MDF & Plywood Subfloor

[Leo]

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

[Leo]

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

[Colbyt]

disadvantage

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.

[Kitchens Inc.]

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

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.

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]

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.

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