Posted by: |  Posted on:  |  No Comments »  |  Add comments  | 
Category: Insulation

Saving money by insulating your walls is nothing new, but if you haven’t done it yet it is probably because you don’t know where to start. This is our guide to putting that right!

We will link to the projects to show you how to insulate your walls, or get someone else in to help you if you prefer. The idea is that we will show you what needs to be done and why. Critically, if you understand why, then you are likely to make the right decision.

Why Insulate Walls?

Hot air rises, and most of the heat is lost through the roof. A big push on getting most insulation into people’s lofts has, on the most part, been successful. This is where you should start.

Assuming that the loft has been insulated and you have conducted basic draught proofing to stop warm air leaking out of your home, the next thing that you should consider is insulating the walls. The walls often have one of the largest external surface areas for heat to escape through and hence why they can account for so much heat loss.

Heat loss from a property

Potential for heat loss in your property

Therefore insulating them can help to prevent some of this heat loss; heat that you have paid for!

The Options to Insulate Walls?

If you have cavity wall, then it is much easier, cheaper and less disruptive to have the cavity filled with insulation. There are some circumstances where this is not possible, even if you have a cavity. For example, if there is a lot of driven rain, such as on the west coast, this can penetrate into the cavity and adding insulation here can cause issues.

Cavity fill insulation

Cavity fill insulation bening pumped in to cavity

Filling cavity walls with insulation is not a DIY job. It is injected in to holes that are drilled between the brick or masonry. While this not beyond the ability of some DIY enthusiasts, we don’t recommend doing it. Using a properly certified and professional firm will mean that the wall will be surveyed before hand, and should not be filled if it is not appropriate. You should also insist on getting the appropriate protections in the form of (insurance backed) warranties and guaranties.

Home’s that have been built before the 1920’s will not have cavities, so another solution needs to be found.

Here you have two options:

  1. External Wall Insulation – applied to the external walls of the house
  2. Internal Wall Insulation – applied to the internal side of the outside walls of the house

These are typically referred to as solid wall insulation, as they are generally applied to walls that are solid and don’t have cavities, but the same principle and techniques can be used on cavity walls if filling the cavity is not appropriate.

Solid Wall Insulation

Of the two options, external solid wall insulation is the more challenging and expensive, but it is going to be least disruptive particularly if you are going to live in the house while the work is going on. It will also change the character of the house, as you are adding a layer of insulation to the outside.

In simple terms, you add the insulation, secured as described by the manufacturer’s guidelines, and then you apply the external render finish over this. While this will be relatively simple, assuming you have all the right access equipment such as scaffolds, the extra thickness may result in having to get the eves and over-hangs extended to reach over the added wall thickness. This is where you are definitely moving away from a DIY job and will need to look for a professional.

Internal Wall Insulation is a project that is possible for a serious DIY enthusiast. There are a number of ways to tackle this kind of job, and the choice will depend on the space you have (you’ll be losing internal space to make room for the insulation) and the approach you want to take or perhaps your budget.

Insulation papering is the easiest and most space saving but least effective. This involves adding insulated paper to the walls to stop the heat (and noise) getting through. Thicknesses vary but they are typically around 10mm thick.

At the other end of the spectrum is the method where you build a new stud wall inside your outside walls, ideally leaving a 50mm air gap. Typically the stud wall will need to be 100mm, so you can see that this will take up a significant amount of space, but should be very effective, particularly if the wall is prone to damp.

In between these two options are a range of solutions which involve applying a reasonable thickness of rigid insulation to the wall and then coving with plaster boards. This is the most common approach, and we cover all the options, such as whether to use battens or not, where to put them and how to fix the insulation, including hanging insulating paper in our DIY insulating walls project.

Internal wall insulation is the most appropriate DIY task, and is a good project to tackle, although should be attempted by the more confident DIY-er as it can be quite a large project when fixtures and light fittings need to be moved.

Remember, if you want to go ahead but don’t want you do it yourself, you can find a tradesman local to you here.


Signup for the DIY Doctor Newsletter

See our Other Great Content