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E
X P A N S I O N /CONTRACTION - Poly liner will expand
as temperature increases and contract as temperature decreases.
Do not install poly on a cold day. "Condition" poly and building
or equipment at 45° or above (the hotter the better), for 24 hours
prior to installation, to minimize expansion. A heated milkhouse
or direct sunlight works good (elevate liner off cold floor/ground
and unroll for quicker heat absorption).
Allow 1/16" of expansion/contraction per foot (both lengthwise
and widthwise - for variations from "average" temperature).
If installed when temperatures are below the "annual average",
allow for more expansion than contraction. When temperatures are
above the "annual average", allow for more contraction than expansion.
Holes in poly should be drilled up to 1/8" oversize depending
on installation temperature.
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WHEN
TO LAG - Manger-liner is not lagged down, but
is free to expand without pushing against nail anchors and humping
(see "Poly Holddowns" for more
information). Conveyor, gutter, and barn cleaner chute liner are
fastened only at the intake end of each section of liner,
and the sections are overlapped 2" - lag front edge of each bottom
section only.
For other applications where the liner is fastened at several
locations (vs just at intake end of each section), drill oversize
or slotted fastener holes. Do not butt sections of liner tightly
together. Instead, provide expansion joint - 1/16" per foot (silicone
caulk to prevent moisture and material from seeping under) - on
wider joints, some installers will use "shiplap" design.
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