Cavity Wall Insulation and Advantages

Cavity Wall Insulation and Advantages

Imagine a situation, wherein a sudden surge in the oil and gas prices affects the industrial countries; supplies of oil and gas are severely hit and worldwide price hike has started taking their toll. Doesn’t seem like a possibility, does it?? But this is what exactly happened in the 70s energy crisis. As years went by, increase in population, increase in the number of vehicles for various purposes, energy prices are still surging high, along with another severe crisis – Global Warming is looming upon us. The need for saving energy, reducing pollution, and above all, reducing global heat, has been the need of the hour for, for long. This is the reason that insulation has become a necessity for the entire world.

The government of the UK and the US are focusing upon the heat produced by homes, buildings, and other establishments. Insulating houses have been a long-proven suggestion that has been brought into action. A house can have loft insulation, cavity wall insulation, and external insulation. Structurally, houses and buildings were made with single-wall before the 1920s. Therefore, no scope of insulating the houses from within or outside was thought of.

What is a Cavity Wall?

A Cavity Wall is a space between two separate walls built next to each other with a thin space or cavity between them. One is the internal wall and the other is known as the external wall.

Present-day structures are different and most houses have this cavity between the two-layered walls.

The Necessity for Insulation

Insulation is necessary for buildings both internally and externally, to reduce heat loss. This helps in reducing carbon footprint and helps in reducing global warming.

What is Cavity Wall Insulation?

What is Cavity Wall Insulation

Insulation in the cavity walls is a method by which we reduce heat emission from the houses by filling in the wall cavities with thermal insulators. The thermal insulators balance the heat by trapping the heat in innumerable gas-filled pockets. Therefore, the heat passes through these pockets and the bricks, before being released into the atmosphere. By then, the heat of the air decreases, and much cooler air is released outside through the walls.

Similarly, during winters it keeps the house warmer and does not allow the cold air to seep in through the walls. When the heating system is turned on during winters, the warm air does not directly seep out through walls, and thereby, environmental heat is reduced.

Homes having single-walled structures too have spaces in-between the bricks wherein the insulation can be injected. These insulations are inexpensive, easy to install, and cannot be seen from outside. A balanced temperature is thus achieved and draughts are reduced.

Types of Cavity Wall Insulators

Insulation with Blown Mineral Wool

wall insulation with Blown Mineral Wool

Insulation in walls is always done by a mechanical injection through which the insulant is injected inside the cavity walls. This way, a complete fill for the cavity is ensured.

The mineral wool is a mechanically granulated crushed glass or rock wool, seasoned with a binder or water repellent during their manufacturing process. Passing through a strict quality control check, they are produced and certified along with the equipment used in the process. The certification is done through the British Board of Agrément. Once the installation is done, the mineral wool continues to make a lifelong impact as an insulant for the wall cavities.

Advantages of Mineral WoolInsulator

  • Good thermal conductor
  • Saves Energy
  • Soundproof insulation
  • Inexpensive
  • Inflammable
  • The insulating properties of the material never wear out
  • Mineral wool is not affected by molds as it is not capable of absorbing moisture
  • It is recyclable
  • Negligible carbon footprint

Insulation with E.P.S. Beads

wall Insulation with E.P.S. Beads

E.P.S is Expanded Polystyrene beads, produced from a solid plastic material – polystyrene. It is a rigid foam material bound with an adhesive or binding agent at the time of insulating a wall. The beads are produced in a specified size and thickness that doesn’t get changed when injected into the cavity of the wall.

After installation, the beads in the cavity remain in their perfect form as an insulator, lifelong and without any further maintenance. Once installed, the bead filling in the cavity will remain an effective insulant for the life of the building and will require no further maintenance.

Advantages of E.P.S Insulation

  • Light Weight
  • Saves Energy
  • Moisture Resistant
  • Durable
  • Thermal-efficient
  • Versatile
  • Easy to install on-site
  • Sustainable Longevity
  • Negligible environmental footprint

Insulation With Polyurethane Foam (PU foam)

A by-product of polymers or plastics, Polyurethane can be a solid, rigid product or can be flexible like foams.  Therefore, they are called Foams. Rigid foams are mainly used for the thermal insulation of buildings.PU foam can be injected into the cavities of the walls as insulation material, that binds the inner and outer leaves together, to strengthen your homes

Advantages of PU (Foam)

  • It acts as a barrier to air and moisture
  • Mold resistant
  • It has a high R-value, that prevents heat transfer
  • Saves Energy more
  • Rigid and more stable than the other two options
  • Easy to use

Installation Points to be Remembered

  • Suitability of any type of aforesaid installations should be done after a pre-installation survey is thoroughly done.
  • The ventilation of the house should be checked properly. Openings for combustion air, vapor, and fungal or bacterial must be addressed before the installation.
  • Underfloor ventilation should be assessed for sleeving or other cavity closers.
  • All holes for injecting the material in the cavities should be properly covered after installation.
  • All the air-releasing vents and chimneys in the house should be properly checked and made functional before installation so that problems do not arise later.
  • In case of old installations, or wrongly installed insulations, refurbishing should be done after a thorough assessment of pre-existing problems.

The inflation in fuel prices, mass-scale usage of energy globally, and the rising heat made the homeowners rush for various types of insulations between the 70s-90s. Unlimited retrofitted insulations by untrained workmen became a nightmarish installation for thousands of homes in the UK. Incorrectly installed insulations had a lot of problems to be faced then. Seepage, patches of damp walls, structural problems, fungal and mold problems were some of the issues faced by the earlier installations. Respiratory and other health problems started.

Presently such persisting problems have been dealt with in the latest processes of installations. More benefits have been added to the cart regarding cavity wall installations. 


1. No Disturbance because of the Installation work as mostly it is done outside.

2. With the latest technologies and development of various other types of equipment, it is much easier nowadays to install insulators with the help of adhesives that do not produce chemical fumes as in earlier times.

3. Installation process is so easy that regular heating lights and other electrical gadgets can immediately function.

4. Beads are so well-bonded with the adhesives these days that any other work post-installation can be done without the fear of leakage.

The Cost Incurred

The property type denotes the cost of the installation of the insulation done. The cost of the cavity wall insulation depends on the type of property you have. Mostly, a single-premise which is not attached to any adjoining home, the cost is estimated up to£725 for cavity wall insulation. A semi-detached home will cost around £475 for insulation in the cavity walls.

Child Benefit Claim TypeIncome
Single & 1 Child£18,500
Single & 2 Children£23,000
Single & 3 Children£27,500
Single & 4+ Children£32,000
Couple & 1 Child£25,500
Couple & 2 Children£30,000
Couple & 3 Children£34,500
Couple & 4+ Children£39,000

“If an applicant is using child benefit as the qualifying benefit for the insulation grant then their income from all sources (after-tax) must not exceed the limits shown below. The amount of income varies depending on whether the applicant is a single claimant or part of a couple and the number of children they are responsible for.”

Free Insulation Grant by the UK Government

Free Insulation Grant by the UK Government

The grants offered by the UK government fall under the Energy Company Obligation (ECO) scheme. This grant is a scheme to handle the problems faced by any energy crisis in the country. It is being funded by the largest utility companies in the UK.

This scheme has been introduced to help the low-income group of homes in England, Scotland, and Wales. The sole purpose of this scheme is to make their households more energy efficient and reduce their carbon footprint. Still, there are some criteria to be followed, and not every household can apply for these schemes. The eligible household can apply for this. Each eligible household is given a government-registered installer who will do the insulation installation. This grant is not to be paid back by the households to the government or the installer.

Cavity wall insulations are not quite expensive to install but it is very lucrative for the energy suppliers in the UK as their targets are quickly and easily met with. The house that has been built after the 1920s usually have a cavity wall in them.

Flat owners or tenants, need to take permission from the nearby properties or other flat owners if they happen to share the cavity walls. In most cases, timber-framed, metal clad and stone properties are not suitable for cavity wall insulation. In all cases, a survey is carried out before installation thus it allows the surveyor to bring up any cases where the installation may be a problem. 

ECO Scheme Offerings

“The ECO scheme offers grants available for different types of insulation. Homeowners can be eligible for more than one grant.

  • Loft
  • Internal wall cavity
  • External wall cavity
  • Room in roof

You may be offered enough to fund 100% of the cost of the installation but some homeowners will only obtain some of the money and will therefore need to contribute to the costs.”

Factors Relating to Grant Eligibility

  • This governmental scheme aims to achieve a higher energy efficiency level, by helping only low-income groups of households in the UK. Under this scheme, the heating bills are also reduced. This scheme legally initiates the cavity wall insulations along with the energy suppliers to install energy-efficient homes.
  • To be eligible for free insulation in this scheme, you should be an owner of the house or a rent has been privately given to you by the legal owners. It is also necessary that the property owner has been before the year 1983 as all those walls have a cavity in them.
  • As per the government eligibility norms –“Internal wall insulation and roof room are also free to people receiving income/disability benefits or tax credits as long as the property does not have mains gas. If the property is on the gas network a grant of up to 75% is available with a 25% contribution towards the cost of the insulation made by the homeowner.”
  • Before installation, a thorough survey is done for legalities. The property must be owner-held or on rent when the survey is conducted. If the household is occupied, there must be a valid gas bill under the gas network of the area that should be produced.

Eligibility Criteria Cavity Wall Insulation?

  • To be eligible for free cavity wall insulation, then you or someone in your home must be a recipient of one of the following benefits: 
  • Armed Forces Independence Payment
  • Attendance Allowance
  • Carer’s Allowance
  • Child Benefit
  • Child Tax Credit
  • Constant Attendance Allowance
  • Disability Living Allowance
  • Income-Based Jobseekers Allowance
  • Income-Related Employment Support Allowance
  • Income Support
  • Industrial Injuries Disablement Benefit
  • Pension Guarantee Credit
  • Personal Independence Payment (PIP)
  • Severe Disablement Allowance
  • Universal Credit
  • War Pensions Mobility Supplement
  • Working Tax Credit


So many benefits and advantages and reducing the carbon footprints, along with various government schemes and offers, one should positively go and get cavity wall insulations done. To be more environment-friendly, now we need to be more proactive.