[Greenbuilding] sealing plywood floor?

[John Salmen]

Hi Reuben

 

If you want a ‘finished’ surface use the ½” exterior sheathing for the base
layer and then if you can get a formaldehyde free particle board or mdf
board for the top use that as a working surface – in fact you could do both
layers with particle board as it is actually a flat product and in this
usage is not subject to moisture.  The problem with ply now is that the
product out there seems to be at the lowest edge of the standard. It is hard
to get flat sheets and the void content is huge. Even with ‘good one side-
sanded’ you will have patches blowing out and edges deforming.  Even the
marine grade has voids which it is not supposed to.

 

I recently had a client that was on a low budget so I specified two layers
of particle board instead of ply and it actually was much easier for the
crew that did it as the sheets lay flat in the glue-up and the bond was more
reliable.  So for a shop floor - I would do one layer of ply or exterior
grade tongue and groove particle board and then one layer of mdf –
staggering the seams. Adhesives can actually replace screws so with the foam
adhesive or a poly liquid adhesive you could minimize screwing and then
fill.  The real trick with this assembly is having sheets lay flat to
minimize the need for weighting down buckled and warped sheets. Surprising
how many buckets filled with sand or conc blocks are needed in laying it up.

 

For longevity a 2 part polyurethane paint over mdf is pretty bulletproof but
overkill. Technically the 2 parts are ‘inert’ upon cure but I don’t believe
that anymore and it is quite toxic on application. It is a shop – basically
any floor paint and then it takes on character as you will never repaint it.
MDF is a friendly shop surface and you could oil it as a sealer (tung oil?).
My shop has a few mdf counters that are going on 10 years without any finish
and they are fine – nice beige colour.

 

John

 

 

 

From: greenbuilding-bounces at lists.bioenergylists.org
[mailto:greenbuilding-bounces at lists.bioenergylists.org] On Behalf Of Reuben
Deumling
Sent: April-03-12 9:33 AM
To: Greenbuilding
Subject: [Greenbuilding] sealing plywood floor?

 

I'm planning on assembling a floating double layer of 1/2" plywood over foam
over sand that JOHN SALMEN described here in the past, and as this is for a
basement wood shop I'm wondering if anyone has suggestions about what to
seal or paint the plywood with to maximize its longevity? 

Thanks.

Reuben

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