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<DIV>I missed a few emails from a few days ago. The slab is elevated, not on
grade. The engineering analysis and calculations have been done and the subfloor
is more than adequate to resist deflection and everything else. And the house
has shown zero signs of settling (per an expert engineer who inspected the
house, as well as others). So the floor is not deflecting at all.</DIV>
<DIV> </DIV>
<DIV>What aspects of “placement of the slab?” in the comment below by Alan
Abrams could cause problems, please?</DIV>
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<DIV style="font-color: black"><B>From:</B> <A title=alan@abramsdesignbuild.com
href="mailto:alan@abramsdesignbuild.com">Alan Abrams</A> </DIV>
<DIV><B>Sent:</B> Tuesday, May 14, 2013 7:59 AM</DIV>
<DIV><B>To:</B> <A title=greenbuilding@lists.bioenergylists.org
href="mailto:greenbuilding@lists.bioenergylists.org">Green Building</A> </DIV>
<DIV><B>Subject:</B> Re: [Greenbuilding] Passive solar home--concrete overlay
rethermalmass</DIV></DIV></DIV>
<DIV> </DIV></DIV>
<DIV
style="FONT-SIZE: small; FONT-FAMILY: 'Calibri'; FONT-WEIGHT: normal; COLOR: #000000; FONT-STYLE: normal; TEXT-DECORATION: none; DISPLAY: inline">coupla
things--
<DIV> </DIV>
<DIV>1. I assumed the slab was on grade</DIV>
<DIV>2. I was not referring to removing insulation, I was talking about removing
the slab if it were known that there was not sufficient insulation beneath
it.</DIV>
<DIV> </DIV>
<DIV>that said, if the slab is over a frame floor and it is failing, then the
first task is to diagnose the cause of failure. Is the frame adequate to
resist deflection? or was the failure due to the reinforcement, mixture,
and/or placement of the slab? Or both? </DIV>
<DIV> </DIV>
<DIV>if the floor is deflecting (more than, say, L/480), all bets are off, and
whatever is placed over the existing slab would be bound to fail as
well.<BR><BR>AA<BR><BR>
<DIV class=gmail_quote>On Tue, May 14, 2013 at 8:02 AM, KTOT (g) <SPAN
dir=ltr><<A href="mailto:ktottotc@gmail.com"
target=_blank>ktottotc@gmail.com</A>></SPAN> wrote:<BR>
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<DIV>Thank you for the comments.</DIV>
<DIV> </DIV>
<DIV>However, I’m not completely sure what you’re saying about insulation.
Removing the insulation provides the opportunity to install what? There is a
very good layer of expensive blow-in insulation under the slab, between the
two floors, and the ceiling downstairs is finished. No way is that insulation
coming out without destroying much of my house. </DIV>
<DIV> </DIV>
<DIV>The point on more mass furthering the cycle is good. The slab is already
thicker than my designer planned for the house so already probably is somewhat
retarded.</DIV>
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<DIV> </DIV>
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<DIV><B>From:</B> <A title=alan@abramsdesignbuild.com
href="mailto:alan@abramsdesignbuild.com" target=_blank>Alan Abrams</A> </DIV>
<DIV><B>Sent:</B> Tuesday, May 14, 2013 5:18 AM</DIV>
<DIV class=im>
<DIV><B>To:</B> <A title=greenbuilding@lists.bioenergylists.org
href="mailto:greenbuilding@lists.bioenergylists.org" target=_blank>Green
Building</A> </DIV>
<DIV><B>Subject:</B> Re: [Greenbuilding] Passive solar home--concrete overlay
re thermalmass</DIV></DIV></DIV></DIV>
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<DIV>one consideration here is that capping an existing slab in a passive
solar system that presently works "extremely well"-- that is, adding more
mass--is not necessarily more better. more mass will retard the cycle of
heating and cooling, changing the character of thermal comfort. if the
cap is thin enough, maybe it won't be noticed--but this is all
quantifiable.</DIV>
<DIV> </DIV>
<DIV>it all raises many questions--about the climate, about the substrate
under the slab, about the details of the envelope of the house--all factors
that come into play in this decision. maybe there is not much insulation
under the slab, so that removing it provides the opportunity to install
it. if there is adequate insulation under the slab, then maybe a thin
cap is in order. </DIV>
<DIV> </DIV>
<DIV>on the subject of thermal mass and heat transfer, I think RT's earlier
reply was definitive. thermal mass is simply a function of density or
specific gravity, and an acrylic admixture and/or thin film of bonding
compound between original and new slabs would neither change the density of
the slab or retard conductive heat exchange between the two in any significant
way.</DIV>
<DIV> </DIV>
<DIV>some time ago on this list serve, back in the pleistocene era, IIRC,
there was a discussion on high strength, super thin slabs, akin to
ferro-cement boat hulls--which might have application here. someone with
even more time than I have to waste could look it up. </DIV>
<DIV> </DIV>
<DIV>AA</DIV>
<DIV> </DIV>
<DIV><SPAN style="COLOR: rgb(102,0,0)">Alan Abrams</SPAN><B
style="COLOR: rgb(102,0,0)"><BR></B><I><SPAN
style="COLOR: rgb(102,102,102)">certified professional building designer,
AIBD<BR>certified passive house consultant, PHIUS</SPAN></I>
<DIV><I><SPAN style="COLOR: rgb(102,102,102)">certified passive house builder,
PHIUS</SPAN></I><SPAN style="COLOR: rgb(102,0,0)"><FONT
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