This document discusses the key components of building superstructures, including external walls, floors, roofs, and windows. It focuses on walls, describing that most external walls are made of brick and concrete blocks. It provides specifications for bricks and blocks, and notes that cavity construction is most common, using two wall skins connected by ties to improve structural stability, sound insulation, fire protection, and allow for thermal movement.

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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