Adhesives and Sealants
As Builders we need to know or be
able to locate technical information
about these products.
Adhesives
The best place to find information about these products is a manufacturers website.
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Adhesives work by linking to
materials and then solidifying
Due toSolvent loss (including water)
Chemical reaction.
Cooling of a pre-heated
adhesive.
Other names for adhesives
Glue
Cement
Solvent / cement: (used to
weld plastics rather than glue)
BRANZ bulletin 356 suggests:“The commonest cause of
bond failure is failure to follow
adhesive manufacturers
instructions.”
Storage or shelf life, length of time an adhesive can
be stored.
Pot life, after mixing time adhesives remain suitable
for use.
Mixing time, adhesives (like casein or aerolite)
require reaction time after mixing
before it can used.
Assembly time, time between adhesive application
and the application of pressure.
Curing time, time taken to attain sufficient strength.
Catalyst/hardener, a substance which initiates
adhesive to set.
Gap-filling, usually in the form of
a powdered extender which is
added to liquid adhesive.
Allows adhesive to bridge wider
glue line gaps (up to 1.3 mm)
without
affecting the strength.
Thermoplastic, adhesive
softens with heat.
Thermosetting, adhesive
hardens with heat.
Elastomer, adhesive with
elastic or rubber-like
properties. Often
marketed as adhesive /
sealant.
Adhesives are often
grouped into three types
Structural adhesives
Construction adhesives
Woodworking adhesives
STRUCTURAL ADHESIVES
Are high strength
adhesives used in
laminated beams,
structural plywood or boat
building.
CONSTRUCTION ADHESIVES
Are cartridge grade adhesives that are
normally used in conjunction with
fasteners for low stress applications i.e.
panel bonding.
The adhesive is cured by the
evaporation of either water or solvent.
WOODWORKING ADHESIVES
Different types of Poly Vinyl
Acetates (PVA) and aliphatic resin
adhesives dominate
the building-site woodwork glues.
 PVA is a white coloured, and
aliphatic, a cream coloured liquid.

.
Contact Adhesives
Two types of contact adhesive are
available Adoa F2 and Thixotropic Ados
F2
These glues are strong smelling and are
used to bond ,rubber, plastics,
timber,laminates,plastic,cork and
weatherseals
.
Sealants
Sealants are a non-rigid
(elastomeric) type material,
used to waterproof joints or
seal joints to prevent air
movement between various
building components
Sealants elastomeric
nature, allows the
sealant to expand or
contract within the
joints.
Sealants are generally
marketed as
“gunable” thick
pastes and packaged
in
cartridges or socks.
Compatibility of
sealant with substrate
is important (e.g.
sealants with an
acidic cure may not
be used to seal joints
in concrete products)
Bathroom and wet
area sealants often
contain anti-mould
inhibitors.
Common applications
Seals between pre-cast concrete units ( to
weatherproof or stop air movement)

Peripheral seals to weatherproof around
aluminium joinery.

Joints to external cladding and sheathing.

Expansion and contraction joints (high
differentials of thermal expansion)

Waterproofing and sealing in wet areas
(bathrooms and showers etc.)

Glazing

Sealing around pipes (through timber framing,
concrete construction)

Sealing joints in air conditioning ductwork.

Flexible joints (between concrete floors and
machinery)

As a flexible and waterproof pointing between
ceramic, earthenware tiles and stone work (often granite
or marble panels)
The selection of a sealant depends on:

Compatibility of sealant with the
substrate (will substrate need priming)

Width of joint.

Movement capability of the sealant
(expressed as percentage movement of joint
width)

Interior or exterior application,
amount of movement, heat, and chemicals.

Ease of installation, tooling off and
cleanup (two and three pot sealants are
messy and have limited pot life)

Toxic risks  Cost
TYPES OF SEALANTS
Oleoresinous sealant
Butyl rubber sealant
Acrylic sealant
Polyurethane sealant
TYPES OF SEALANTS
Oleoresinous sealant (Secomastic)
Called mastic.
Seals by remaining putty like (basically linseed
oil and whiting with different
oils and fillers to maximise retention of
fluids).
Accommodate about 5% joint movement.
Maximum 5 year life
.
Butyl rubber sealant (Stormseal, Seelastrip)
( turns into a rubber-like compound)
Performance is superior to mastic.
Uses are limited to bedding in applications and
pointing of glazing.
Accommodate limited movement
Maximum10 year life.
Acrylic sealant (No More Gaps, Gaps ‘n’ Cracks)
Fill gaps prior to painting with non-enamel
paints
Seals joints in acoustically designed areas.
Accommodate +/- 5% joint movement
Designed for interior use.
Polyurethane sealant (Uraflex)
May be formulated as one or two part sealant.
Good flexibility - 25% joint movement.
Durability of up to 15 years.
Used as a joint sealer (depending on the type
selected)
Polysulphide sealant (Thioflex 600)
Manufactured as one, two or three pot (different
formulations to address sag
resistance, width of joint, on-site conditions etc.)
A tough, rubber like sealer with excellent adhesion
and 25% joint movement.
Used extensively in the construction industry for
sealing horizontal and vertical
joints (5 to 50mm wide) between pre-cast and tilt-slab
components, and fibre
cement sheets.
Joint surfaces require priming.
Durability in excess of 20 years.
Silicone sealants
Acetic acid cure sealant. (Silaflex RTV)
 Used extensively for glazing applications,
expansion and waterproof joints in
ceramic tiling and stainless steel joints.
 Used in bathroom and kitchen areas (mould
inhibitor required)
 Withstand long term immersion in water (but
not permanent)
Not suitable for concrete, fibre cement sheets,
galvanised steel or
specified plastic or acrylics.
 Joint movement 10%
 Maximum 25 year life.
Neutral Cure (Silaflex B, Silaflex N, Silaflex
NG)
 Very good adhesion only if used with the right
substrate
 Use Silaflex B for timber, concrete brick and
fibre cement sheeting
 Use Silaflex N for coated and uncoated metals
(plumbing & roofing)
 Use Silaflex NG for glass, ceramic and plastics
Movements up to +/- 10%
Maximum 25 year life
Modified Silicones (also neutral cure) (Silaflex MS)
 Excellent primerless adhesion to all the
substrates mentioned above and
particularly powder coated aluminium.
 Paintable and won’t stain natural stone.
 High movement accommodation up to +/- 25%
 Maximum 25 year life -.
Note: Best option for a multi-purpose
sealant
Epoxy urethane (Nitoseal 280)

A three part, heavy duty sealant used for
sealing internal factory floor joints.

Movement capability of up to 10%.
Epoxy (Nitoseal 281)

A joint sealing compound for low
movement and hard wearing floor joints.
Bitumen synthetic rubber (Plastiseal)

A flexible gun applied sealant suitable for
sealing limited movement joints in
retaining walls, basements and the like. Bitumen
based is not compatible with
other sealants, however it may be used with
bituminous tanking i.e. Mulseal.
JOINT DESIGN
Joint Design should aim to:
Reduce the exposure of the sealant to the weather
Minimise the damage to the building should the
joint fail
Provide good access for joint repair or maintenance
Get a width to depth ratio of 2:1 with a minimum
depth of 6mm. Some joints may
require a 1:1 ratio.
Provide a bond breaker at the back of the joint so
the sealant adheres to the sides. If the joint fails the
bond breaker will be a backup seal.
Have clean straight edges at the joints.
Bitumen synthetic rubber (Plastiseal)

A flexible gun applied sealant suitable for
sealing limited movement joints in
retaining walls, basements and the like. Bitumen
based is not compatible with
other sealants, however it may be used with
bituminous tanking i.e. Mulseal.
E
HEALTH PRECAUTIONS
Adhesives and sealants contain hazardous chemicals
i.e. formaldehyde and
methyl-butyl ketone.
Health risks are caused by:
inhalation of the fumes
contact with the skin
swallowing
To avoid health risks:
Read manufactures hazard warnings
Use gloves. (Disposable gloves are cheap and easy to
use)
Wear eye protection if necessary.
Working area is well ventilated.
Wear a suitable mask if the fumes are likely to be a
hazard.