Moisture barrier between OSB and engineered hardwood?

[Camasonian]

Hello all. I’m planning to install a 1/2” Kahrs click-lock floating engineered hardwood floor over OSB. I plan to use 1/4” cork underlayment as a sound deadened and to raise the level of this floor to match the tiled floor it will tie into in the hallway and kitchen. This is a ground floor installation, about 3/4 of which will be over a daylight basement that is finished/heated etc. And about 1/4 of the floor will be over unheated full-height crawl space that has about 8-10ft of clearance in the crawl space. In both instances the OSB subfloor is over regular floor joists, not concrete.

I have seen mixed messages regarding moisture barriers. Some material I have read says install a moisture barrier over any unheated crawl space. Others say don’t install moisture barrier between two wood surfaces as that will potentially generate mold.

I was thinking of putting down 6 mil plastic under the cork but don’t know if that is necessary or advised. And if so, what is the best way to put down the plastic. I was thinking of tacking it down in the corners with staples and Then covering the staples with duct tape to re-seal. So that it doesn’t shift around when I roll out the cork. But I’ve never done this.

What is the consensus here in this situation?

FYI…I’m replacing old carpet with the engineered hardwood. The house and subfloor is 17 years old and looks clean and dry with no sign of moisture, etc. under the old carpet pad.

 

[Mark Brown]

Use a vapor retarded. Unlike poly it will allow some moisture to move.

Look at aquabar B, that is what i would do

 

[Camasonian]

That looks like a good intermediate solution. One Kahrs spec sheet says to use 6 mil plastic under the underlayment and wrap it up 2” on all sides. Another says it isn’t needed over wood subfloors, only over concrete. So even their advice is inconsistent depending on what you read.

Aquabar B is available for about $35 for a 500 sf roll at my local HD so pretty cheap and easy solution. I think that is what I’ll do.

 

[Mark Brown]

its a very good in between.
plastic on wood doesn't really worry me seeing as we glue sheet vinyl to wood all the time, but I dont really like the thought of the unknown

 

[Camasonian]

Well, I went with the Aquabar B and used the red underlayment tape to tape it all down using the 4” overlap which I assumed was intended by the marking lines on the sides of the roll that were 4” from the edge.

On top of that I put down 1/4” cork which, combined with the 1/2” thickness of the engineered hardwood gives me the perfect elevation to match the adjacent tile floors that are 3/4” thick. The tile is actually maybe 1/16 or 1/32nd thicker than 3/4” which is better still because if I create a seamless transition without molding then it will be the tile edge rather than the wood edge that is sightly proud. I assume that is better because the tile is much sturdier and less prone to chipping and splintering than a slight wood edge would be.

My idea which I picked up on another site is to lay a 1/4” foam rod as a spacer between the tile and engineered hardwood and then use flexible tinted caulk over the top to create a grout-like appearance. I figure if it ends up coming apart and looking bad over time I can always go back with a circular saw and trim off the edges of the wood planks in place to create a wider gap between the hardwood and tile and then drop a t-molding over the top.

 

[Mark Brown]

I dont know what you are doing here because by the sounds of it you got this thing all dialed in

Solid plan and I wouldn't add a damn thing. Well played! Best of luck too... it NEVER hurts to have a boat load of luck at hand.

 

[Camasonian]

So far so good.

I’m using Kahrs Oak Tapa engineered hardwood which has a sophisticated tongue and groove locking system that they call Woodloc 5G. You insert the long edge of the next board into the groove, press down and the ends snap-lock into place. Then use a tapping block to make sure all the seams are tight. It is going together extremely easily and quickly and the product seems well engineered as the tolerances and seams are all coming out perfect. We shall see how it wears. The only hassle is the corners where I need to insert it under the under-cut door jams. On some of those I have to chisel off the edge of the tongue and glue it because I can’t insert at an angle and snap down when it needs to slide under the door trim.

But it is MUCH MUCH easier and nicer than the last floating floor I did a decade ago, which was Wilsonart Laminate that I had to glue together and use long webbing clamps to cinch up.

We shall see how it all ends up but going with the 1/4” cork underlayment was a MUCH easier and cheaper solution than putting down a thin sheet of plywood and thin sheet of underlayment to gain the equivalent elevation.

 

[Mark Brown]

That 5g system is the cats meow and will provide you with a lifetime of happy feet. Well chosen and solid plan.

 

[DarisMulkin]

Pictures of the finished or even 1/2 finished product is always good.

 

[C.J.]

Just me but I’d cheat the gap between the wood and tile down to 1/8” for a cleaner look. I might even bump the tile with the wood if I knew the full layout and felt comfortable doing that.

 

[Mark Brown]

I would do it regardless but I am open to risk

 

[C.J.]

I would do it regardless but I am open to risk

I’m open to calculated risk. Giggity. I gotta know what the heck she looks like before I ask her out.

 

[Camasonian]

What do you guys think about using the Schluter Reno-T metal transition strip between tile and engineered hardwood? It looks to be lower profile than the thick hardwood T-moldings that the flooring companies sell, and also cheaper. I figure I can probably try just caulking the joint with some sort of tinted silicone caulk that matches the existing grout and if that doesn’t look good or fails, dig it out and put in something like this instead. Opinions?https://www.schluter.com/schluter-u...itions/Schluter®-RENO-T/p/RENO_T?facets=false

 

[Mark Brown]

What do you guys think about using the Schluter Reno-T metal transition strip between tile and engineered hardwood? It looks to be lower profile than the thick hardwood T-moldings that the flooring companies sell, and also cheaper. I figure I can probably try just caulking the joint with some sort of tinted silicone caulk that matches the existing grout and if that doesn’t look good or fails, dig it out and put in something like this instead. Opinions?https://www.schluter.com/schluter-u...itions/Schluter®-RENO-T/p/RENO_T?facets=false

I use them all the time because they are sexy as sin and like you say, a much lower profile. Soldier on!

 

[Camasonian]

I use them all the time because they are sexy as sin and like you say, a much lower profile. Soldier on!

Do you use any special brand of glue to glue them in place? Or just ordinary construction adhesive like liquid nails?

 

[Mark Brown]

I typically use a 100% silicone because it sticks to just about anything and stays flexible enough that I pray it will reduce things like pressure fractures. Haven't been called back for any of them so I can only assume the track record is good. Rarely do I see past work I have done.

 

[highup]

I typically use a 100% silicone because it sticks to just about anything and stays flexible enough that I pray it will reduce things like pressure fractures. Haven't been called back for any of them so I can only assume the track record is good. Rarely do I see past work I have done.

You're only supposed to see past work when you're back doing present work.