Obvious areas of
possible leakage
Blockwork
All blockwork leaks, from 0.1 to 60 m3/h/m2. Plastered
blockwork does not leak, however any area that is not
plastered is a potential problem i.e. above false
ceilings and below raised floors. Painting good quality
blockwork reduces leakage, but painting poor quality
blockwork has little effect.
Pipework and electrical services
Pipework and electrical penetrations through the
envelope into plantrooms, electrical switch rooms all
should be sealed, as collectively they can add up to a
large area of leakage.
Beams and steelwork
Steelwork encased in fire cladding and hallow concrete
beams. If they are not sealed properly, then sealing
after construction could prove either futile or at the
very least expensive.
Ceilings
All types of ceilings are a potential area of leakage
due to light fittings.
Curtain walling systems
All joints are weak points, especially where it abuts
the floors, walls and roof sections.
Dry Lining systems
Dry lining systems should be sealed with a continuous
bead of plaster along the length of the bottom of the
board. All penetrations should be sealed. Where these
systems join the external walls extra care must be taken
to ensure that there are no leakage paths.
Lift shafts
Lift doors should have adequate seals. Special attention
must be made to any raised floors adjacent to the lift.
The vent at the top of the shaft should not be sealed
for the test.
Profiled metal decking
The underside of profiled metal decking and all joints
will require effective sealing during the laying of the
sheets. Perforated liner sheets and relying on the
vapour barrier should be avoided as they under perform.
Windows and door frames
Windows and doorframes need to be sealed to the inside
surface of the envelope. Any cavities must be sealed
before final finishes are made.
Wall to ceiling and roof joints
All walls to ceiling and roof joints need to be sealed
properly at the time of construction, as these areas are
the hardest to reach and not easily inspected after
construction. All expansion joints between concrete
beams and blockwork should be deep filled with an
airtight compound.
Riser shafts
Riser shafts need to be very tightly air sealed to
prevent leakage into plantrooms and the building cavity.
Steelwork penetrations
Steelwork penetrations that pass through the internal
surface must be sealed with a compound that will allow
for expansion and contraction.
Loading bay doors
Loading bay doors should preferably be of the panel
tight with adequate seals.
Roller Shutter Doors
BS EN 12426 classifies the air permeability of doors.
The seven Classes run from 0 – 6. The higher the class,
the lower permeability. A Class 1 door has a
permeability of 24m³/m²h at 50 Pa. Each class has a
permeability rate half that of the previous Class.
Water and condensate traps.
Water and condensate traps should be filled at the time
of the test.
Materials that must be avoided when sealing any joints.
Mineral wool, Rockwool
These material do not provide and adequate seal as the
are pervious to air..
Tape and expanding foam.
The life span of tape and expanding foam is too short
for the use in a building that would be standing for
many years. Only foam designed for air sealing should be
used.
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