Solid Wall Insulation FAQs

Tŷ-Mawr ‌‌ posted this on 9 Aug 2016

Traditional Solid Walled Building - 'breathing'How do solid walls work?

Solid walls are designed to enable moisture to be readily exchanged with the indoor and outdoor environments. Therefore when insulating materials are introduced, great care needs to be taken to evaluate the 'breathing qualities' of the chosen material and hence the impact on the building.

Solid-walled buildings are also able to absorb heat over time and then slowly release it (decrement). This ability is referred to as the thermal mass; it has a significant effect on the internal environment. It is, therefore, necessary to consider the impact on this quality as well.

Traditional solid walled construction buildings can be prone to damp (moisture in liquid form) and salts. It is therefore important to seek the advice from someone experienced with solid walled construction buildings when considering insulating. It is especially important if the building has been empty or has had a roof missing or is/has been excessively wet for a long period.

Before you even consider insulation, make sure your walls are functioning correctly and are dry.


How do I know if I have solid walls?

The majority of solid walled buildings in this country are built of brick or stone and tend to pre-date the 1930s. For brick built buildings, if the wall is more than 25.4cm thick, then it probably has a cavity; solid brick walls are usually around 22cm thick; stone walls vary considerably from 10cm to 100cm!

Your house may have extensions from different periods and may, therefore, be constructed with different methods. This will need to be understood prior to making a choice about how to upgrade the insulation value of your home/building.


Why bother to insulate solid walls?

  1. To save energy and improve the internal comfort - heat will always flow from a warm area to a cold one. Therefore the colder it is outside the faster heat from your home will escape. Solid wall insulation will slow down the rate at which heat escapes, keeping your home warmer for longer. Adding insulation, either internally or externally, reduces what is known as the U-value - the more slowly that heat is lost which will ultimately reduce your energy consumption.
  2. To prevent cold bridging which occurs when a material that is a good conductor of heat makes a 'bridge' between the warm interior and the cold exterior.


How do I insulate solid walls?

In this website we have presented some of the options we have been developing over the years to help insulate buildings whilst allowing them to maintain breathability, as requested by building regs English Part L 3.8 & 3.12, Welsh Part LB Section 12.

There are essentially two methods of insulating solid walls:

  1. Externally
  2. Internally


Types of solid wall insulation Savings per year CO2 saved per year
Internal Around £380 2 tonnes
External Around £400 2.1 tonnes

*Estimated figures based on insulating a gas-heated semi-detached 3 bedroomed home.

Source: The Energy Saving Trust




Categories: FAQs