Cavity Wall Insulation

Cavity walls consist of two 'skins' separated by a hollow space (cavity). The skins are commonly masonry such as brick or concrete block. Masonry is an absorbent material, and therefore will slowly draw rainwater or even humidity into the wall.

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The cavity serves as a way to drain this water back out through weep holes at the base of the wall system or above windows. A cavity wall with masonry as both inner and outer skins is more commonly referred to as a double skin masonry wall.
Prior to any installation of our polyurethane products an intensive site survey is carried out to assess whether your property is suitable and will benefit from spray foam insulation. We will then confirm according to the requirements of the BBA if the property is suitable for installation.

The 3 basic steps for in wall insulation following our survey.
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Step 1 for cavity wall insulation

Drill access holes spaced at the correct hole pattern, this insures the cavity is fully filled, Over pressurisation does not occur and that the party wall is insulated off.

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Step 2 for cavity wall insulation
All chemicals are heated to the correct temperature then injected in to the cavity. We inspect this process with a camera to insure accurate equal filling is happening. We work our way up the wall until 100% of the cavity has been filled.
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Step 3 for cavity wall insulation
Following the cavity wall foam insulation we complete all final checks of vents, flue pipes etc and insure all appliances are fully operational. Your safety is paramount to us and we never leave a job until all post checks have been completed and the results successful.

We then make good all areas by patching with a mortar to suit the existing on the property the best we can.

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Technitherm video

"Why use polyurethane spray foam over conventional methods"

Cavity wall foam injection is the most cost effective way to insulate your cavity wall. Polyurethane cavity wall insulation bonds to virtually any material and expands to fill the whole cavity. As its injected as a liquid all gaps are filled during the expansion process and the inner and outer wall bonded together, this adds greater strength to the wall and stabilises the structure.

Injecting polyurethane foam-

Combats wall tie failure.
Eliminates air leakage.
Overcomes structural problems.
Makes the property 3 times stronger in the face of gale force winds.
154KNm-2 adhesion to Brick work
163 KNm-2 adhesion to Block work
Does not shrink or settle in the cavity wall.

Spray Foam Insulation, Cavity wall insulation, Stop Condensation

Wall stabilisation
Solving the problems of Wall-tie Failure and Poor Levels of Insulation using Structural Rigid Polyurethane cavity wall insulation.

Over the last 30 years polyurethane foam has been used to stabilise walls suffering from tie 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 properly spaced holes in the outer leaf. The foam expands in the cavity and sets to become a substantially closed-celled, cross-linked, rigid polyurethane foam which strongly adheres to the inner and outer leaves, so that they become bonded together.

Injection foam insulation has superior bond strength. The system has been widely used for the restoration of cavity walls in which the wall ties have become ineffective due to corrosion. The foam is a satisfactory replacement for normal metal wall ties.

Superior insulation
You can upgrade the thermal performance of a property to meet Building Regulations without the need for expensive, disruptive external cladding. This gives energy savings and reduced CO2 emissions. And because polyurethane expanding foams mould themselves into the fabric of a building, they seal out draughts and reduce air leakage.

Closed cell foams are resistant to driving rain so the foam stays dry with no loss of thermal properties.

Additional stabilisation
Polyurethane stabilises a wall by adhering to the surfaces of the cavity and providing a continuous structural connection between the two leaves. It has the ability to form a good bond with surfaces that are unprepared and in a raw state. The adhesive bond strength is better than 60KN/m2 which is generally in excess of the wind suction likely to occur on the wall.

Remedial mechanical fixing systems using steel bolts or pins rely heavily on a secure fix to the inner leaf. This is often inadequate and sometimes impossible with hollow blocks. It also introduces many more thermal bridges into the structure.

The permanent bond to masonry prevents shrinkage or settlement, which leads to 'cold spots'.

Stabilisation and thermal insulation of cavity walls is covered by a British Standard Code of Practice, BS7456.


Thermal conductivity <80mm thick
0.028 W / mK
Thermal conductivity, 80-120mm thick
0.026 W / mK
Thermal conductivity - 120mm thick
0.025 W / mK
Compressive strength -normal to major plane: ( 50mm cavity )
210 kPa
Shear strength - parallel to major plane: ( 50mm cavity )
241 kPa
Water Vapour Permeability parallel to foam thickness
5.9ng / ( max
Closed Cell Content
Burning Characteristics
Less than 40mm
Tensile Adhesion to Masonry:

Aerated Concrete
51 kPa
155 kPa
Breeze Block
166 kPa
Uniform, fine cell structure
42 Kg / m3

UK Coverage including Wales - Abergavenny, Ammanford, Haverfordwest, Carmarthen, Swansea, Port Talbot, Bridgend, Merthyr Tydfil, Caerphilly, Cardiff, Newport, Llanelli, Llandeilo, Pembroke, Glamorgan, Pontypool, Pontypridd, Milford Haven, Maesteg, Neath, Ebbw Vale, Aberdare, Cwmbran, Llantrisant, Barry, Hereford, Brecon
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