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style="FONT-STYLE: normal; DISPLAY: inline; FONT-FAMILY: 'Calibri'; COLOR: #000000; FONT-SIZE: small; FONT-WEIGHT: normal; TEXT-DECORATION: none">As
described in previous messages, I am planning on installing 12” eps foam boards
on top of 7/16”osb roof sheathing with 2x4 furring strips at 2’oc for nailing
corrugated roofing to. The exterior walls are similar with 2x3 furring
strips aligned with studs over 6”eps over 7/16 osb. </DIV></DIV>
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style="FONT-STYLE: normal; DISPLAY: inline; FONT-FAMILY: 'Calibri'; COLOR: #000000; FONT-SIZE: small; FONT-WEIGHT: normal; TEXT-DECORATION: none"> </DIV></DIV>
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style="FONT-STYLE: normal; DISPLAY: inline; FONT-FAMILY: 'Calibri'; COLOR: #000000; FONT-SIZE: small; FONT-WEIGHT: normal; TEXT-DECORATION: none">I
am planning the osb and eps rows to be perpendicular so that only at the
intersections will there be a continuous potential leak. I want to manage
both the eps and the osb to be a continuous air barrier. Only one is
required to achieve performance. However, the vulnerability to execution
flaws, even when you are trying, makes me want to manage both layers to provide
a redundant continuous air barrier. </DIV></DIV>
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<DIV
style="FONT-STYLE: normal; DISPLAY: inline; FONT-FAMILY: 'Calibri'; COLOR: #000000; FONT-SIZE: small; FONT-WEIGHT: normal; TEXT-DECORATION: none"> </DIV></DIV>
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style="FONT-STYLE: normal; DISPLAY: inline; FONT-FAMILY: 'Calibri'; COLOR: #000000; FONT-SIZE: small; FONT-WEIGHT: normal; TEXT-DECORATION: none">The
osb would be installed conventionally with plywood clips between rafter top
chords. This creates a continuous gap the thickness of the metal
clip. Can someone recommend a tape that will not give up in time?
Would sealing it with acoustic caulk be practical, maybe from the top
side?</DIV></DIV>
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<DIV
style="FONT-STYLE: normal; DISPLAY: inline; FONT-FAMILY: 'Calibri'; COLOR: #000000; FONT-SIZE: small; FONT-WEIGHT: normal; TEXT-DECORATION: none"> </DIV></DIV>
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<DIV
style="FONT-STYLE: normal; DISPLAY: inline; FONT-FAMILY: 'Calibri'; COLOR: #000000; FONT-SIZE: small; FONT-WEIGHT: normal; TEXT-DECORATION: none">The
foam will be air sealed at the seams with acoustic caulk. As a third air
barrier, I might consider tape at the foam seams on top. I am going to put
a dab of caulk on the bottom of the furring strip where the pilot holes show
where the screw will penetrate the full thickness to seal that potential
leak. Another potential air barrier is to cover all the foam with a
plastic or tight building wrap before installing the furring strips.
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<DIV
style="FONT-STYLE: normal; DISPLAY: inline; FONT-FAMILY: 'Calibri'; COLOR: #000000; FONT-SIZE: small; FONT-WEIGHT: normal; TEXT-DECORATION: none"> </DIV></DIV>
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<DIV
style="FONT-STYLE: normal; DISPLAY: inline; FONT-FAMILY: 'Calibri'; COLOR: #000000; FONT-SIZE: small; FONT-WEIGHT: normal; TEXT-DECORATION: none">If
I am able to achieve to my satisfaction the air barrier in osb and eps layers, I
should not need the membrane layers. Since the foam is 6” and 12” thick, the
nails from installing finished materials penetrating .5” or so into foam should
not threaten the air barrier if it does not fall at a seam. </DIV></DIV>
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style="FONT-STYLE: normal; DISPLAY: inline; FONT-FAMILY: 'Calibri'; COLOR: #000000; FONT-SIZE: small; FONT-WEIGHT: normal; TEXT-DECORATION: none"> </DIV></DIV>
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<DIV
style="FONT-STYLE: normal; DISPLAY: inline; FONT-FAMILY: 'Calibri'; COLOR: #000000; FONT-SIZE: small; FONT-WEIGHT: normal; TEXT-DECORATION: none">You
comments, as always will be appreciated. </DIV></DIV>
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<DIV
style="FONT-STYLE: normal; DISPLAY: inline; FONT-FAMILY: 'Calibri'; COLOR: #000000; FONT-SIZE: small; FONT-WEIGHT: normal; TEXT-DECORATION: none">Eli
</DIV></DIV>
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<DIV
style="FONT-STYLE: normal; DISPLAY: inline; FONT-FAMILY: 'Calibri'; COLOR: #000000; FONT-SIZE: small; FONT-WEIGHT: normal; TEXT-DECORATION: none"><A
href="http://www.conservationarchitect.net">www.conservationarchitect.net</A>
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