Fig 5.
ROPE SEAL
WALL LINER
FLUE
FLUE SEAL
TIMBER FRAME CONSTRUCTION
MOISTURE
BARRIER
9
9.1 For installation on walls constructed or comprising combustible materials, reference should be made to the
requirements of BS 5440 and the Building Regulations.
9.2 Timber Framed Housing: For a timber framed house, the fire can be installed as directed in The Institute of Gas
Engineers Utilization Procedure
IGE/UP/7 GAS INSTALLATIONS IN TIMBER FRAME BUILDINGS.
9.3 The combustible wall kit is suitable for walls in which the combustible part is not more than 195 mm thick measured
from the inside of the building.
9.4 The combustible wall kit required is
ÿ
No. 994530. If the whole of the wall is of combustible material, the outer wall
plate must be used, requiring access to the outside of the building.
9.5 If the screws and the wall plugs supplied are not suitable for a particular application, proprietary cavity wall fixings may
be used.
9.6 Proceed as detailed in Section 8.0 Rebated Surround Installation
EXCEPT
for the following points: -
(a) Cut the hole for the flue to a diameter of 178 mm through the plaster board taking care not to damage the Vapour
Control Layer (VCL).
(b) Cut the VCL 10 mm less in diameter than the hole just cut in the plasterboard. This will ensure a seal around the
flue liner.
(c) Continue the 178 mm diameter hole through the remainder of the combustible material. If the outer leave of the wall
is constructed of non-combustible material then cut the hole 135 mm diameter making allowances for the shrinkage
†
of the timber frame.
(d) Measure the thickness of the combustible part of the wall and cut the flue liner to this length, cutting off the end
without the fixing brackets. Fit the liner to the sealing plate using the screws provided.
(e) Push the liner through the VCL taking care not to damage the VCL, and ensuring that the liner
DOES NOT
protrude
into the cavity by more than 10 mm.
(f) If the wall is wholly of combustible material, install the outer wall plate centrally over the hole from the outside as
shown in the diagram below. It is recommended that a silicone sealing compound is applied to the inner face of the
wall plate to provide a watertight installation.
(g) Fit the flue, see Sections 8.7 and 8.8.
NOTE:
When determining the flue length, measure the wall thickness from
the face of the outer wall plate.
(h) Slide the rope seal over the flue, until it touches the back of the heater, prior to removing the tape from the flue
foam sealing strip.
(I) Before installing the flue into the wall is necessary to provide a moisture barrier around the flue at the point which
will be in the centre of the cavity. Either of the following methods are acceptable: -
(i) Wrap a wire which will not cause corrosion tightly around the flue.
(ii) Form a bead of mastic or silicone around the flue.
9.0 COMBUSTIBLE WALL INSTALLATION
†
Note:
It is not necessary to allow for shrinkage of timber frames in existing buildings where the necessary length of
time has elapsed to allow for any contraction of the timber frame.
WALL LINER
OUTER WALL PLATE
FLUE SEAL
FLUE
INNER WALL
PLATE
ROPE SEAL
WHOLLY COMBUSTIBLE CONSTRUCTION
