What are the proper terms for subfloor components?

[Tidybuoy]

I seem to have to explain over & over what I'm working on and I really don't know the proper term for this.

Kitchen floor has 3 layers (on top of joists).
1) 1x6 floorboards/planks
2) Plywood sub-floor
3) Tile

What are the proper terms for 1 & 2. I tell someone I finished the sub-floor but now I need to do the sub-floor?? Or, are 1 & 2 simply "components" of a sub-floor?

[A930Rocket]

You must have an older house or a really nice house. For the last 40 years, most houses use (1) floor joists, (2) 3/4”+ decking of some kind such as plywood/OSB/etc. and (3) the finished floor such as tile/wood/carpet.

[Gogar]

Originally Posted by A930Rocket

You must have an older house or a really nice house. For the last 40 years, most houses use (1) floor joists, (2) 3/4”+ decking of some kind such as plywood/OSB/etc. and (3) the finished floor such as tile/wood/carpet.

Your floor probably has has a OSB or plywood sub-floor laid on top of the old plank sub-floor

My 1928 home has the original 1x6" sub-floor and 2.25" red oak laid right on top of that for squeak-tastic fun all day long!

[masraum]

Originally Posted by A930Rocket

You must have an older house or a really nice house. For the last 40 years, most houses use (1) floor joists, (2) 3/4”+ decking of some kind such as plywood/OSB/etc. and (3) the finished floor such as tile/wood/carpet.

Yep, his home is old, I think 100+ years.

[gregpark]

The 1x6 boards on the joists is your subfloor.
The thin plywood on top to smooth things out is called underlayment

[cabmandone]

What Greg said.

[look 171]

Plywood was installed, not original to house, for the tile and there's normally something else like Wonderboard or some type of top of plywood for the tile for structural integrate. In some instances, tile was installed directed on top of this plywood.

[Bill Douglas]

Just for fun some other terms. The bits that run the other way holding up the floor joists are called bearers. And piles or foundations are the vertical supports that hold the bearers up.

[Tidybuoy]

Originally Posted by gregpark

The 1x6 boards on the joists is your subfloor.
The thin plywood on top to smooth things out is called underlayment

Perfect!

Yes, my house is old. The floor started with 1x6 subfloor, then 3/4" hardwood floors, then 1" Saltillo tiles. The tile was removed as it was really old and worn. I removed the hardwood flooring because it had some damage & unsightly repairs, then I removed some of the 1x6 subfloor that had some rot. I replaced with new 1x6 subfloor, now installing 3/4" plywood. Lastly (after cabinets are installed) I will be installing 12x12 Saltillo Tiles (trying to keep the Spanish theme). This is for the kitchen and laundry room only.

Thanks for all the advice.

[gregpark]

Bill, we call those posts and beams in the upper right corner of the world but I'd know what you're talking about 😃

[Tidybuoy]

Originally Posted by look 171

Plywood was installed, not original to house, for the tile and there's normally something else like Wonderboard or some type of top of plywood for the tile for structural integrate. In some instances, tile was installed directed on top of this plywood.

My house had 3/4" oak hardwood on top of the subfloor. I am the one installing 3/4" plywood in place of the hardwood floor as it was heavily damaged over the years and has several repairs.

On top of the plywood, I will be installing Schulter Ditra Uncoupling Underlayment. This helps to keep tile from cracking, due to any floor movement. I won't have much movement as I screwed down the floor tight vs. original nails.

[Tidybuoy]

Originally Posted by masraum

Yep, his home is old, I think 100+ years.

Built in 1929, Spanish style home.

[Bill Douglas]

Originally Posted by gregpark

Bill, we call those posts and beams in the upper right corner of the world but I'd know what you're talking about 😃

Thanks. I think those names are good. I may use them myself to sound more, umm, international.

[look 171]

Originally Posted by Bill Douglas

Thanks. I think those names are good. I may use them myself to sound more, umm, international.

International that does not include us.

I have not heard of that term used before nor they in any books. Interesting. Learn something new daily here.

[look 171]

Originally Posted by Tidybuoy

My house had 3/4" oak hardwood on top of the subfloor. I am the one installing 3/4" plywood in place of the hardwood floor as it was heavily damaged over the years and has several repairs.

On top of the plywood, I will be installing Schulter Ditra Uncoupling Underlayment. This helps to keep tile from cracking, due to any floor movement. I won't have much movement as I screwed down the floor tight vs. original nails.

This is what we do to stiff up floors.

Remove all the 1x6 sub floor in that area or room glue, nail, or screw 3/4" plywood for a really stiff floor. If you go that far, I suggest installing a girder on a couple piers for additional support to keep bounce away. We normally use a 4x6 depending on the span. Its better then any crack isolating materials. Still install Ditra on top to keep cracks away. Oh don't forget to block off the joist. Once you have it opened up, all that should take half to a day to do. If you are concern about the unevenness between Mexican tile and existing hardwood flooring, then go 5/8" sub floor or plywood. If the room is big, don't forget to stagger them for added strength. Blocking off them keeps the joist nice ad straight too. Not too much money or work but IMO, the gain is worth it. This is not normally done with normal, standard construction.

[look 171]

Originally Posted by Tidybuoy

Built in 1929, Spanish style home.

I know all about them. Torn apart many of them over the years. My parents has one, 1929 also. That whole house is remodeled. All the old stuff gone but kept some of the old details or I replicated old damaged ones myself.

[Zeke]

Originally Posted by Bill Douglas

Just for fun some other terms. The bits that run the other way holding up the floor joists are called bearers. And piles or foundations are the vertical supports that hold the bearers up.

"Bearers" works for me. I've never heard it that way either, but we all know what a bearing wall is and a load bearing beam. Beam is the US word, but I'd understand you right off.

We also call them "girders" if they carry more like down the center of a floor system where floor joists are broken.



@gragpark is certainly right as he is the floorman here, but I sometimes think of underlayment as a lighter material. Lot's of 1/4" ply has been used over old floors. A full 3/4" ply layer can be subfloor laid over diagonal sheathing to me. It becomes structural nailed through to the joints. I've done that a lot. Then the cement board which is truly underlayment. It's all relative.

[gregpark]

Anything between the floor covering and the subfloor we call underlayment.

I always considered a girder as one central larger beam supporting lesser beams which support the joists? Just semantics? who cares? everyone knows what you're talking about when you mention beam or girder

[Zeke]

Originally Posted by gregpark

Anything between the floor covering and the subfloor we call underlayment.

I always considered a girder as one central larger beam supporting lesser beams which support the joists? Just semantics? who cares? everyone knows what you're talking about when you mention beam or girder

Yes on the girder. A 2nd layer of support would always be a girder. But break the floor joists over a beam and the semantics do get in the way. The only place my floor joists break are over a stem wall with cripple studs (built 1930).

[Bill Douglas]

Good terminology thanks, I'm learning things.

Here in NZ a girder usually means a RSJ (rolled steel joist) in I profile and is used to span quite a width. Then (usually) bearers and joists. I did a reno' job where I didn't have much room under the floor so ran a steel I beam/girder, then sat the joists on top of that. It worked well.