203mm (8 inch) outside diameter. To minimise the effect of breaking through the
vapour control layer (VCL), if possible, cut the hole approximately 10mm undersize so
that the sleeve will be forced through the layer. A recommended technique for cutting
the inner leaf is shown in figure 14.
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Fit the non-combustible sleeve to the inner leaf. The sleeve must extend to be at
least flush with the breather membrane / timber sheathing but must not protrude more
than 10mm into the cavity.
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The annular gap between the flue unit and the sleeve must be sealed to prevent
air heat and moisture passing along it. The 12.5mm insulating sheet (See section 8.3)
can be used for this. Do not permanently fix the insulating sheet to the wall at this
stage (See section 9.2).
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©
GDC Group Ltd. 2014
INSTALLER GUIDE
Figure 14. Timber frame wall preparation
