20
LT5674 (ISS 5)
TIMBER FRAMED DWELLING
This method allows for installation in timber frame buildings. Where removal of any part of the inner timber leaf of
the wall is involved the structural integrity of the wall must be maintained and the advice of your local Building
Control Department should be sought. If the property is under N.H.B.C. cover, it is advised that their advice should
also be sought. Reference should be made to the British Gas Publication DM2 "Guide For Gas Installations In Timber
Frame Housing" or GASA SAFE “Gas installations in Timber Frame Buildings” ISBN1-902632-30-3
Special attention must be paid to the location of the studwork frames of the inner leaf and the appliance positioned
accordingly. Electrical cables and pipe work that run within the inner timber leaf must also be located and taken into
account when positioning the appliance.
The following methods of installation may be adapted for use in timber frame buildings providing extra care is taken
to protect combustible materials from contact with hot surfaces.
Method 1 (For installation into a extended fire surround or false chimney breast)
An insulation material (20mm “Superlux” or equivalent) must protect all combustible surfaces (including plasterboard)
situated within the opening. A minimum clearance of 50mm must be allowed between the appliance case (rear, top and
sides) and the material used to line the opening. The base of the opening must be non-combustible.
Wrap the appliance body (top, rear and sides) and both flue tubes with “Rockwool” (50mm minimum thickness).
Where the duct pipes pass through the inner timber leaf concentric holes 200mm diameter should be cut around each duct
pipe, allowing a minimum 50mm air gap all round each duct pipe. A non-combustible sleeve 200mm diameter must be
fitted to these clearance holes.
To ensure that any condensation formed on the duct pipes does not drip on to the inner wall a length of galvanised wire
must wrapped around each flue pipe and secured in position by twisting the ends together. Ensure that the twisted ends
are located at the bottom of the pipes and the wire is centrally located within the cavity.
The vapour barrier on the back of the inner timber leaf should be carefully cut and fixed to prevent ingress of damp into the
plasterboard layer.
Method 2 (For installation into the inner timber leaf of the wall
Find a suitable position between the wall panel frames and carefully open up a hole (minimum dimension 555mm wide x
605mm x 230mm depth) this will ensure 50mm minimum clearance around the appliance body Note: the 230mm could be
reduced to 200mm if no combustible material is left between the back of the fire box and the outer skin on brickwork. Careful
attention must be made to securing the damp proof membrane back into position. (Note: To achieve the minimum depth
requirement it may be necessary to deepen the cavity by building up the wall surface with an appropriate none combustible
material.)
Line the exposed cavity (top, rear and sides) with an insulation material (20mm “Superlux” or equivalent) to form a boxed
chamber. The base of the opening must be non-combustible.
Wrap the appliance body (top, rear and sides) and both flue tubes with “Rockwool” (50mm minimum thickness).
Where the duct pipes pass through the inner timber leaf, concentric holes 200mm diameter should be cut around each flue
pipe, allowing a minimum 50mm air gap all round each flue pipe. A non-combustible sleeve 200mm diameter must be fitted
to these clearance holes.
To ensure that any condensation formed on the duct pipes does not drip on to the inner wall a length of galvanised wire must
wrapped around each flue pipe and secured in position by twisting the ends together. Ensure that the twisted ends are located
at the bottom of the pipes and the wire is centrally located within the cavity.
The vapour barrier on the back of the inner timber leaf should be carefully cut and fixed to prevent ingress of damp into the
plasterboard layer.
NOTE: Neither the appliance nor the “Rockwool” insulating pad may overhang the cavity space. Routing of the gas
supply must be carried out inline with the recommendations specified in the British Gas Publication DM2 ‘Guide for
gas installation in Timber Frame Housing.
