Granite

Granite
Stringer
Riser Board
There are three systems in which you can put a top
layer of a floor onto a concrete base:

Bonded

Monolithic

Unbonded
Bonded Floor
Floor Screed
Sand & cement
Grout
Monolithic floors are laid within 3 hours of
the base.
Monolithic Floor
Monolithic floors may be laid at a
minimum thickness of 20 mm.
1
Unbonded Floor
An unbonded floor is where no bond to the concrete
base is possible owing to its condition. Minimum thickness is 50mm.
2
Granolithic is a concrete product, composed of cement and
fine aggregate, the aggregate being granite chippings,
which will give the hard wearing surface finish.
The materials used in granolithic work
include granite chippings 6 mm to dust,
and Ordinary Portland Cement.
Granite chippings and cement are
mixed by volume in the ratio of
5 parts granite to 2 parts Ordinary
Portland Cement.
The preparation of a separate construction granolithic floor includes
hacking, cleaning, soaking with water, and grouting just before laying.
3
Problems that might arise with floor screeding
CAUSE
EFFECT
Poor preparation of sub-base
Cracking and lack of bond
Mix too dry
Hard to lay gives weak finish
Too much cement
Shrinkage cracks
Too little cement
Will break down when load
applied
Too much water
Hard to form flat surface; may
shrink and be weak
Could leave pockets of sand
with no cement, or vice versa
Brings water to the surface
with cement, which is known
as laitance
Weakens surface
Poor material mix
Over-trowelling/trowelling too
soon
Poor curing
The floor should be allowed to
dry as slowly as possible
The recommended area of separate construction flooring that can be laid without
an Expansion strip is 14 square metres.
4
Setting out the risers and treads - a storey rod is used.
The height of the top riser and bottom are marked using a storey
rod, a chalk line is then snapped between the two. This is known as
Storey Rod
Nosing Line
Riser
Tread
The remaining risers are set to the nosing line and
levelled across the tread using the storey rod.
5
Laying a granolithic staircase
Total going equals the proposed length of travel.
Total rise equals the distance travelled from the floor.
Total going
Total
Rise
Treads and risers are in the ratio of 2:1.
Treads and risers are in the ratio of 2:1.
i.e. for every inch you rise you tread 2 inches.
a riser of 6” = a tread of 12”.
6
Laying a granolithic staircase
Fixing riser boards
The beveled edge at the
bottom of the riser allows
the tread to be laid
Stringer
Riser Board
How to set out steps
Using the nosing line fix the riser boards and stringer, and wedge into
place.
Making a granite mix of 5 parts granite to 2 parts Ordinary Portland Cement
start laying the steps, working on alternative steps.
7
The cove is formed as part of the skirting in the angle between
the wall and the floor.
Timber grounds
Coving trowel
In order to form the cove timber grounds are fixed to the
wall surface and the floor surface
This will allow the coving trowel to run along them, at
the same time forming the cove in the angle of the floor
to the wall
The main reason for a cove in the skirting is to prevent bacteria lodging; it
is much easier to clean and is mainly seen in Hospitals
Granolithic coves are finished using a coving trowel on timber ground.
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