So we're building a new house and trying to make it as healthy as possible by avoiding materials that outgas harmful substances. One of the big ones is formaldehyde, which is outgassed by most types of engineered wood products. Right now I'm thinking about materials for subfloor. Something like DragonBoard would be ideal, but it's somewhat cost-prohibitive (4x times the cost of OSB or plywood subfloor in my area). Another clean option that is very cheap (minus labor, which I'm going to be putting in myself) is doing it the old-fashioned way and making the subfloor out of individual planks. The cost of materials is equivalent to OSB, maybe even a little cheaper because I can get the wood at a local lumber mill. Is there a reason why this would be a terrible idea, other than the amount of labor? I'm probably missing something obvious and this is a stupid question... I would appreciate if you play nice...

(Note: I'm not after making the house "green" or scoring LEED points. I'm after removing toxic chemicals. If it means I have to make the floor joists out of whale bone and make the subfloor out of hammered panda leather, we can do that too! :D)

nysharps, ...Nothing wrong with that.......... ..........just make sure that the boards are seasoned or kiln dried.Otherwise if stll green will shrink and twist terribly

Don't you want Tongue & Groove for that?

S4S boards will work for the subfloor, if there is to be a finished wood floor over it , it should be T&G with a layer of 15# felt in between

I didn't think of putting the planks diagonally across the joists...

Is there anything I should know/keep in mind about making this type of sub-floor? The lumber I will be getting is kiln-dried, but would there be greater risk of warping if moisture gets in, compared to OSB or plywood?

Posted By nysharps on 12 Jun 2013 11:14 PM
I didn't think of putting the planks diagonally across the joists...

Is there anything I should know/keep in mind about making this type of sub-floor? The lumber I will be getting is kiln-dried, but would there be greater risk of warping if moisture gets in, compared to OSB or plywood?

Is this for a 1st floor or 2nd floor? What kind of foundation/slab are you going with?

According to AdvanTech's literature, it contains no urea formaldehyde.

http://www.advantechperforms.com/technical-information/technical-tips-detail.aspx?tt_section=tips&tt_id=ff66ce13-8864-458c-b80e-81a67b05e09d

In fact, most if not all exterior grade plywood, OSB, and sub-flooring doesn't contain urea formaldehyde.

Posted By nysharps on 12 Jun 2013 11:14 PM
I didn't think of putting the planks diagonally across the joists...

Is there anything I should know/keep in mind about making this type of sub-floor? The lumber I will be getting is kiln-dried, but would there be greater risk of warping if moisture gets in, compared to OSB or plywood?

Diagonally makes for a much stronger system.
make sure if their is basement or crawlspace that you use a vapor barrier under slab or over dirt, I don't see any greater risk for warping, if it happens it will be long before any finished floors go down and you can address the issue then

Posted By arkie6 on 13 Jun 2013 06:21 AM
According to AdvanTech's literature, it contains no urea formaldehyde.

http://www.advantechperforms.com/technical-information/technical-tips-detail.aspx?tt_section=tips&tt_id=ff66ce13-8864-458c-b80e-81a67b05e09d

In fact, most if not all exterior grade plywood, OSB, and sub-flooring doesn't contain urea formaldehyde.

The keyword there is "urea formaldehyde". They contain phenol-formaldehyde instead.
There are plywoods that use formaldehyde-free adhesives, but they're a bit more expensive. I'm considering them too.

This will be on the 1st and 2nd floor with a full basement underneath. I wasn't sure what to do in the basement, that was going to be my next question.

Also, the diagram of the plank subfloor above shows a ledger board. I was planning to use Watkins hangers (http://watkinshanger.com/) which would mean that I wouldn't have a ledger board. How would I work around that?
Edited to add: Figured that one out with the help of a friend. I would just screw dimensional lumber to the webbing in the ICF between the joists and along the sides.

I know this is an older thread but I am confronted with the same dilemma, the chemical free aspect does intrigue me more than anything, my other motivation is that my lot was wooded and I cut down lots of fully grown cottonwoods just to make room. Now I am not looking for a cheap easy way out osb would have been the ticket, the labor will probably out weigh the cost I am aware of that. but I have these large 4'+ wide cotton wood logs, they are not much good for anything else so why not, I have been looking for an excuse to buy a saw mill and possibly cut the rest of the lumber with, obviously out of some harder woods. so back to planking, I am curious as to what the OP decided for one, the other for the most of my research 1x planking was traditionally used for subfloors, sheathing and roof, that is 3/4 inch thick, 8 inch wide being most common thou 6 and 4 have also been used. cupping or twisting during drying is a concern, depending which part of the trunk the board came from cottonwood can shrink Shrinkage: Radial:3.9 %, Tangential: 9.2%, Volumetric: 13.9%, T/R Ratio: 2.4 ( http://www.wood-database.com/lumber-identification/hardwoods/eastern-cottonwood/ ) waste is not much of a concern to me as I have enough for 2 houses so I am considering quarter sawing, I have been advised that further jointing and planning would be required in order to do shiplap or T&G, quarter sawing will be more labor intensive but hopefully the boards wont deform as much or whatever twist may develop will be consistent throughout the batch, possibly making the rest of the job less work. one other thing I was considering is cut the boards a little more than twice the intended width, and re saw them after they have been seasoning for a while, after they have deformed some, so that the new cut will be straight and hopefully not deform much further, this will also give me a flat surface to reference off of while planning. I am hoping some old timers may know more about this task I am about to take on and offer some tips, all above are my conclusions based on other articles I came across, experience, none,