MDF & Plywood Subfloor

Leo

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Sep 1, 2003, 4:48:22 PM9/1/03

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I am considering the purchase of a home and need some advice. The subfloor
appears to be MDF over plywood. I don't know the thickness of either -
short of drilling a hole I don't now how to determine this anyway (I can say
that the floors feel very solid). Can I install a (3/4" real wood) hardwood
floor over this type of subfloor? Is there any advantage or disadvantage to
this type of subfloor? Is the installation a typical nail down? Any advice
or consideration given is greatly appreciated.

Also, is MDF over plywood typical? The home was built in 1978.

Leo

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Sep 1, 2003, 7:45:11 PM9/1/03

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After a trip to the Home Depot I believe the underlayment is Particleboard
and not MDF (medium density fiberboard)... they look pretty similar except
the Particleboard appears to be made from larger particles.

Leo

"Leo" <g...@bent.com> wrote in message news:bj0ba5$b4u$1...@bob.news.rcn.net...

Joe Bobst

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Sep 1, 2003, 8:56:18 PM9/1/03

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<< Can I install a (3/4" real wood) hardwood floor over this type of subfloor?
>>

Probably.
But the real wood needs to be well anchored, and plywood IMO has better nail
holding ability. Considering your investment in the hardwood plus labor,
wouildn't it be just good practice to get rid of the sawdust board? It might
even be advantageous to not have to do as much door trimming and such for added
height buildup. Just 2¢ worth...

Joe

Colbyt

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Sep 1, 2003, 8:59:25 PM9/1/03

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"Leo" <g...@bent.com> wrote in message news:bj0lll$673$1...@bob.news.rcn.net...

This method of construction was quite common in the 70's in many parts of
the USA. Usually 1/2-3/4" plywood and 3/4" particle board. Makes a real
strong floor until it gets wet. Then the particle board swells and never
returns to normal. Better builders usually provided a layer of plastic
between the two layers.

The particle board does not have the nail holding ability of plywood but I
can not answer your question about whether or not it would be safe for a
nail down HW floor.

--
Colbyt
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Kitchens Inc.

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Sep 3, 2003, 8:39:28 PM9/3/03

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"Leo" <g...@bent.com> wrote in message news:bj0ba5$b4u$1...@bob.news.rcn.net...

> I am considering the purchase of a home and need some advice. The
subfloor
> appears to be MDF over plywood.
> I don't know the thickness of either -
> short of drilling a hole I don't now how to determine this anyway (I can
say
> that the floors feel very solid).

<>typical plywood subfloor is 3/4" t&g.
<>typical PB (MDF) underlayment is 5/8"

>Can I install a (3/4" real wood) hardwood
> floor over this type of subfloor?

<>Remove the "Particle Board" and install the hardwood perpendicular to your
floor joists.
<>if you do not remove the PB you will have height issues in the adjoining
rooms and/or stairs.

> Is there any advantage or disadvantage to
> this type of subfloor? Is the installation a typical nail down? Any
advice
> or consideration given is greatly appreciated.
>
> Also, is MDF over plywood typical? The home was built in 1978.
>
> Leo

<> the PB (MDF) was probably put down for the installation of a carpet.

<>nail subfloor (under PB) w/8p ring nails before installing the new
hardwood.
<>this will remove the (future) squeaks. (2" coarse thread screws are
another option).

MSH

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Sep 6, 2003, 5:41:28 PM9/6/03

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No. Hardwood should not be installed over particle board. Less nail holding
power and if it gets wet, you will be installing a new floor.

M Hamlin
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