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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'>I have 4 projects done with ply over eps. The first was 3” eps foam over concrete slab with 5/8 ply w/ wood and tile flooring over (tile area had a 2<sup>nd</sup> layer of ½” ply over). I visited it after 10 years and it was fine. Subsequent floors have been eps over sand base with ply laminated. I’ve not used anything less than 3” as there is some reliance on the foam to span any voids or deflections. Also it is difficult to lay and set 1” sheets. <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 the concrete slab application the floor was levelled (high spots ground out and a levelling mix like quickcrete). <o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Polyurethane foam is the most reliable bonding adhesive for eps foam board (low expanding type rated for subfloor – enerbond or equiv.) laid in a squiggle pattern at 3” o.c.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Sheets need to be weighted till the adhesive forms its initial set – flat weights (16x16 ply square with about 30lbs – conc block or bucket with sand works nicely). I think for 1” weight spacing would be about 3’ o.c.. If you cut the sheets to 4’ you can leapfrog the weighting. <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'>Seams were foamed and then shaved. Ply is laid with the same adhesive pattern (seams staggered over foam). With 5/8 or ¾ t&g ply the end seams are foamed and splined (biscuit at 16 o.c. or something equivalent). Ply has to be weighted as well and needs to be flat (not deformed). 2 layers of ½ “ are nice (no end joining) and for wood floor over - the second layer was foam glued and screw fastened a 6” on edge and 10” field or for tile- at 3” o.c. <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'>Makes a nice floor – no tile/grout movement (without ditra)<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'>With 1” foam I would be tempted to use a stucco basecoat adhesive (designed for eps foam) with a notched trowel (3/8x3/8) for laying the foam sheets to the concrete. Depends on how the concrete was finished. <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'>Since the floor is tile I would simplify the installation and materials used by using 1.5” foam with ½” layer of cemboard laminated over (with seams taped). This would be as stiff as the 2x ply and the cemboard installs nice and flat (i’ve used this over foam with tile). Both of these assemblies are quite stiff in comparison to a normal joist floor so not sure what the need for the ditra is.<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>Alan Abrams<br><b>Sent:</b> May-31-11 5:05 AM<br><b>To:</b> listserv Green Building new<br><b>Subject:</b> [Greenbuilding] fastening a subfloor over foam over a slab<o:p></o:p></span></p></div><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal style='margin-bottom:12.0pt'>does anyone have a reliable spec for fastening a subfloor over foam, over a slab? my recollection is that JLC or FHB had an article on this, but cannot google it up.<br><br>space is very tight in this case; allowing for 1" of xps, two cross plies of 1/2" cdx, and finish flooring (tile on Ditra), to stay within code ceiling height...<br><br>AA<br><br clear=all><b><span style='color:#006600'>Alan Abrams<br>Abrams Design Build LLC</span></b><span style='color:#006600'><br><i>A sustainable approach to beautiful space</i><br></span><span style='font-size:10.0pt;color:#006600'><br>6411 Orchard Avenue Suite 102<br>Takoma Park, MD 20912<br>office 301-270-NET- ZERO (301-270-6380) <br>fax 301-270-1466 <br>cell 202-437-8583<br><a href="mailto:alan@abramsdesignbuild.com" target="_blank"><span style='color:#3333FF'>alan@abramsdesignbuild.com</span></a></span><span style='font-size:10.0pt;color:#3333FF'><br></span><span style='font-size:10.0pt;color:#006600'><a href="http://www.abramsdesignbuild.com/" target="_blank"><span style='color:#3333FF'>www.abramsdesignbuild.com</span></a></span><o:p></o:p></p></div></body></html>