page 4
www.jayline.co.nz
NOVEMBER 2017
REDUCING CLEARANCES TO COMBUSTIBLE WALLS
In the event it is necessary to reduce the clearances to combustible surfaces, it must always be
done in accordance with the safety standard AS/NZS2918:2001 Section 3, Tables 3.1 and 3.2
The shielding shall be constructed from a heat resistant material. The shield must be fixed to the
surface that requires protection and NOT the heater.
The standard allows three options to reduce the stated clearances:
Single Layer of continuous material with minimum Air Gap of 12mm to achieve a clearance factor
of 0.40
Single layer of continuous material with minimum Air Gap of 25mm to achieve a clearance factor
of 0.30
Two spaced Layers of continuous material with minimum Air Gap of 12mm + 12mm to achieve a
clearance factor of 0.20
The shielding must be open at the top and bottom (vented) to allow a continuous air flow. It is
this flow that keeps the surface requiring protection cool. Fixings should not impede this air flow.
The shielding needs to go far enough along and up the wall so that the original side and rear
required clearances are not compromised. As the flue is now closer to the wall the shielding
should also protect the wall from the flue pipe.
Example:
• Side wall clearance for the Jayline FR300 is 290mm
• A 12mm gapped shield on the wall with a factor of 0.40
• Calculate: 290mm x 0.40 = 116mm (This is the new sidewall minimum clearance)
• The shielding needs to be large enough that none of the original clearances of 290mm are
compromised.
