Solid Wall Insulation

What is solid wall insulation?

If your house was built prior to the 1930s the chances are that it will have solid walls (unless it is very old) – which is simply a solid layer of masonry bricks. Insulating your wall regardless of whether it is cavity or solid (or even timber framed), is a great method of making your home more energy efficient. The insulation will minimise heat loss in the winter, saving you money on your heating bills and preventing your home getting too warm in the summer, helping to keep your home at a more comfortable temperature.

According to research twice as much heat could be lost through an un-insulated solid wall as through an un-insulated cavity wall. However the great news is that solid walls can be insulated, both internally and externally and perhaps more importantly, the cost of the work is covered by both ECO and the Green Deal making it a very economical proposition.

The science behind insulation

If hot air and cold air are partitioned by a wall, heat will transfer through the wall eventually cooling the room until an equilibrium is reached (where the outside temperature is equal to the inside temperature). In reality this very rarely happens, because rooms tend to be heated; so as heat escapes through the wall, more hot air is supplied by your heating system, keeping it at a comfortable ambient temperature. If the thermal gradient is larger, for example on a cold and wintry day, the movement of the thermal energy across the wall will be accelerated.

Insulating a solid masonry wall helps to provide a thermal barrier, which helps to slow the movement of heat escaping out into the external environment.  Less heating is therefore needed to keep the house at the required temperature.

R-value and U-value Solid Wall Insulation

The R-value is the measure of thermal resistance used in the building and construction industry today. The higher the R-value, the better the insulating properties of a material – so you should be looking to insulate your house with materials displaying a high R-Value. Confusingly, you may hear the word U-value also banded round, this is exactly the opposite, which describes the ability of a material to conduct heat, so you want your insulating material to have a low U-value.

Types of Solid Wall Insulation For Your Home

Both internal and external insulation are great at keeping your home warmer, lowering your heating bills which in turn cuts carbon emissions. However, both solutions have a different impact on your home, which is explained in the following section.

Internal Solid Wall Insulation

There are a couple of methods to insulate a solid wall internally, which are to either use a rigid insulation board or build a stud wall. This will decrease the floorspace of a room (as per the thickness of the insulation board or stud wall you use). We recommend you get a professional in to complete this type of work, and you do not undertake it as DIY unless you are very experienced. Internal solid wall insulation can be as thick as 100mm, so your room will ’shrink’ wherever it has an external supporting wall. A fairly new solution to this ’shrinkage’ problem is using insulating wallpaper, which at only 10mm gives you the benefits of internal solid wall insulation, but has a smaller impact on the size of your room.

External Solid Wall Insulation

For external wall insulation you need to employ a professional and you also need to consider local building regulation. This is because this process involves covering the original brickwork and could significantly alter the current appearance of the property, out of step with the local area. Once any planning permission has been granted the home can be insulated using an adhesive type material which is fixed to the wall, then plastered over. The finish applied to the external wall can be any combination of texturing, painting, tiling, masonry work and /or cladding.

Advantages and disadvantages of internal solid wall insulation

Advantages of Solid Wall Insulation

    • Cheaper solution than external insulation
    • No aesthetic changes to the outdoor appearance of your home
    • Works well when the home its self is going through a process of internal renovation

Disadvantages of Solid Wall Insulation

    • It will reduce the room you have in the living areas by up to 10cm (Estimated the thickness of material can be up to 100mm)
    • Won’t necessarily get rid of any damp problems, which need to be tackled properly

Advantages and disadvantages of external solid wall insulation

Advantages of solid wall insulation

    • More expensive than internal insulation
    • Less disruption as the work is carried out outside
    • Renews the appearance of your home’s external appearance and increases the lifetime of the brickwork
    • Complements other refurbishment work
    • An opportunity to fill cracks and holes in the brickwork, which will help educe the draught problems (see Draught Proofing for more information)

Disadvantages of solid wall insulation

    • However planning permission may be required
    • Any work needs to comply with local building regulation
    • May not solve all damp issues
    • Work is not recommended if the building is not structurally sound

Costs of solid wall insulation

    • Around £100/m2.
    • Additional costs for downpipes, gas pipes, boiler flues and dishes
    • Subject to render strength – additional cost to remove old/weak render