1/4" to match adjoining rooms

I have to build up existing 3/4" particleboard underlayment 1/4" so that the engineered hardwood I'm about to put down will be even with adjoining rooms. I'm thinking 1/4" plywood, but do I need to glue/screw, or just screw? If I use 2" screws, I'll get to the subfloor and it should anchor well.

The room is about 12x14, and I also wonder whether 1/4" Hardibacker will make for a more solid installation, even tho I'm not putting down tile. I could glue/screw, but if I would have to use thinset, I'd stick to the plywood.

Thanks for your thoughts.

Lenny

 

Are you sure it's particle board and not OSB? Huge difference.
I would not any type of flooring over particle board.
Under layment is never glued or screwed down, it would leave humps in the floor.
You use under layment nails or better and faster to use a narrow crown pneumatic staple gun.
It's attached every 4" on the edges and 6 to 8" in the field, and never attached to the joist.
Hardibacker would be a waste of time and money.

 

Are you sure it is particleboard and not OSB? If particleboard, it may be 5/8" thick and not 3/4". But the best move is to remove particleboard if that is what it is and replace with 3/4" advantech or equivilent.

Then if you put down 1/4" underlayment grade plywood (not luan) then you use ring shank nails or crown staples. Every 2 - 3 inches perimeter and ever 5 - 6 inches in the field.

Hardiebacker does not add anything structural to the floor and is usually set in a bed of thinset mortar to help support it.

 

Here's what the logo on the underlayment says, I've used OSB before, and the particles on this stuff are much smaller. It may be 5/8", but I can't really get to an edge to measure precisely.

Lenny

 

Yes, that is particleboard, and the weak link in your whole flooring setup. Any, and I mean any, water gets to this and it is toast. You jeopardize your whole flooring installation. Best to replace now and ensure a lasting installation.

You also can not nail down flooring to particle board as it does not have the grip power to hold the fasteners. It "blows out" rather than holds tight. Of course, we never mentioned how you are putting down your engineered floor.

 

The good thing is it is probably 5/8" and you will be replacing it with 3/4" giving you almost the height you need. Adding a thin layer is not a good idea for anything much more than linoleum.

 

It's locking/Floating system, I don't recall the manufacturer right now. My plan was to use fasteners that are at least 2" long so it would grip into something other than the particle board. I have a 2"+ pneumatic narrow crown stapler, but I had planned on using long drywall screws that would sit flush under the padding layer of the floating floor system. It would add a huge amount of work to tear out and replace the board that is there. What if I sealed it up, using the latex primer designed to go under self-leveling concrete? I suppose that might help, but not against a large amount of water.
I should note that most of my first floor is tiled, on top of 1/4" Hardibacker, which I assume is thinset to the particleboard below.

 

Why are you stapling/nailing a click lock floor? Lotta work, with little return, IMO.

 

not the floor, the floor will float, I was talking about adding a 1/4" layer underneath

 

If you've got tile on particle board, you are a ticking time bomb just waiting for a failure.

Yes it is, and probably why people choose to hire stuff like this out. However, we are here to advise on proper procedures. We can't force you to do anything. But we here believe that the inventor of particleboard should have been taken out behind the barn long ago and taught a lesson for all the grief he has caused. We can't change what you have currently, it is what it is. You, however, can change it and make it right for your current investment.

BTW- Drywall screws are about the worse item to use for flooring. The are not designed for that and the heads snap off. Use exterior deck screws when you decide to replace your subfloor.

 

So just so I am sure of what's going on - I have a plywood subfloor, then particleboard underlayment, so the advice is to tear out the particleboard and replace with plywood, OSB? or advantech.
Correct?

 

Yes. You will find that if the particle board is bound under cabinets, etc. it will snap if lifted sharply, so you may not have to cut much of it. Clean up the edges and lay down the Advantech.

 

Nope, room is wide open, so it's just a matter of actually doing it.

Thanks everybody for all your help.

Lenny