Superstructure design

College of North West London presentation; for the National Diploma in Construction

1. SUPERSTRUCTURE
DESIGN
BTEC
UNIT 6
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2. DESCRIPTION OF THE
SUPERSTRUCTURE
THIS INCLUDES;
WALLS
FLOORS
ROOFS
DOORS & WINDOWS TO KEEP
BUILDING WATERTIGHT
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3. WALLS
Most external walls are built by brick
and block.
Each can be defined as either high or
low density classification.
This information is obtained from the
UK National Annex
It also provides specification guidance
on other aspects such as;
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4. Specification Criteria for Bricks/
Blocks
Dimensions and Tolerance
Configuration and format
Density
Compressive Strength
Freeze/thaw resistance
Active soluble salts content
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5. Specification Criteria for
Brick/Blocks
Durability designations
Water absorption
Reaction to fire
Bond strength
Clay engineering and DPC bricks
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6. Concrete Blocks
Been used since the 1930’s
Made from aggregates such as breeze and
clinker
Used mainly on the internal skin of cavity
construction
Blocks also used for internal load bearing
walls and partitions
Internal block walls will be finished with
plasterboard and a skim finish
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7. Cavity Construction
Most domestic dwellings are
constructed in cavity construction
Complies with building regs.
Offers adequate resistance to the
passage of heat energy.
Legislation ensures new buildings are
energy efficient with added insulation
and sustainable building products.
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8. Cavity Construction
Cavities reduces excessive moisture from
entering the property
2 ‘skins’ of wall connected with stainless steel
wall ties-450mm vertically- 900mm
horizontally
Damp proof course used to prevent moisture
from entering property
D.p.c laid at a min. of 150mm above ground
level
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9. Cavity Construction
There are 3 different types of cavities.
Clear cavity- 102mm brickwork, 50mm cavity,
100mm aerated block work & 40mm thermal
board
Filled cavity-102mm b/w, 75mm cavity batt,
100mm aerated block with plaster
finish
Partial cavity- 102mm b/w, 50mm cavity,
50mm insulation, 100mm aerated block with
plaster finish
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10. Types of Cavities
Clear cavity
 Partial Fill
Fully fill
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11. Structural Stability
In modern housing the stability of an
external wall is assisted by the bonding
in of the flank & partition walls.
Additional stability is provided by the
floor joists and the walls.
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12. Sound Insulation
Building regs set the minimum
thickness for party walls.
For solid walls 215mm is the min width.
For cavity construction 250mm is the
minimum width.
Materials must be of high density
Elevates airborne sound-voices, radio
etc
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13. Fire Protection
Building regs demand external walls of
a 2 storey dwelling to have 30 minutes
of fire resistance and the party wall to
have 1 hour.
This enables any occupants to escape
the fire within the time period.
Level of fire protection is achieved by
the use of clay bricks & concrete
blocks.
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14. Thermal movement
In an average year a wall will expand &
contract due to heat, cold & moisture
content.
Movement in the building must be allowed to
occur, otherwise cracking will appear.
Expansion joints should be included on long
runs of brick/block work eg 12m for b/w &
7m for block work
A compressible filler with a flexible mastic
sealant is used for exp joints.
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15. Parapet Walls
This is the section of wall which
extends beyond the height of the roof
‘Throated’ coping stones are bedded
onto the top of the wall with a dpc to
prevent water ingress
A cavity tray should also be inserted in
case moisture penetrates through the
b/w.
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