layer is not. Advantech also has markings on where to fasten it. If I was doing it, I'd replace the pine boards altogether.

If you have a framing nailer, which I am sure you do, then shoot 8d ring shank nails instead of running screws.

Once you shoot a sheet down run your hammer over all the nails to be sure they are set deep enough.

Loose lay with no glue should not telegraph the OSB.

Personally I stopped using loose lay because it would bunch up when someone moved say a stove or a fridge. Sometimes even a kitchen chair would start it.

If you really love the sheet vinyl maybe look into a releasable glue. I did that for a long while. I was even able to fix some tenant caused gouges and small tears with a roller and a heat gun.

DJ, yup, I noticed the shiny side and the fuzzy side, and I'm checking before I cut. Also, 19/32", which will match up nicely with living room hardwood.

Roy, yup, ended up replacing three 1 x 6 s. One thing I learned- replace a longer length than is damaged. Once the one by is cut shorter and patched in, it gets bouncier. Originally I was going to do tongue and groove plywood, but hubby and I were researching, and for some reason we changed our minds to OSB. It wasn't price, because I won't go cheaper when it comes to structure, unless cheaper happens to be better. How it was better, I cannot recall. Made that choice waaay back in Novemer, then tore the bathroom apart and forgot about the kitchen, lol!

6 x 6, and Zero, my husband has a framing nailer, BUT, I don't like using it. I end up asking my husband for advice, which leads to him wanting to get involved. And in our relationship, that is not good. If I was absolutely certain nailing was better, I'd suck it up and get out the framing nailer. 6 x6, and anyone else trying to remove old screws here's the trick for removal- TIGHTEN the screw ever so slightly to break surface tension, THEN back the screws out. Only needs to go forward a tad, and it will back out. I had fun with that trick. My husband wanted to help me remove some of the many old screws and nails in one of my basements. He deemed a dozen or so screws impossible to remove, wanted to cut them off. I just set the drill to forward, and went slow, then fairly easily backed them out. ( and yet my husband still thinks he's smarter than me, lol! Ok, maybe he is, but I got that one!)

Oops, didn't mean to leave you out, Jason. Yep, I did run the 8 foot length perpendicular to the joists. Except was thinking of running it parallel for that bit under the sink cabinets. My husband said I should stick with perpendicular for the entirety. See, maybe he is smarter! I'll do perpendicular for the entirety.

If this for one of my places I would do the following.

1. remove all of the old junk "fall-a-particle board"

2. refasten the diagonal subfloor

3. install either 3/4" Advantec or 5/8" Zip roof with screws into the floor joists. Unlike regular wafer board both of these hold up really well to moisture

4. use seam filler on the joints

5. install LVP flooring instead of loose laid sheet goods

You're correct in using a 6" on the edges & 12" in the field screw pattern.

As long as the pieces under the cabinet base make the seam behind the toe kick & under the cabinets, you'll be fine.

If you've refastened the diagonal flooring, you can get away with not screwing the new underlayment into the joist, but I wouldn't do it this way.

The double sided tape never lasted for me on the few times I tried it. I still remember loose laying a kitchen. All looked fine-ish until the furnace kicked on and the floor rose up like a parachute in elementary school gym class. I didn't attach the floor around the heat vent.

You can use the releasable glue just in the high traffic areas, but I just did the entire floor. Made it less likely there would be a bubble. Plus minor repairs are easier.

Do this, it saved me a lot of time and hassle. Grab a 2x4, maybe a couple foot long. Wrap it in carpet, not 70's shag. Nail or staple it at the seam, or you can glue it instead.

Now use that to help smooth out the sheet vinyl. Loose lay or glue it works and makes life a little better. You can get (rent) a 100 lb roller to work the vinyl into the glue. I never did. I just used the board and my fat self. A small J roller helps in tight areas, same with a thin board and a hammer.

I did buy a big roller for a project with LVP where the seams didn't click as well as I wanted. I have used it a couple times but it is a pain to get to the project and going upstairs adds to my heavy breathing.

Also, practice with the framing nailer. If it is too bulky look into getting the smaller version that Paslode makes. Doesn't hold as many nails but is easier to wield.

Trust me on this, once you are over the stigma of using the nail gun it will be so much faster and easier. Small jobs, maybe screws, but a complete floor it is worth the hassle of getting the gun and compressor out. Once you get comfortable with it you can select bump shooting. That works great. Just be sure you are comfy with it as you can get yourself into trouble otherwise.

Steve- "fall-a-particle board" made me laugh. Yup, you know when the tool used to remove it was the shop vac and not the pry bar, there was no structural integrity left. I did replace some nails that were popping with screws in the 1 x 6 first layer, probably could do a few more. I'm going to have to keep the names Advantec and Zip Roof on file for the one remaining kitchen floor I do. Sounds like better products than just OSB. As for the sheet vinyl vs. LVP, I've done the planks, not completely a fan. Guess I'm going to try sheet goods this time, can always go back to LVP at next turnover. The living room, hall, bedrooms are maple flooring, which were hiding under basic carpet and peel -stick vinyl tiles, and I'll be refinishing. Most LVP is wood-look, and I want stone-look to complement the maple floors. I'm such a girl! I want pretty! I should be able to do kitchen and bath flooring change-overs fairly quickly with sheet vinyl, and the two problems I encountered with the vinyl planks I used aren't easily fixed.

Zero! I DO have a heavy roller! It is at my daughter's from when they redid their bathroom. She doesn't always return things, but I'm sure it is there. My one concern on the releasable glue would be does it attract and hold crumbs, dust, either during the tenancy, or when I pull it up to replace it. Might just have to try it and see.

Robin, that’s a good idea too. Kids would have fun snapping chalk lines too!

Robin, that’s a good idea too. Kids would have fun snapping chalk lines too!

If your grandkids are eating while standing on the glue it could get crumbs in it. Otherwise it will be completely covered by the vinyl.

Another quality about the releasable is that you do not have to lay it right then. You need to let it sit for a bit. I have had it sit overnight no worries.

When you pull the entire sheet up plan on putting more adhesive down. Most of it will be left on the old vinyl because you don't want that to happen. But much less fuss than standard vinyl glue for removal. There will be boogers as well. With the roller those shouldn't be an issue. The big ones are easily pulled away.

Those zip panels are so expensive.

Almost seems like overkill for a bathroom and especially a kitchen.

I guess buy once, cry once tho.