FLOOR CONSTRUCTION BY T ZOWA

• The function of any floor is to provide a level surface which is capable

• No material should be used as hard-core which contains water soluble

Solid concrete ground floor

Consists of four main components

Hard-core,Blinding,Concrete slab or bed and Membrane

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Hardcore
•Provides firm base on which the concrete slab is laid and helps to spread
any point loads over a great area
•It also prevents moisture from progressing from the sub-base by acting
against capillary action
•The hard-core is laid in 150mm-150mm areas, to the required depth and
each layer has to be roller compact
•The materials in which to use include construction gravel and coal ash.
•No material should be used as hard-core which contain water soluble
sulphates or harmful material which are liable to cause damage to any part
of the floor.

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Blinding
•Prevents the damp proof membrane from being damaged by the hard-core and also
provides a true surface on which reinforcement can be conditioned
•The blinding should be fit to 50-75mm and can be made of weak concrete
•The membrane provides the barrier to the passage of water from the ground into the
structure.
•It can be placed above or below a concrete slab
•When placed below, it prevents the leakage of the cement metrics into hard-core and
also keeps the concrete bed dry
•The building regulations require that the floor should be constructed to prevent
moisture movement and also to protect any part of the floor from being affected by
any moisture or any deleterious material.

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Concrete slab
•Made of reinforced concrete or plain concrete
•For plain concrete the thickness should be between 100-150mm and for a
reinforced concrete slab, it should be at least 150mm thick
Advantages of the floor
•It is completely damp proof
•Has good fire resistance properties
•Is cheap to construct on the level ground
•Heat levels can be reduced to acceptable levels.

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Disadvantages of the floor
•A break in the damp proof membrane will allow moisture penetration
•It is expensive to construct on sloping ground
•It has no facilities for under floor storage
Services may be difficult to alter or maintain

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Suspended timber ground floor
•The regulations require that the ground surface should be covered with a layer
of concrete not less than 100m thick, which should be properly laid on a hard-
core free from any matter which may cause damage to the concrete slab
•There must be space above the upper surface of the concrete slab of not less
than 75mm to the underside of any wall plate and not less than 125mm to the
underside of suspended timbers

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• The space must be clear of any debris and must have adequate ventilation
• A damp proof course should be placed so as to ensure that moisture from
the ground cannot reach any timber or any other materials which an be
adversely affected by it.
• Ventilation is provided on by the air bricks on wall and is essential in order
to keep moisture content of the timber floor members below 20%
• Above this level fungal growth may take place which cause the weakening
of the timber members
• The floor consists of timber boards which should be kept 13mm away from
the surrounding walls to avoid the risk of damp penetration and allow the
floor to expand and contract and also flex the out gravity against the wall

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Junction of solid and suspended floors
•It is important to provide ventilation beneath a suspended timber floor, and
where such a floor meets a solid floor, pipes should be laid beneath the solid
floor connecting with air bricks.
•The damp proof membrane should be linked with the dpc in the cross wall
by a vertical dpc.
Disadvantages of the floor
•It is expensive to construct on a level ground due to high cost of timber
•Floor is liable to dry rot, if ventilation if poor.
•It loses heat easily – insulation is required to overcome the heat loss
•The construction is noisy and smelly

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Upper floor construction
•Timber being a combustible material is restricted to the construction
of small domestic buildings
•The timber joints are supported by the walls or by use of metal fixes
•The joints must have an economic span of between 3.5 and 4.5m
for spans over this, the double floor is used
•Support from internal walls can be easily supported by joist hangers
or by direct bearing.
•The joists have to be prevented from twisting which occurs due to
shrinkages by a process known as strutting. Three types of strutting can be
used Inline, Staggered and herringbone Strutting

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Openings are created on the floor by a process known as trimming

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 Common joists – spans from support to support
Trimming joists – spans in the same direction as. The common joists as also
used to support the trimmer joists.
•It is usually 25mm thicker than the common joists.
Trimmer joist – is at right angles to the main span supporting the trimmed
joists and should be of the same size as the trimming joist
Trimmed joist – are cut to make way for the opening and are of the same
size as the common joist but they are support by the trimmer joist and the
load bearing wall

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Precast concrete floors
•Suspended close precast concrete slabs are generally considered to light to
medium load bearing buildings where loading span in one direction.
•The systems available can be considered as precast hollow floor or as
composite floors available in a variety of sectioning such as
Box sections
T-sections
Channel sections

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 Precast hollow floors

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Advantages
•Factory manufactured therefore well inspected under factory conditions
•Faster construction due to read-made units
•Lighter than solid construction

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Channel section

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Advantages
•The voids can house services
•Can be covered by suspended ceiling
•Compared to box sections they have 50% reduction in concrete volume
•Faster construction
•Factory manufactured
Composite
•Composite floors are a combination of precast units and in situ concrete

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Comparing hollow sections with in situ concrete the following can be achieved
•50% reduction in volume of concrete
•25% reduction in weight of reinforcement
•10% reduction in size of foundation
•Hollow sections give a flat soffit which can be left in natural state or can be
plastered
•The voids can be used to house services
•Ribbed soffits of channel T-units can be covered by suspended ceilings

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 Floor finishes
•Timber finishes
•Applied
•Joint less/in situ

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 Types of floor finish depend on the following

• Type of base
• Room usage
• Degree of comfort required
• Maintenance of the floor
• Cost
• Appearance
• Safety requirements and individual preference

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• The finishes are considered as either timber finishes or applied or Jointless
finishes
• Timber finishes are supplied as boards, sheets or blocks made of softwood
or hardwood
• The boards and sheets are joined together along the edges by tongue and
groove joints are fixed to the joists by nails
• Blocks are supplied in small pieces and are fixed to the base by using an
adhesive

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Different patterns can be achieved such as herringbone pattern

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• Applied floor finishes are supplied in tile or sheet form
• The sheets cover all the material which arrives on site in a role of
predetermined width and a variable length
• These may cover the rooms in one piece or may be a few joints
• Tiles are delivered in pieces which all have the dimensions fixed
Examples
Rubber tiles
PVC tiles
Carpets

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• Jointless are applied to the floor in a fluid state and are allowed to set
forming a hard jointing surface
• These finishes are cement based such as screed and granolithic finish
• Mastic asphalt can also be used as a Jointless finish

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END OF FLOOR CONSTRUCTION PRESENTATION by Zowa T

THANK YOU

SAYONARA

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