Types and Applications :: Polyurethane insulation
Kershaw sprayed and injected polyurethane foam systems provide an ideal way of achieving extremely high insulation standards whilst providing effective controls against unwanted air leakage and preventing condensation. The insulation value of polyurethane is amongst the best available as the foam seals all gaps and moulds itself to all contours. Polyurethane has the ability to provide significant structural strength and it creates its own vapour control layer – which is essential in today’s highly insulated buildings.
Applications
New Build
Spray applied polyurethane foams are used in:
- Timber framed walls,
- Pitched and flat timber roof constructions
- Timber and concrete ground-floor constructions
Stabilisation and Insulation of Existing Buildings
Spray-applied foam is applied to the underside of a roof and bonds
slates and tiles to each other. It is also applied to structural
or supporting timbers to replace the anchorage of fixing nails. It
is a much less costly alternative to re-roofing and can be applied
to various roof coverings.
Application permanently cures the problems of nail fatigue and makes
the roof much more resistant to storms or other direct impact damage.
Polyurethane is liquid when it is applied, thus it seeks and seals any unwanted air leakage, preventing the ingress of wind-driven rain, snow and dust. At the same time there is a dramatic reduction of heat loss.
Installation
at rafter level keeps the loft space warmer and prevents condensation
build-up which can potentially occur when increasing insulation at ceiling
level.
The warmer, drier, cleaner roof space eliminates the risk of pipes and
tanks freezing. The spray applied foam used in lofts meets Class 1 Surface
Spread of Flame when tested to BS 476 Part 7: 1997.
Polyurethane foam also slows the deterioration of tile/slates by frost.
Slates and tiles will be less prone to damage by impact as the foam distributes
the forces. Where slates and tiles are damaged after installation, they
may be replaced by cutting away the foam from the underside, replacing
the slate or tile and re-treating the affected area. Test data confirm
that although the spray applied foam adds only 2kg/m² total weight
to the roof, treated roofs have sufficient cohesive and compressive strength
to transfer the loads imposed by the roof covering should the battens
be deficient.
Spray applied foam contains no nutritional benefit and is not attractive
to vermin or pests and closes off common access routes.
Tiles and slates adhered in place prevent theft. It has been found to be particularly suitable for historic and listed buildings where it is important to maintain the original character of the roof.
Cavity Wall Stabilisation and Insulation
Structural rigid polyurethane foam can solve the problems of wall tie
and mortar joint failure and poor insulation levels.
Over the last 30 years polyurethane foam has been used to stabilise
walls suffering from tie and mortar joint failure. Studies made over
the last decade, in conjunction with the Building
Research Establishment, have highlighted the problem and have confirmed
there are millions of dwellings at risk. A suitable polyurethane foam
system may be injected into a masonry cavity wall by injecting liquid
polyurethane through holes in the outer or inner leaves. The foam expands
in the cavity and sets becoming a closed-celled, cross-linked, rigid
polyurethane foam which strongly adheres to the inner and outer leaves,
so the leaves become bonded together.
Polyurethane has a superior bond strength, which makes it ideal for the restoration of the structural integrity of cavity walls within which the wall ties have become ineffective due to corrosion. The foam is a satisfactory replacement for normal metal wall ties.
Insulation Properties
Cavity reinforcement polyurethane foams have excellent insulation properties
and are resistant to flooding. The thermal performance of a property
is improved to meet current Building Regulations within the space of
the existing cavity. This gives energy savings and reduced CO2 emissions.
Polyurethane expanding foams mould to the fabric of a building, sealing
out draughts and reducing air leakage. Closed cell foams are resistant
to driving rain thus the foam stays dry without losing its thermal properties.
(They are approved under BBA Certification for installations up to 12m
in height in all exposure zones).
Stabilisation and thermal insulation of cavity walls is covered by a British Standard Code of Practice, BS7456.
Agriculture
The agricultural sector is dependent upon good insulation particularly
within root crop stores and livestock buildings. Polyurethane offers
a high level of insulation thus a thinner layer can be installed.
A further advantage to the system is its ability to completely seal buildings,
which
The system is significant in reducing gassing and fogging.
Industrial/Commercial
Spray applied foam provides the ideal solution for insulation and condensation
control in industrial and commercial buildings. It can be applied to
almost all surfaces to improve the working environment and cut fuel
costs.
Polyurethane is an ideal solution for asbestos encapsulation.
Applications include factories, offices, exhibition halls warehouses
and football stadiums. In new and existing structures polyurethane foams
are economically applied to the underside of steel, asbestos and aluminium
roofs and walls.
A typical U value of 0.023 W/m²K gives excellent insulation benefits
reducing 'U' values from 5.0 W/m²K to 0.25 W/m²K with as little
as 85mm of foam. The finished surface is non-toxic and odourless, has
low water absorption and high resistance to chemical attack. The resilient
surface can be high-pressure jet washed.
Class 'O' fire resistant foam systems are available which are coated with a single component, water-borne intumescent paint.
