A cavity wall consists of an inner and outer leaf separated by a cavity. Cavity walls were introduced to prevent dampness penetration into buildings. The walls are strengthened through the use of wall ties that connect the two leaves and are made of galvanized steel. Problems can occur if mortar droppings gather in the cavity, allowing water to pass through. Ensuring a clean cavity through the use of mortar traps and brushing helps prevent dampness penetration.

1. Cavity Walls
Construct Cavity Walling

2. Student Copy
Name ………………………………...

3. What is a cavity wall?
A cavity wall is made
up from:
•
•
•
Cavity wall construction
50mm minimum width of air gap
Section through a cavity wall

4. Solid Walls can let dampness
into buildings.
Section through a solid wall

5. Why do we use cavity walling?
Cavity Walls were
originally
introduced to
prevent ________
penetration.
Section through a cavity wall

6. Problems?
• Weakness: Two slender half brick / block
skins are not as _______ as a one brick thick
solid wall.
How can this Kind of walling be
strengthened?
The use of ______
______ Ties

7. _______ ______ Ties
The walls are supported and tied into one
another by means of specially designed
metal ties called ‘_______ ties’.
Wall Ties are made from __________ steel

8. Cavity Wall Ties
Problems can occur when bridging the cavity, such
as _______ penetrating from the outer leaf to the
inner leaf.
Section through a cavity wall

9. Common Faults

10. Wall tie spacing’s
Building Regs state wall ties must be positioned
_____mm vertical ______mm horizontal (100mm
cavity) and no more than 300mm vertically on
un-bonded reveals.

12. Bridging the cavity can create
problems.
Preventing ______
Transfer.
The ______ DPC
prevents water
crossing along the
top of the air-brick
liner.
Section through a cavity wall

13. Typical components needed for
bridging cavities at openings.

14. Keep the cavity clean.
Mortar droppings
can gather on wall
ties and at the
bottom of the cavity
creating a ________
for water to pass
through to the inner
leaf. Section through a cavity wall

15. Clean
Cavities
Keep the cavity
clean to
prevent ______
penetration
Section through a cavity wall

16. Ensuring Cleanliness
• _______ Hole

17. Ensuring Cleanliness
• _________ _________

18. Wall construction below ground
level
Cavity walling below ground level:-
• Cavity wall formed with two leafs of
common bricks. The external leaf will revert
to facing bricks __ course below ground level
to allow the bricklayer to ensure that bond is
worked out

19. Broken Bond
If Broken Bond can not be avoided the piece should
be placed in the centre of the wall, or against the
reveal.
No cut should be less than __ _______
If bastard sized window and doors are used then the
piece is better placed _________ the opening if
possible.
ANY CUT SHOULD ALWAYS STAY IN THE SAME
POSITION