Hello Forum members!

Looking for practical advice on a topic that is apparently not normally found. Or at least I can't find anything. What I will describe may be unusual, but is it possible to get good results, and what are the factors that must be attended to?

An Atlanta area NWFA member/contractor is willing and ready to install 1500 SF of 3/4" x 4-3/4" T&G prefinished solid Acacia directly on my existing white oak floor, by gluing and stapling. The desire is to avoid removing the old Oak, which involves cutting out where some remodeled walls rest on the Oak.

RUN DOWN OF THE CIRCUMSTANCES:
- Main floor is joists over a dry basement, with original 3/4" plywood subfloor
- Half the main floor is still covered with original 3/4" x 2-1/4" white oak, 18 years old. The original Oak appears flat, stable, and does not show gaps even in winter.
- The other half was carpet, which was recently replaced with TruFlor 3/4" T&G OSB, thoroughly screwed down.
- So the old oak and new OSB are flush where they meet in various places
- The goal is to cover the entire main floor in 3/4" x 4-3/4" Acaia, over the Oak and OSB
- The NWFA contractor claims to have experience successfully doing this

PROPOSED STEPS:
- rough sand through the old finish on the oak to promote glue adhesion
- Install Acacia over white oak and TruFlor OSB using urethane glue AND staples into Oak (and OSB)
- Maintain same orientation of the wider Acaia over the narrower Oak

MY QUESTIONS:
- Is there any way this can come out good, and what will it take?
- Where can I get reliable information about doing this, and detailed explanations?
- Will it be possible to drive staples into the old white oak?
- What can go wrong, and why?
- Will the glue help assure a solid installation?

Thank you for your thoughtful advice!
James in Marietta, Georgia

What really concerns me here is he wants to install the new wood over the existing wood in the same direction. I think this is setting you up for having gaps in your new floor that mimic the gaps of the floor beneath. One alternative is to install the new floor on a 45 degree angle to the existing.

Hi Chickensalad. Thank you for your thoughts.

Indeed, running the same direction is one of the concerns I am getting from "researching" various forums, etc. My hope is that knowing and understanding the threats, I can pursue with success. The hard part is having certainty.

With the same direction installation, the hope is that since the old wood is not gapping (up to now, that is) , and since the new boards are wider, each one spans across two of the older boards.

One professional thinks that nailing (stapling?) into the old oak will be difficult, and that many nails will bend up and not go in. Any experience with nailing into oak as the subfloor?

You shouldn't have a problem with nails or staples. To be safe, you may choose to use nails for the install.

I personally would be hesitant to install over the existing oak. As for cutting out the existing oak because of walls, there are plenty of tools that would make it simple enough to do--sawzall, multi-tool, and/or toe-kick saw. It is probably a partition wall. Just remove the baseboard and go to town.

I also hesitate to install hardwood over hardwood. But there is much work to save by doing it, so I'm trying to get a deeper understanding of the factors that would make it a success or a failure. I'm looking for documented science and engineering. Are there methods and precautions that could make the difference?

Thanks again for your views.

James

That's Stephens department. He's into research...

Aside of what others mention...good points!

What about the new floor height going over the old and OSB. I'm sure they've looked at that though.

I'm also surprised an NFWA member okays going in the same direction, even if it's glued. I think I know the guy if you're working with LL. Maybe somebody has had success with it. Those two hardwoods have different expansion characteristics. I'm thinking they could fight against each other?

Probably too late for removing the old hardwood, or so it sounds.

Here the hardwood (video link) was removed. Otherwise. Forget using the dishwasher, and it had to be the same height as an adjoining travertine floor. It would have caused other issues too.

https://www.youtube.com/watch?v=OnYgqH6EKNw

Hi Ken,

Most interesting would be to know the outcomes from direct experiences in putting new solid hardwood over old solid hardwood, especially with similar circumstances of nailing, gluing, wide plank over narrow, same direction vs. crossed, etc.

No problem with floor heights in my case, as the doors and dishwasher have enough leeway.

If changing the orientation crosswise is an important way to reduce the risk, then it should be done that way. I would really like to get a better feel for what the risk drivers are.

Is gluing something that will greatly reduce the risk of boards coming up or gapping? Would gluing to the old wood cause it to pull loose of its nails?

Would you glue a 4-3/4" plank without nails, or are a few nails important to get the board down flat on the glue.

In general, is what I'm wanting to do known to be disastrous, or is it just a big unknown because it is a topic that is rarely addressed?

Not too late to remove the old wood I suppose, just much more work. Must cut around a new island that was built on top of the oak, and some new walls the same.

Thank you for the video, and your thoughts!

James

>I'm also surprised an NFWA member okays going in the same direction, even if it's glued. I think I know the guy if you're working with LL. Maybe somebody has had success with it. Those two hardwoods have different expansion characteristics. I'm thinking they could fight against each other?

The installed was not working for LL. And the wood came from F&D.

I hadn't considered the different expansion characteristics. Yikes.