subfloor is hardwood planks

I bought a 1945 block/beam farmhouse which needs lots of tlc. In the original bedroom and kitchen/living room areas, the carpet/padding, peel n stick tiles, and then plywood was removed.

Underneath the plywood is hardwood planks, I think they are square edge planks. These planks are my subfloor; they are attached to the joists, the ground is underneath. With the exception of one interior wall, the subfloor was put down after the exterior walls. There was a thin layer between the plywood and hardwood that of course is now heavily attached to the planks, so I have not examined the quality of the planks yet, but so far, most of the planks appear to be in very good condition.

My question: is it reasonable to remove the planks, put down plywood, and then re-attach the planks? This is what I am planning to do. Does this sound feasible to experts? If so, would I clean the planks before removing?

The ceiling and walls have been taken down to studs. This is new for me, but I can do most things, I just do them slowly. There's something special about an old farmhouse.

I looked for a related thread, but only found similar. So, I started a new one.

Any recommendations would be appreciated. Thanks so much :-)

 

Welcome to the forums! Leave the planks and apply 3/4" Advantech over it. What do you plan for a final floor? While you have it down, determine the size of joisting and the spacing between them. Also, if possible, make note of the longest unsupported span of the joists. This will help us in determining the best flooring or if you need to add support.

One thing to keep in mind. Screw all your planks to the joists. It will help prevent squeaks. Apply the advantech without adhesive, and screw it only in the plank field (ie. Do not screw to joists)

 

Good advice except I'd use ring shanked 8D nails instead.
It needs to be fastened every 4" on the edges and 6 to 8" in the field.
It would be 100 times faster and 1/4 the price to use nails.

 

Thank you so much for your responses!

I joined and posted a question, but then I couldn't find this site again! I'd visited so many sites the first month I lost track of where I went and couldn't find it.

Sentimental attachment made me want to keep the original 1945 floors. After closer examination, they were 3.25 wide 3/4" pine tongue and groove hardwood floors. To pull up, lay a plywood subfloor, then reinstall the original floors sounded great at first, but it just wasn't a good idea.

Next I wanted to just keep the floors, with no subfloor. I used a drum sander to remove the layer of smelly, black felt-type paper, but I didn't completely sand down the floors because some areas too delicate, some cupped, some had damage, and the sanding was too risky. Determined to keep the floors, and began the tedious task of trying to securely seal the floors. It was somewhat acceptable, but then the first days of below freezing temperatures made me understand the necessity of a subfloor, plus the beauty of a stable secure floor began to seem more important than the nostalgia of an old floor.

So, back at square one, thanks again for your responses. I want to add a plywood then 3/4" hardwood flooring. You recommended 3/4" Advantech. The original plywood I pulled up was 1/2". Do I need the 3/4" if I am lay it over the original 3/4 " pine or should I stay with 1/2" Advantech?

Do you have any information of there is more VOC in the Advantech compared to regular CDX plywood? Sorry to bring that up, I'm trying hard to keep the VOC down as low as possible. Advantech seems the best choice.

It appears the original floor is nailed securely to the joists in most places; I will confirm that before I begin, thanks for all those important tips.

Last question, do I leave 1/8" between the Advantech and sole plate?

Now to decide nails vs screws :-)

Glad to have found this great site, and I appreciate the tips and advice.

 

Advantech only comes in 3/4" to my knowledge, and you will need the thickness. Advantech meets LEED residential qualities regarding VOC's. The VOC's would have come from the adhesive being used, and since you won't be using adhesive on the second layer, it is a moot point. Yes, leave 1/8" around all perimeters. Ring shank nails with a nailer would be much faster, screws more secure.

 

I'd pass on the screw idea when installing the Advantech.
Ever tried to screw two pieces of wood together?
Once the screw goes through the top piece it starts to push away from the bottom piece leaving a void unless you predrilled a pilot hole in the top piece.
Screws also leave a raised area where the head compressed the wood.
It also would cost at least 4 times as much and take about 10 times as long.

 

The advice sounds great, and so easy to understand, thank you both so much.

I forgot to be specific on the layers, so please forgive me for asking again, even though you may have already stated this indirectly.

I have the original floors, I lay the Advantech directly on top of that, then the new hardwood flooring directly on top of that? No felt, etc., under the Advantech?

Thanks again, I'm very excited to be doing this the right way.

 

No felt UNDER the Advantech, but between it and the new hardwood flooring. Nail the Advantech to the old subflooring, but intentionally miss the joists. If there is any movement, you want it to move between the sheets and not be too rigidly attached to the joists.

 

Underlayment is nailed between the joist to try and pull it down so there is no gap between the joist, not so it can float.
If there's a gap something's going to move and squeak.