11
Brick, Stone Etc. Building. Main Case Recessed Into Wall
(Figure 8)
This installation has the fire box recessed into the inner wall of the building.
The front flanges of the fire box and the appliance metal decorative surround
will abut the front surface of the wall.
The non-combustible hearth must project at least 345mm in front of the
convection box front flanges and be at least 625mm wide (Figure 1).
The recess in the inner wall for the fire box should be to the size shown in
figure 1. The bottom of this recess should be at the same level as the top
surface of the hearth.
A lintel may be required above the recess for the fire box. If in doubt, seek expert
building advice before commencing to cut the recess.
Whenever a lintel is required to support the recess in the inner leaf of a
brick/blockwork building, follow the method outlined below. See figures 9
and 10.
1.The lintel should be either steel (Catnic) or reinforced precast concrete. It
should be 750mm long x 75mm deep x inner leaf thickness.
2. The opening should be, as near as possible, centrally
below a joint in the inner leaf block.
3. Cut out the opening for the lintel.
Where cutting through masonry, drill pilot holes and then
cut out the slot using a mechanical cutter. This will
minimise damage to the surrounding structure.
4. Insert the lintel. Bed the lintel on mortar.
Don’t dry bed.
Slate pin to ensure the lintel and structure above is secure
and safe
5.
Make the opening below the lintel by removing the
masonry and clearing debris. If the cavity has loose fill (e.g.
granular) insulation material, pack the edges of the opening
with Rockwool as you proceed to hold back the insulating
material.
The wall cavity must not be bridged other than by the flue
tube assembly. The fire box must not project into the
cavity between the inner and outer walls by more than 10mm.
See wall preparation for flue tube.
The cavity should be sealed where the opening has been cut. We
recommend filling fully across the cavity with Rockwool or
equivalent to at least 100mm all around the flue tube. Fill at the
bottom of the opening to the level of the hearth/fireplace floor. It
may be simplest to back fill the cavity with the insulation material
and then cut through the insulation to the size of the flue box hole.
Timber frame building. Firebox in front of wall
This installation is for use in timber framed buildings in
conjunction with a fire surround having a minimum depth
of 140mm (5 5/8in).
The non-combustible hearth must project at least 345mm
in front of the convection box flanges and be at least
625mm wide. For this type of installation the hearth must
be at least 50mm thick over its total area. (Figure 1).
Installation must be in accordance with the current edition
of Institute of Gas Engineers publication IGE/UP/7.
The back surface of the firebox and flue tube assembly
must be separated from the timber frame by 25mm of non-
combustible material. This can consist of the usual 13mm
plasterboard wall lining plus 12mm of “Superlux” or similar
non-combustible material. The opening should be between
studs.
Fig. 11 Flue pipe insulation
Figure 10
Figure 9
Fig. 8