Hi All -

My husband and I are replacing all of the hardwoods on our first floor with Hallmark Floors Prefinished Engineered Flooring, 5 inch wide. We intend on doing the nail down method rather than gluing or floating.

Our house is early 1920's, and we spend a good portion of the day removing our existing wood flooring, which is 1/4" thick oak slats (It doesn't seem at all like an actual flooring product. Under that are what we believe to be the original hardwoods, because under that wood are a bunch of newspapers from 1921, which I believe was put down as a moisture barrier. Under the paper are the original old floorboards of the house.

In the kitchen, we tore up all of the original hardwoods and put down a plywood subfloor, because the kitchen had several layers of flooring and glue stuck to it.

However, in the rest of the house, we were hoping that the old hardwoods would be suitable to install our engineered flooring over. We've now torn up the top layer in the living room, and I'd like to get some opinions on the suitability. I'm inclined to think it's not good enough, and we should tear it up and put plywood down. The looks very dirty, I think they just left it there when they repainted, and then put the new flooring over it. It's not super smooth either - it's reasonably flat but there are some places where some boards are slightly (Probably no more than 1/16") than the board next to it.

I've attached some photos - the overall is of course, the overall. You can see at the bottom of the picture some of the flooring we took up. I also attached a close up of one of the worst spots in terms of the boards being flat, as well as a shot where I put the camera on the floor so you can kind of see the overall flatness.

I'm an architect and I have a good sense of how wood and products work, but I've never installed it before. We definitely want to do the right thing - and so if that means tearing it up and putting down plywood, that's what we'll do. I just know that sometimes I have a tendency to be overly cautious, so if it looks legit to everyone here, I'll definitely take that into consideration.

Thanks for any help!
Kim
https://drive.google.com/file/d/0B8rmgYFVs0RCdXRya0U1YzdPd1U/view?usp=sharing
https://drive.google.com/file/d/0B8rmgYFVs0RCeFZ5MEh1Ny1nSmc/view?usp=sharing
https://drive.google.com/file/d/0B8rmgYFVs0RCZWpEeHc0ZXJOVVk/view?usp=sharing

The sub-floor will be great for nailing an oak floor down.
Make sure that any loose planks are nailed down, then cover with a good moisture barrier/ building paper. Follow the manufacturers nailing schedule.
Solid plank sub-floors are stiffer than plywood. Go across the planks or parallel to them.

Pete, I would be installing perpendicular to the old hardwoods - I've read and have been told from multiple sources that you never install a new hardwood parallel to an existing hardwood when installing over it. Have you heard different?

Also, our flooring is hickory, if that makes a difference.

The only thing I am concerned about with the slight unevenness is that the individual new planks that we put down would not be even - and since they are prefinished, we wouldn't be sanding them down to take care of it. Does that give you any concern?

Thanks!

You have a solid sub-floor. You can lay a new floor any direction over it.
There may be a slight difference in the sub-floor planks, but this is not a problem if it is fastened down well. If you would like to have a perfectly flat sub-floor you could use a sander and sand the over wood off. The engineered flooring will go over slight differences in sub-floor height. The new flooring will be fine with the t&g keeping it all flat. There may be thicker or thinner pieces of the engineered flooring, but I am talking about thousandths of an inch. This is remedied by the micro-bevel between planks.
Hickory is known to be susceptible to movement across the grain because of varying humidity levels in the air over the seasons. Using engineered hickory helps solve this problem, with a thin "veneer" glued to the plywood backing, since plywood is so stable.
Covering the old sub-floor with kraft paper by Aqua Bar will provide a clean surface to work over so you don't need to worry about how clean it is as long as it has been broom cleaned before the paper. Scraping off old paint or plaster that is over an eighth of an inch thick is all you need to be concerned with, as long as you have used a straight-edge to check the flatness and it is within a quarter inch in six feet.
If the sub-floor is not flat you need to sand it or build up low areas to make it flat.
If you have bumps in the sub-floor they will telegraph through the new flooring and may affect the wear of the new flooring, as you tend to just clear the floor when walking, and will scuff the finish if there is a hump.