1. Building Construction I Sofia Sebastian 1
Floors
Building Construction I Sofia Sebastian

2. Building Construction I Sofia Sebastian 2
Floors
Functions of Floors
To support the load from finishes, people, machines, furniture and fixtures
To provide a level surface for normal uses in a building
To provide level surface for any floor finishes that are applied
Classification of Floors
Ground floors
Upper floors
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Ground Floors
Over site concrete slabs - Concrete slabs on the ground on hard core beds
Upper Floors
Reinforced Concrete slabs
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Construction of ground floor slab
A hard core bed
A blinding
A damp proof membrane
Building Construction I Sofia Sebastian

5. Building Construction I Sofia Sebastian 5
Hard Core Bed - Function
Provide a free draining bed to make the concrete slab warm and dry
Resist the growth of vegetation
Provide a level base for the over site concrete
Construction of ground floor slab
A hard core bed
A blinding
A damp proof membrane
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Hard Core Bed
The hard core bed consists of material that resists crushing such as broken brick, stone or rock.
Pieces should be large enough to ensure plenty of space so that moisture isn’t trapped within the hard core.
15-20 cm thick
Flatten by hand or by rammer or by plate vibrator
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The blinding – Function
The finished hard core has a rough surface that you must make smooth before laying the dpm
2. Laying of 50mm of sand, ashes or weak concrete slurry over the surface of the hardcore is called blinding
3. Level the surface and inspect it to see that there are no sharp projections
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Damp proof membrane in floors
Prevent dampness entering the building through the concrete slab
A heavy duty polythene sheet tough enough to be handled on a building site without tearing or puncturing
Lay the dpm so that the edges of dpm overlap the joints
The edges of the dpm must also overlap the edges in dpc
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9. Building Construction I Sofia Sebastian 9
Laying an oversite concrete slab
made from concrete mixed in these proportions
100 mm deep
1 part cement
3 parts sand
6 parts water
Since concrete shrinks as it dries, you should not lay it in areas that are larger than 3m x 3m.
Pour the concrete in a checker board pattern so that you can fill in the spaces left after shrinkage as each section dries
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10. Concrete first floor slab types based on structure
1. One-Way Slab
A one-way slab is uniformly thick,
reinforced in one direction, with parallel supporting beams.
Suitable for light to moderate loads over relatively short spans of (1.8 to 5.5 m)
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11. Concrete first floor slab types based on structure
2. One-Way Joist Slab
A joist or ribbed slab is cast integrally with a series of closely spaced joists, which in turn are supported by 2 beams
Designed as a series of T-beams, joist slabs are more suitable for longer spans and heavier loads than one-way slabs.
Suitable for light to medium live loads over spans of (4 to 10 m)
Building Construction I Sofia Sebastian

12. Concrete first floor slab types based on structure
3. Two-Way Slab and Beam
A two-way slab of uniform thickness may be reinforced in two directions and cast integrally with supporting beams and columns on all four sides of square or nearly square bays.
100 minimum slab depth.
suitable for carrying intermediate to heavy loads over (4.6 to 12 m) spans.
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13. Concrete first floor slab types based on structure
4. Two-Way Waffle Slab
A waffle slab is a two-way concrete slab reinforced by ribs in two directions.
Waffle slabs are able to carry heavier loads and span longer distances than flat slabs.
Suitable for spans of (7 to 16 m)
(125 or 150mm) rib width
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14. First floor slab types based on materials
Reinforced first floor construction
Most reinforced concrete suspended floors are cast in situ
Two forms of construction are possible
A solid concrete slab with
main reinforcement that spans the shorter distance and
secondary reinforcement
that spans the longer distance
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15. First floor slab types based on materials
Reinforced first floor construction
Mixing and pouring the concrete– A typical mix for a reinforced slab is 1:2:4
One part cement, two parts sand and four parts coarse aggregate
The water cement ratio should be 0.5
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16. First floor slab types based on materials
A beam and block floor
with beams that span the shorter distance only
Beam and Block Floor
Inverted ‘T' shaped concrete beams span from wall to wall.
These walls must be founded.
The beams are infilled with concrete blocks to provide a stable suspended floor, which can often support internal partition block walling.
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