Floor finishes

1. Insitu floor finishes : mixed on site, laid in a fluid state and allowed to set and dry to
form a joint less surface

Examples

- Mastic asphalt
- Pitch mastic
- Granolithic
- Magnesium ox-chloride
2. Applied floor finishes: finishes supplied in tile or sheet form and are laid onto asuitably
prepared base

Examples

- Flexible PVC tiles and sheet

- Thermoplastic tiles
- Rubber tiles and sheet
- Carpet
- Linoleum
- Cark tiles sand and carpet
- Quarry tiles
- Plain clay floor tiles
3. Timber floor finish: boards, sheets and block of timber attached to a suitable structural
frame or base

Examples

- Timber boards
- Timber strips
- Timber sheet
- Wood blocks
 - Parquet
Ref: chudley vol I page 174

External rendering

Mixes: sand / cement or cement / lime / sand

Terms

Grazing: net work of small hair line crack

- caused by excessive trowelling

Laitance: scum / layer of rich cement / sand

- Formed as a result of over-trowelling

Workability: ability of mix to flow

- Necessitated by limes, admixtures

Background suction: the sucking of water by the background from the mix

Under coat

- Normally between 10 to 15mm thick

- It’s stracted or combed before hardening
- Mix proportions 1 : 3 – cement sand
2: 1: 8 – 9
1: 1: 5 – 6 cement / lime / sand
1: 2: 8 – 9
1: 2 – 3 hydraulic lime

Final coat

- It’s less than 5 – 7mm thick

- Not stronger than preceding coat
Finishes

1. Floated finish : rough plastering

2. Textured or combed finish : funny figurers on wall
3. Floated textured finish : trowel with marks
4. Scraped finish
5. Brushed finish : wire brush patterns
6. Pebbledash (dry dash) : small stones squeezed on finished wall
7. Rough cast (wet dash) : mixed with mix and grid
8. Tyrolean
Ref: Barry vol 1

INTERNAL PLASTERING

Functions

1. Hide irregularities
2. Provide a face for decoration
3. Resist damage by impact

Lime plasters

Disadvantages

- Drying shrinkage – causing cracking

- Slow drying
- Require several coats (expensive)

Gypsum

Crystalline combination of calcium sulphate and water

Process: crush – screen – heat to dehydrate

Class A: plaster of Paris - heated at 170ºc - ¾ water removes

Class B: retarded hemihydrates gypsum - plaster

Class C: anhydrous gypsum – nearly all water removed

Class D: keen’s plaster

Dry lining techniques

Finishing external, internal walls or partitions with variety of materials ready for direct
decoration

Advantages

- Thermal insulation
- Faster in drying
- Speed in erection
- No water used
- Sound insulation

Material used

- Plaster boards
- Asbestos sheets
- Plywood
- Chip board
- Hard board

Plaster boards

Aerated gypsum core encased and bonded with paper liners

Types inside (ivory colour direct decoration) fixed using nails / plugs

\ gypsum

Wall board - Lath

Outside paper (grey colored skin coat)
- Base board - Plank
EXTERNAL RENDERING

Definition: it is a surface application of cement: sand or similar mix to an external wall either to
give it a good appearance or make it weather resistant or both. It may comprise one, two or three
coats. The first is termed first or render coat. The second floating coat and the last is called the
final or finishing coat

Terms

Crazing
: it is a network of fine hair cracks at the surface formed by excessive trowelling and
smoothing of the rendered surface

Laitance: it is the accumulation of a skin or layer of rich cement mortar of high water content at
the surface caused by excessive trowelling

Workability: the ability of the mix to flow with ease during handling. The material incorporated
to increase workability instead of cement is

- Hydraulic limes
- High calcium lime mixtures

Background suction

The mix should have water retentivity to allow hydration of the cement. Retentivity is increased
by adding lime. In order to achieve retentivity the background suction is reduced by a
preliminary damping of the surface, but no visible water film or droplets should be present at the
surface when the rendering is applied to increase bond

Achievement of a god bond is done by the following

1. The raking out by mortar joints to about 10mm depth

2. Hacking the surface to provide mechanical key
3. The application of a preliminary spatter dash treatment
Undercoat

An undercoat is normally between 10mm and15mm thick. It is combed or scratched before

hardening to provide a key for the subsequent coat. On very irregular background the first
undercoat does not provide a sufficiently good surface to receive the final coat directly hence a
second undercoat (10 – 13mm thick) may be applied. Mix proportions – (1:3, 2:1:8-9, 1:1:5-6,
1:2:8-9, 1:2-3 hydraulic lime)

Final coat

It is less than (5 – 7mm thick). It should not be stronger than the preceding coat, except where
coarse aggregate is included

Finishes

1. Floated finish 5. Brushed finish

2. Textured or combed finish 6. Pebbled dash (dry dash)
3. Floated textured finish 7. Rough cast (wet dash)
4. Scraped finish 8. Tyrolean

INTERNAL PLASTERING

Functions of plaster

1. Camouflage irregularities in the backing wall

2. Provide a continuous surface which is suitable for direct decoration
3. Be sufficiently hard to resist damage by impact upon its surface

Gypsum plaster fulfill these requirements but lime plaster do not due to the following
disadvantages

1. Drying shrinkage which causes cracking

2. Slow drying out process which can take several weeks causing delay for other trades
3. Need to apply
4. lime plaster in several in several coats to reduce the amount of shrinkage
Gypsum

It is a crystalline combination of calcium sulphate and water. After crushing and screening the
gypsum is heated to dehydrate the material. The amount of water remaining at the end of this
process defines its class

Class A: plaster of Paris - ¾ of water removed - 170ºc heating

Class B: retarded he- midrate gypsum plaster

Class C: anhydrous gypsum plaster – nearly all water removed

Class D: Keene’s plaster

The choice of plaster mix, type and number of coat will depend uporn the background to which
the plan in to be applied

Advantages

1. Speed of erection
2. Reduction in the amount of water used during construction
3. Reduction in drying out period
4. Increased thermal insulation

Materials

a. Hardboard
b. Plywood
c. Chipboard
d. Plasterboard

Fixed to timber batterns attached to the wall. Finishing can be a direct application of paint,
vanish or wall paper
PAINTS

Definition: painting is the application of a thin coating of material in a liquid or plastic condition
to a surface as a decorative or protective measure, normally made to harden to a solid film. Its
chemical and physical properties depend on:

i) Nature of the surface being coated

ii) Method of application
iii) Basic requirements

Materials: paints, vanishes, stains, preservatives etc

Paint composition

Consists of one or more solid materials

1. Pigments
2. Vehicle (a liquid)

Pigments: present in power form and suspended in vehicle made from metallic oxides and salts

Functions

i. provide the hiding power and colour of the paint film

ii. Give corrosion resistance to the surface painted

Paint vehicle: is the liquid part of paint

Functions

i. Facilitates application by giving the paint mobility

ii. Serves as a binder for the pigment on drying
iii. Gives adhesion to the surface painted

Paint vehicle is a volatile solvent (a liquid which dissolves a substance but which readily
evaporates leaving behind the dissolved substance unaltered chemically) e.g. alcohols,
methylated spirits, naphtha’s and coal tar derivatives plus organic chemicals.
Paint types

1. Emulsion paints: this is a synthetic resin (PVA) emulsified in water. Other ingredients
are usually stabilized which prevent coagulation (becoming thick). Their drying action is
due to evaporation of the emulsifying liquid
Advantages
i. Their paint films are initially and sometimes permanently permeable
ii. Their hardened films are washable
iii. Are alkaline resistant hence may be used on cement, concrete, asbestos – cement
and plaster
iv. Suited to rolled and brush application
2. Water paints: composed of drying oil, oil vanish or synthetic resin emulsified in water
together with a stabilizer as glue or casein. They contain pigments and the final product is
supplied in the paste from mixed with water. Used mainly for interior decoration
Advantages
i. They give a permeable paint film washable when hard
ii. Most are unaffected by alkalis
3. Distempers (i.e. white wash): distempers do not contain a dry oil, oil vanish or resin and
they are not emulsified. They consist of a pigment and extender with a water-soluble
binder such as glue size and are supplied either in the mixed powder form or a paste in
water. Prepared for use by adding water. Used on ceilings and as a temporary decoration
for new walls.
Disadvantages
They are non-washable and easily rubbed off.

Other paints include

a. Solvent type paints

b. Oil paints
c. Hard gloss paints
d. Enamel paints
e. Synthetic resin paints
PAINT SCHEMES

1. Primer
Functions
- It gives protection against corrosion of metals or against dampness especially of site-
stored joinery
- Used to adjust the suction of a surface and provide good adhesion for subsequent
coats
- Acts as a barrier coat to isolate one coat from a preceding coat – prevent chemical
interaction e.g. - red lead – used on iron and steel
Calcium plum bate – for zinc and galvanized iron
Zinc chromate – for aluminum
Red oxide – protects ferrous metal
2. Undercoat paints
Functions
- To obliterate the background and provide a uniformly dense tone (colour) to assist the
finish
- Provide good adhesion for the finishing coat
3. Finishing paints
Functions
- Give the required reflection characteristics to the surface
- Give the final colour
- As an exterior paint, seal the surface against the weather
- Offer elastic quality to the surface

Defects in paint film

a. Crazing or cracking: deterioration due to weathering or a symptom of unsuitable paint

formation, adulteration or subsequent maltreatment
b. Chalking: powdering of paint film due to normal weathering causing breakdown of the
binder
 c. Bleeding: the softening of a paint film due to an agency such as resinous or bituminous
matter acting as a solvent on the binder and penetrating the film causing staining and
local breakdown
d. Sulphiding : discoloration of certain paint films due to conversion of compounds present
to the sulphide (change of colour)

Floor finishes (const tech vol I)

The type of floor finish to be applied to a floor will depend upon a number of factors

i. Type of base
ii. Room usage
iii. Degree of comfort required
iv. Maintenance problems
v. Cost
vi. Appearance
vii. Safety
viii. Individual preference

Types

1. Cement sand screed

This serves a number of purposes
i. Provide a smooth surface
ii. Provide falls for drainage
iii. Provide thermal insulation
iv. Accommodate service pipes and cables
- Cement and sand screeds in the ratio of 1 : 3 by weight are suitable for thickness up to
40mm
- The screed is laid on the insitu concrete base before it has set (within 3 hours of
placing).
 - Complete bonding is obtained and the thickness need only to be 12mm. this is called
monolithic construction
- With separate construction, the base has to be hatched, cleaned and dampened. In this
respect the screed has to be 40mm
- Where the screed is laid on a DPM it is classified as un-bonded and should have a
minimum of 50mm thick
- Screed laid on a comprehensible thermal insulation is called floating and should be at
least 65mm thick
2. Granolithic
- This is a mixture of Portland cement and granite chippings. Applied to a sub-floor
- A typical mix for granolithic is 1 : 1 : 2 cement, sand and chippings by volume
- Finish obtained is very hard wearing, noisy and cold to touch
- Used mainly in situations where easy maintenance and durability are paramount such
as common entrance hall
- Its applied to green concrete sub-floor as a topping in a single layer 20mm thick in
bay size not exceeding 28m² resulting to monolithic floor and finish construction
- For mature concrete, it needs to be hacked and brushed well to remove all the laitance
before lying. The finish at least 40mm thick should be laid on a wet cement slurry
coating to improve the bond in bay sizes not exceeding 14m²
3. Wood blocks
- Small blocks of timber usually of hardwood which are designed to be laid in set
patterns
- Lengths range from 150 – 300mm with width up to 89mm and thickness ranges from
20 – 30mm
- Blocks are joined along their edges with a tongued and grooved joint and have a
rebate or chamfer along the bottom longitudinal edges
- Blocks should be laid from the centre of the floor towards the perimeter
- To allow for moisture movement a cork expansion strip should be placed around the
entire edge of the block floor
 4. Parquet
- Superior form of wood block flooring made from specially selected hardwood chosen
mainly for their decorative appearance
- Are generally smaller and thinner than hardwood blocks and are usually fixed to a
timber sub-floor which is level and smooth
- Fixing can be by adhesives or secret nailed
- Can be supplied as a patterned panel fixed to a suitable backing sheet in panel sizes
from 300 – 600mm square
5. Floor tiles
- Thin flexible materials and should be laid on a sub-floor with smooth finish
- 1 : 3 mix c/s bed or screed with a steel float finish is laid to the concrete sub-floor
- A mature concrete subfloor must be clean, free from dust and dampened with water to
reduce the suction before applying the bonding agent to receive the screed
- Screed are laid in bays less than 15m² to reduce shrinkage cracks
a) Flexible PVC tiles and sheet
- Hardwearing floor finish produced by a mixture of polyvinyl chloride resin pigments
and mineral fillers
- Produced as 300 x 300mm square tiles or in sheet up to 2400mm wide with a
thickness of 1.5 – 3mm
- Fixed with manufacturer recommended adhesive
- Laid from centre of the area towards edge so that if the area is not an exact tile
module an even border cut tiles is obtained
b) Thermoplastic tiles
- Also called asphalt tiles and produced from coumarone indene resins, fillers and
pigments
- Are hardwearing, moisture resistant and suitable for most situation
- Size 225mm² 3 – 4.5mm thick
- To make them pliable they are usually heated before being fixed with a bituminous
adhesive
c) Rubber tiles
- Produced from natural or synthetic rubber compound with fillers to give colour andtexture
- It’s hardwearing, quiet and water resistant. Suitable for bathrooms and washrooms
- Size 150 – 1200mm² and 3 – 6.5mm thick. Sheet size 900 – 1800mm width
- Fixed by rubber based recommended adhesive
d) Linoleum
- Produced in sheet or tile form from a mixture of drying oils, resins, fillers and pigments
which is pressed on to a hessian or bitumen saturated felt paper backing
- Gives a quiet, resilient and hardwearing surface suitable for most domestic floors
- Size 1800mm. width 2 – 6.5mm thick sheet tiles 300mm²
- Fixed by adhesive to any dry smooth surface
e) Carpet
- Produced from nylon, acrylics and wool or mixtures of these
- There is vast range of styles, types, patterns, colour, qualities and sizes available
- Laid over an underlay of felt or latex and secured by adhesives, nailing around the
perimeter
- Supplied in narrow or wide rolls
f) Cork tiles and carpet
- Cut from baked blocks. 300mm² and 5mm thick
- Are hardwearing, quiet and resilient fixed with recommended adhesive
- Treated with surface sealant to resist dirt and grit penetration
g) Quarry tiles
- Made from ordinary clays worked in a plastic from, pressed into shape and hard burnt
- Are hardwearing, good resistance to water and suitable for kitchens and entrance halls
- They tend to be noisy and cold.
- Produce in square size 100 x 100 x 20mm to 225 x 225 x 32mm thick
- Joint between tiles are grouted with 1: 1 c/s grout.
h) Plain clay tiles
- Produced from refined natural clays
- Denser than quarry - ranges from 75 x 75mm to 150 x 150mm