2. Main functions of walls
1. Strength
2. Stability
3. Weather exclusion
4. Thermal Insulation
5. Sound Insulation
6. Durability
7. Fire resistance
8. Appearance
3. CAVITY WALL:
• Cavity walls consist of two
'skins' separated by a
hollow space.
• The skins are commonly
masonry such as brick or
concrete block.
• Masonry is an absorbent
material, and therefore will
slowly draw rainwater or
even humidity into the wall.
• The cavity serves as a way
to drain this water back out
through weep holes at the
base of the wall system or
above windows
4. CAVITY WALL INSULATORS :
• Cavity wall insulation is used to reduce heat loss through a
cavity wall by filling the air space with material that inhibits
heat transfer. The internal and external leaves should have at
least 10cm thickness
• The three most common types of cavity wall insulation used
are:
• Blown mineral fibre.
• Polystyrene beads or granules.
• Urea formaldehyde foam.
• Lean concrete
5.
6. CAVITY WALL INSULATORS :
• The Government regards cavity wall insulation
as one of the most effective energy saving
measures that you can carry out to your home
and as well as saving you money it helps
reduce emissions of carbon dioxide, the main
greenhouse gas causing climate change.
• This is because up to 35% of the heat loss
from your property is through the walls.
7. Return corner of a cavity wall in stretcher bond including wall
ties and DPC
8.
9. WALL TIES :
• Wall ties ensure that the wall leafs do not partWall ties ensure that the wall leafs do not part
away from each other, effectively splitting theaway from each other, effectively splitting the
two leaves. The normal spacing of the ties istwo leaves. The normal spacing of the ties is
laid down in the Building Regulations.laid down in the Building Regulations.
10. Wall Ties
There are a large variety of different
types of wall ties, but they all have
two basic requirements of:-
1 .Tieing the outer and inner leaf of
the cavity wall together.
2 .Prevent moisture passing from
the outer to the inner skin of
brickwork.
12. • The maximum horizontal spacing of wall ties is 900mm and
maximum vertical spacing is 450mm. The wall ties are
provided in such a way that they do not carry any moisture
from outer leaf to inner leaf. Different shapes of wall ties are
shown in below figure.
15. • Weep holes are typically found in the outer masonry
leaf of cavity walls, just above the flashing with an
interval of 1 m. They can also be found above
windows, doors or other penetrations. They should
be provided at regular intervals so as to allow any
moisture collected by cavity trays to escape.
• A flashing material in cavity wall construction needs
to act as a means to moisture collection, and then
more importantly to the diversion of it. Copper
flashings exceed synthetics in puncture and tear
resistance as well, assuring a stout collection area for
any moisture pooling within the wall cavity.
18. Advantages of Cavity walls.Advantages of Cavity walls.
• The moisture cannot enter from outer wall toThe moisture cannot enter from outer wall to
inner wall , since there is no direct contact.inner wall , since there is no direct contact.
• Provide good insulation against sound.Provide good insulation against sound.
• Protection against efflorescence.Protection against efflorescence.
• Proves economical during construction.Proves economical during construction.
• Load on the foundation is reduced.Load on the foundation is reduced.
• Reduction of heat transfer ,since air layerReduction of heat transfer ,since air layer
between leaves acts as non-conductor of heat.between leaves acts as non-conductor of heat.
