Walls provide enclosure and structure for buildings. Nearly all buildings have walls that separate interior and exterior spaces and control access, daylight, ventilation, and temperature. Walls may support floors and roofs and brace other walls. There are two main types of walls in domestic English construction: masonry walls made of materials like brick, stone, or concrete blocks laid with mortar, and timber framed walls with a wood framework covered by other materials. Masonry walls are constructed using small units like bricks or larger units like blocks laid in mortar in a cellular pattern to provide strength. Cavity walls have an inner and outer leaf separated by a gap to prevent rain from penetrating the building.

1. Walls
Enclosure and structure

2. Nearly all buildings have walls

3. What to walls do?
• Provide enclosure
– Separation of interior from exterior
– Control of access
– Control of daylight and ventilation
– Temperature control
• Structure
– Walls may support floors and roofs as
well as themselves
– Walls can brace other walls

4. Types of walls
• Almost endless variations: timber,
glass, fabric, stone, mud…
• In domestic English construction two
types dominate
– Masonry
• Brick, stone or concrete blocks, bedded and
cemented with a mortar in a cellular structure
– Timber framed
• Softwood framework braced by sheet coverings
such as plywood or wafer board and protected
form the weather by an external barrier

5. Masonry walls
• Not just stone
• Principles of all
masonry
construction is
the same, small
units build up
large walls which
brace each other
at the corners
• Vertical joints
staggered for
strength.

6. Bricks and blocks
• The difference is in the size
– A brick is small enough to hold in one
hand whilst the mortar is laid with the
other
– A block is so big that two hands are
needed to place it, after the mortar is
laid
– Laying blocks is slower individually,
but a block is 6 times bigger than a
brick, so the wall goes up faster

7. Bricks and blocks
• Bricks are
usually clay and
used for facing
work
• Blocks are
usually concrete
and used for
hidden work
• The mortar is a
mixture of sand,
cement and
lime, to make it
soft and sticky

8. It’s all to do with size
65 x 102.5 x 215mm
Mortar joint 10mm
2 brick widths plus one joint = 215
3 brick heights plus 2 joints = 215

9. Blocks are bigger, but exact size is important
215 x 102.5 x 440mm
Mortar joint 10mm

10. Blocks are bigger, but exact size is important
215 x 102.5 x 440mm
Mortar joint 10mm
1 block equivalent in
size to 6 bricks laid in
mortar. Fast building

11. Bonding of brickwork
• Vertical joints are staggered for
strength
• Straight horizontal joints are not a
problem, friction keeps them
locked
Stretcher bond Header bond
English bond Flemish bond

12. Wall thickness can tell you a lot about construction
“9 inch” wall. Actually
215mm. Indicates solid, one
brick length construction.
Unusual in modern external
walls
“4 inch” wall. Actually
102.5mm. Indicates solid,
one brick width
construction. Used in
internal walls

13. The cavity wall
Brick outer leaf Block inner leaf
Outside Inside
50mm cavity

14. Cavity wall: the basic function is to keep rain out
We build cavity walls to
keep the rain out, not to
keep the house warm

15. Cavity wall: the basic function is to keep rain out
We build cavity walls to
keep the rain out, not to
keep the house warm

16. Cavity wall: the basic function is to keep rain out
Some rain gets through
the outer leaf, but it
trickles down inside the
cavity, on the wet, outer
side
We build cavity walls to
keep the rain out, not to
keep the house warm

17. Cavity walls: structural ties
A 250 cavity wall is
not as strong as a
215 solid wall. We
put cavity ties into
alternate courses to
strengthen it.
Drip to stop rain Stainless steel cavity ties
crossing

18. Keeping rising damp out
Floor
Fill
Ground

19. Keeping rising damp out
Damp proof course
DPC
Sheet plastic, lead,
modified
bituminous felt
Floor
Min 150mm
Fill
Ground

20. Keeping rising damp out
Damp proof course
DPC
Sheet plastic, lead,
modified
bituminous felt
Floor
Min 150mm
Fill
Ground
Damp proof membrane
The structure below DPC/DPM DPM
is always wet Sheet plastic, asphalt

21. Cavity walls in reality
DPC
DPC
Ventilation ducts

22. Wall stability: masonry wall fall over easily

23. Wall stability: masonry wall fall over easily

24. Wall stability: masonry wall fall over easily
The DPC is a particular weak line

25. Cross wall construction
Principle of the
buttress on gothic
churches

26. Cross wall construction
Principle of the
buttress on gothic
churches

27. Cross wall construction
Principle of the
buttress on gothic
churches

28. Cellular construction: the structural basis of masonry construction
A cellular structure resists forces from all directions

29. Insulating a cavity wall
Thick, insulating
block inner leaf

30. Insulating a cavity wall
Thick, insulating Fill the cavity with
block inner leaf insulation, risky

31. Insulating a cavity wall
Thick, insulating Fill the cavity with
block inner leaf insulation, risky

32. Insulating a cavity wall
Thick, insulating Fill the cavity with Internal insulating
block inner leaf insulation, risky lining

33. Masonry walls take all shapes and sizes