Do you need subflooring under solid wood flooring?

[Wild Turkey]

Looking at possibility of building our "empty nest" house and I got to thinking.

Didn't they used to nail the solid wood flooring to the joists without "subflooring"?

I know there would be "considerations" of board length, etc but the first question is can it be done?

If so I'll work on the other problems as I get to them

[Bob10]

Never seen it but I imagine it has been done.  I myself like 1 1/8 ply glued and screwed down as subfloor

[Robert Adams]

Never seen it done except for a gym floor that was laid over a complex support frame but no subflooring. 

    I wouldn't do it myself for support and moisture control reasons. Even our house built in 1960 by idiots has 1"+ (not 3/4) thick Douglas Fir 5" wide tongue and groove sub flooring on a 45* angle however they didn't put wood flooring down. They covered that with 5/8 Doug fir plywood. I wish I could buy plywood that good today. Only mistake was they nailed it down and nails tend to come out over time(screws weren't invented back then.... so nice today how we have much better ways to fasten than with nails.)

[Kansas City Fireslayer]

I have seen it done in the really old warehouse and freight districts in Kansas City.  Many of these buildings would be considered "timber framed"  I believe many were laid on a diagonal as well.  I would think the extra decking would make any install easier, provide more stability, and add to sound reduction.  I'm sure they changed their ways for good reason.  I wouldn't do it but that's just me.  One thing that you don't see used anymore is the use of "spreaders" in-between the floor joists.  Two 1 x 2's or similar with 45 degree miters on each end and then crossed to keep the floor joists from twisting.  My old house had 16' max code runs and they could of benefited from this given the warp that later occured.

[John Mihich]

Just helped my brother put in new flooring over the original floor.  The original floor was 1 board thick.  I know it was pine about 1 x 12.  We did lay 1/4" underlayment over the floor to even it out some.  Two of the bedrooms still have the same floor.  House was built 1850's.

[Snipe Hunter]

All wood floors used to be done that way. It helped the bugs get from floor to floor unimpeded once it shrunk.
I sure wouldn't do it. It would be exposed while the framing is done so you'll still have to sand and finish is once the roof is on. It would be much easier to buy prefinished floor and install it once the house is built. 
Would you take it all the way to the exterior and set the walls on top of it like a subfloor? If you do, it now becomes the subfloor which in itself isn't an issue but anything you want to do later will have to go on top of it. Hardwood going to the exterior might invite termites too where as 23/32 ply or T&G OSB is more stable and less appetizing to bugs.

[crokett™]

An old (1900 era) house that we salavaged tongue and groove siding out of to match my parents house had flooring laid directly over the joists but I wouldn't do that today.

[tomsteve]

might wanna check local building codes.  im thinkin subfloor may be required.

[John Mihich]

All houses that have carpeting instead of hardwood floors the carpet is laid right on the subfloor - just one layer.  At least that's what I have seen.

[crokett™]

what would be the reason to skip the sublfloor? I can think of several reasons not to. the reasons I can think of to skip it are to save money and potentially time, but I know it will cost you time later on