Nail down hardwood florring parallel to floor joists

Posted by postal on April 5, 2009, 9:16 pm

P.Ostal
-------------------------------------

Hi all

I have open-web engineered floor joists at 19.2" centre, and they run
along the longer length of the living/dining room. I have 3/4" particle
board subfloors glued and screwed every 8" into the joists..

I want to install nail-down 3/4" solid hardwood flooring, and they would
logically go along the longer side of the rooms (and be parallel to the
floor joists).

I have added 3/8" plywood on top of the 3/4" OSB. Screwed into the
subfloor & joists every 6". The reason I used 3/8" ply wood was to get
level with areas that were tiled (using 5/8" plywood underlayment).

Is this sufficient to allow the hardwood planks installed parallel to the
floor joists?
Or should I have used thicker plywood, or even add some support for the
floors from the underneed (i.e., put 2x4 between the floor joist from the
underneath, then glue to the subfloor and screw to side of the joists.

Any advice will be greatly appreciated.

P.Ostal

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Posted by DanG on April 5, 2009, 10:20 pm

I hope you're wrong about particle board. It has never been a
structural flooring material to my knowledge, especially at 19.2
centers. Particle board has been used as underlayment, but it not
even acceptable as an underlayment for nail down hardwood
flooring. Hopefully you meant OSB tongue and groove. If it
doesn't have the T&G it requires nailers at edges. It would be
best if both the OSB and the plywood that you added was glued and
nailed. I've not ever run hardwood on a 19.2 center joist system.
There are no restrictions on which way the hardwood runs when on
sheet goods as far as I know. If it were on lumber decking, it
would need to run opposite the subfloor direction.

--
______________________________
Keep the whole world singing . . . .
DanG (remove the sevens)
dgriff237@7cox.net

> P.Ostal
> -------------------------------------
> Hi all
> I have open-web engineered floor joists at 19.2" centre, and
> they run
> along the longer length of the living/dining room. I have 3/4"
> particle
> board subfloors glued and screwed every 8" into the joists..
> I want to install nail-down 3/4" solid hardwood flooring, and
> they would
> logically go along the longer side of the rooms (and be parallel
> to the
> floor joists).
> I have added 3/8" plywood on top of the 3/4" OSB. Screwed into
> the
> subfloor & joists every 6". The reason I used 3/8" ply wood was
> to get
> level with areas that were tiled (using 5/8" plywood
> underlayment).
> Is this sufficient to allow the hardwood planks installed
> parallel to the
> floor joists?
> Or should I have used thicker plywood, or even add some support
> for the
> floors from the underneed (i.e., put 2x4 between the floor joist
> from the
> underneath, then glue to the subfloor and screw to side of the
> joists.
> Any advice will be greatly appreciated.
> P.Ostal
> ##-----------------------------------------------##
> Delivered via http://www.thestuccocompany.com/
> Building Construction and Maintenance Forum
> Web and RSS access to your favorite newsgroup -
> alt.building.construction - 16150 messages and counting!
> ##-----------------------------------------------##

Posted by lansing on April 6, 2009, 12:32 am

That is the best answer given here below and its on 100%...

Hope the 3/8" plywood you used is made of Douglas fir...that's what we use
under any hardwood ...But We use 5/8" thick sheets...

Lansing

>I hope you're wrong about particle board. It has never been a structural
>flooring material to my knowledge, especially at 19.2 centers. Particle
>board has been used as underlayment, but it not even acceptable as an
>underlayment for nail down hardwood flooring. Hopefully you meant OSB
>tongue and groove. If it doesn't have the T&G it requires nailers at
>edges. It would be best if both the OSB and the plywood that you added was
>glued and nailed. I've not ever run hardwood on a 19.2 center joist
>system. There are no restrictions on which way the hardwood runs when on
>sheet goods as far as I know. If it were on lumber decking, it would need
>to run opposite the subfloor direction.
> --
> ______________________________
> Keep the whole world singing . . . .
> DanG (remove the sevens)
> dgriff237@7cox.net

>> P.Ostal
>> -------------------------------------
>> Hi all
>> I have open-web engineered floor joists at 19.2" centre, and they run
>> along the longer length of the living/dining room. I have 3/4" particle
>> board subfloors glued and screwed every 8" into the joists..
>> I want to install nail-down 3/4" solid hardwood flooring, and they would
>> logically go along the longer side of the rooms (and be parallel to the
>> floor joists).
>> I have added 3/8" plywood on top of the 3/4" OSB. Screwed into the
>> subfloor & joists every 6". The reason I used 3/8" ply wood was to get
>> level with areas that were tiled (using 5/8" plywood underlayment).
>> Is this sufficient to allow the hardwood planks installed parallel to the
>> floor joists?
>> Or should I have used thicker plywood, or even add some support for the
>> floors from the underneed (i.e., put 2x4 between the floor joist from the
>> underneath, then glue to the subfloor and screw to side of the joists.
>> Any advice will be greatly appreciated.
>> P.Ostal
>> ##-----------------------------------------------##
>> Delivered via http://www.thestuccocompany.com/
>> Building Construction and Maintenance Forum
>> Web and RSS access to your favorite newsgroup -
>> alt.building.construction - 16150 messages and counting!
>> ##-----------------------------------------------##

Posted by RicodJour on April 6, 2009, 10:13 am

> I hope you're wrong about particle board. =A0It has never been a
> structural flooring material to my knowledge, especially at 19.2
> centers. =A0Particle board has been used as underlayment, but it not
> even acceptable as an underlayment for nail down hardwood
> flooring. =A0Hopefully you meant OSB tongue and groove. =A0If it
> doesn't have the T&G it requires nailers at edges. =A0It would be
> best if both the OSB and the plywood that you added was glued and
> nailed. =A0I've not ever run hardwood on a 19.2 center joist system.
> There are no restrictions on which way the hardwood runs when on
> sheet goods as far as I know. =A0If it were on lumber decking, it
> would need to run opposite the subfloor direction.

The OP didn't mention the sheet good orientation, and whether his
underlayment was laid with the same orientation, but it makes a big
difference.
http://www.canply.org/english/products/comparison/comparison185.htm

NOFMA lists many different subfloor constructions, but they only
recommend one way to lay the strip flooring - perpendicular to the
joists. The reason for this is that over time, and with load, the
floor will creep. The gaps between strips will tend to open up over
the joists (the gaps are on the top surface of the strip flooring),
and in the "valley" the gaps will be at the bottom of the strips. In
other words you will have banding of gaps.

The floor will also have a shortened lifespan if it is laid parallel
to the joists. The dip between floor joists will probably be minor
(particularly in the OP's situation), but the high points over the
joists will require more sanding to get the floor flat. That means
the nails in the strip flooring over the joists will shine through
after sanding before the nail in the valleys will show up.

I agree with you that the underlayment should have been glued as well
as screwed, but it sounds like the OP did a reasonable job beefing up
the subfloor. How much the strip flooring will move will depend on
the OP's house's particulars - location (for humidity and
temperature), what's underneath the first floor, whether the house is
conditioned year round, etc.

R

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