Luan over an old plank subfloor for Coretec Plus?

[lucitedragon]

Hi, all. I'm a homeowner about to install Coretec Plus and, pulling out the old, beat up hardwood I found I had an old plank subfloor instead of plywood. The planks are in pretty good condition and mostly level, but there are some areas where planks are lower or higher than others, and a few spots where a plank is loose. To be safe should I just put a layer of Luan over the plank subfloor and then put the Coretec on top of that or is that an extra step and expense that I don't need to worry about? Is a plank floor in generally good shape alright to have Coretec installed directly on top of it? Thanks in advance for your help.

Sincerely,

Jason Bloom

 

[Floorist]

Luan is not acceptable under any flooring. It tends to have voids between the plys which can collapse. It also can stain. I wouldn't put any vinyl plank directly on the old plank floor either. At the least, I would use an underlayment grade 1/4" plywood subfloor. If it were mine, I would probably put at least 1/2" plywood over the planks.

 

[lucitedragon]

Thanks for your reply, Floorist. I only mentioned Luan specifically because a friend who almost had LVT installed and had a similar plank subfloor was told by his installer that he wouldn't put in the flooring without first adding a layer of Luan. But what you've said makes sense. My only fear with putting in 1/2" plywood over the planks and then the LVT is that the threshold into the kitchen might look a little silly with such a big step down. If I put in 1/4" plywood will I be unhappy with the final installed results? Should I maybe step up to 3/8" plywood as a happy median?

 

[Floorist]

If the plank floor is fairly smooth, you probably could get by with the 1/4". Is Coretec a floating vinyl plank?

 

[lucitedragon]

It is. It's a snap lock product, 1/4" thick with an 1/8" inch cork layer adhered to the bottom.

 

[lucitedragon]

I'm finding two products. There's 1/4" underlayment plywood which is actually 7/32" thick and then 1/4" plywood which is a true 1/4" thick. The underlayment is about $10 less per sheet but also 1/32" thinner. But it specifically says "underlayment" while the true 1/'4" plywood doesn't. Is the 7/32" underlayment plywood what I should go with or do I need to use the true 1/4" plywood that doesn't mention underlayment in the title? Thanks again for you help.

 

[Floorist]

I would use the underlayment plywood.

 

[fcfc]

If the 'ply' layer of you 7/32 plywood looks more like a sticker applique with two layers of some core filler, run away sir run away.

Do not cheap out, use true 5 ply 1/4" underlayment. You get what you pay for with floor prep, do it right.

Additionally, I would definitely put some screws in to firm up the sub floor planking to the joists in your situation, would go a long way to remedy any current squeaks and prevent future issues. Pulling a hardwood floor off in this situation tends to loosen up the framing nails holding your sub floor down if is not already glued and screwed to the joists.

 

[lucitedragon]

This is never easy, is it? So I'm at home depot and they have quarter inch plywood but it has obvious voids on all the edges. I have to assume that means there are voids in the middle which means I really don't trust it. In fact all of their georgia-pacific plywood shows voids. Then they have the 5 millimeter underlayment which everyone raves about on the website. And it looks good. Quality, consistent plys with no voids at all. But 5 millimeters is not even a quarter inch. It's more like 3/16. Is that too thin? Is it better to go thin but quality or thicker with likely voids? And can you use 3/8" OSB instead of plywood?

 

[Ken]

WHOA WHOA WHOA!!!! ABORT! No need for all that. The whole point of coretec is to go over any subfloor. As long as your within the flatness tolerance do not waste your time installing anything over that old subfloor. I install TONS of coretec and it is not your traditional vinyl plank. Make sure you are flat and tighten any loose planks and go right over it.

 

[lucitedragon]

Ken. Really? That's definitely not what most people are saying, but then none of them have worked with Coretec. So I will say that since I posted this question I took an eight foot level and, laying it across the floor found that I've got about a 1/4" dip in the subfloor. A little more than the allowable 3/16". Right down the middle of the house, as if the joists have sagged at their centers over the years. I was thinking of putting down a strip of 30# roofing felt and then putting 5 mm plywood underlayment. If not that how would you fix the dip?

 

[Ken]

I would lay 1/4" plywood in the deepest part of the depression (where it measures @ 1/4" of course), then fill in the remaining void with patch. CoreTec is a go to product for me and the appeal is that it has all the waterproof benefits of regular vinyl plank but it does not telescope imperfections due to its thickness. You definitely do not need to go through all that trouble for this product.

 

[lucitedragon]

When you say patch do you mean leveling compound or something else? It can't be something too liquid or it will just seep between the subfloor planks.

 

[Ken]

yes, leveling compound or self levelor will work. fill the gaps and go over it

 

[lucitedragon]

I'm so glad you responded. I feel like I've been getting a lot of good advice from other people, but not for the right product. I thought it was supposed to be pretty forgiving stuff. So when you say "fill the gaps" what do you mean? Like caulk between the boards and then poor the self leveler so that it doesn't seep into the floor? Any particular leveler brand you'd recommend?

 

[Ken]

I've been using dependable lately but mapei make a nice product too. Just be sure to follow the directions.