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Cavity Wall Insulation

Cavity wall insulation is a common solution for thermal transmission in buildings throughout much of the world. 

Buildings constructed since the early-to-mid 20th century typically have an outer wall with a cavity. Originally designed to better prevent water from coming through, since the 1960s and 70s these have often been filled with insulation – primarily for thermal performance.

Cavity wall insulation can bring additional benefits by reducing carbon emissions – and improving health and indoor comfort1.

Without proper insulation, in hot climates, heat will easily come in, increasing the need for cooling. This will lead to higher energy bills.

Discover more about the benefits, products, and installation methods of ROCKWOOL cavity insulation today.

Why do we need cavity wall insulation?

Fitting insulation for cavity walls is among the quickest and most cost-effective ways to improve energy efficiency. Whether it's slabs for new builds and extensions.

Materials with strong thermal insulation properties are key to delivering effective external walls2An uninsulated cavity will cause a lot of heat gained during a hot period.  

Cavity wall insulation acts like a blanket that stops cool air from escaping. It retains the cool air and spreads it around the internal space. 

In hotter climate conditionsinsulation can help keep the home cool or reduce the need for air conditioningassuring the property maintains a pleasant temperature and doesn’t overheat. 

Key benefits include: 

  • Improved energy efficiency and warmer surface temperature on the inside of the outer wall 
  • Enhanced fire safety – especially around openings, preventing a fire from spreading through the cavity 
  • Reduced cooling costs 
  • Quick and easy installation 

Calculator and savings

The exact cost of installing cavity insulation and the energy savings it can bring will depend on property size and type – as well as local building practices and energy supply.

Stone wool insulation can be installed as partial or full fill, with the amount required determined by the number of walls and the type of material used.

Use our ROCKWOOL U-value calculator to determine the thermal performance of the building’s walls and possible cost savings. For more details on technical specifications, visit our ROCKSPEC Specification Toolkit.

Application, BIM, Wall
Using natural air to insulate, thermal performance does not deteriorate over time. Studies show a stable performance even after more than 55 years. The material will last the lifetime of a building.

Roger Peeters

ROCKWOOL Group Product Manager

Case Studies

The challenge

Silken Park in west Dublin, Ireland, was conceived as a new build housing development designed to offer cost-effective, low energy housing that would minimise environmental impact. The homes needed to be comfortable, while still delivering strong thermal performance.

The solution

To create a cost-effective building envelope, Silken Park saw a ‘fabric-first’ approach to construction. This aimed to ensure all buildings were airtight and well insulated, meeting the latest building regulations and Passive House standards. Several ROCKWOOL cavity insulation products were used.

The results

Our environmentally friendly and effective insulation ensured that the building fabric across all units in Silken Park saw significantly reduced heat loss.

Silken Park
By combining simple wall construction, good solid windows, air tightness, ventilation, and above all, high levels of insulation, we will have a very happy customer, with a healthy home and – most importantly – very low energy bills.

Barry Durkan

New Homes Director, Ecofix UK

Sustainability and energy efficiency

ROCKWOOL cavity wall insulation is focused on sustainability. Our key aim is to assist with the construction and development of energy-efficient buildings, using effective materials from a sustainable source.

Our products help property owners and industry professionals comply with market requirements - and go beyond them. We strive to work towards NZEB (nearly zero-energy buildings) through highly energy efficient designs that promote indoor comfort and quality.

product, wall, outer wall, wall insulation, cavity wall, insulation granulate, blown-in insulation, installer, fillrock kd, einblasdämmung, germany

FAQs

FAQs

Does cavity wall insulation keep a house cooler in summer?

Yes – it can help to prevent heat coming in during a warm period, as well as retaining heat when it’s cold outside. The need for cooling and air conditioning will be reduced significantly.

Does cavity wall insulation stop damp?

This depends on the materials used. Stone wool insulation is a breathable material that lets vapour damp pass through it easily, reducing the risk of condensation on the inside of the building.

How long does cavity wall insulation last?

It can last as long as the building itself. ROCKWOOL insulation has a proven lifetime of over 50 years, for example.