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</o:shapelayout></xml><![endif]--></head><body lang=EN-CA link=blue vlink=purple><div class=WordSection1><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Hi Reuben<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>If you want a ‘finished’ surface use the ˝” 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.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'> 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.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>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.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>John<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><div style='border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0cm 0cm 0cm'><p class=MsoNormal><b><span lang=EN-US style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>From:</span></b><span lang=EN-US style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'> greenbuilding-bounces@lists.bioenergylists.org [mailto:greenbuilding-bounces@lists.bioenergylists.org] <b>On Behalf Of </b>Reuben Deumling<br><b>Sent:</b> April-03-12 9:33 AM<br><b>To:</b> Greenbuilding<br><b>Subject:</b> [Greenbuilding] sealing plywood floor?<o:p></o:p></span></p></div><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>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? <br><br>Thanks.<br><br>Reuben<o:p></o:p></p></div></body></html>