Last edited 12 Sep 2019

Insulation Essentials Every Self-Builder Needs to Know

Self-building, whether a new home or an extension on your present one, is a great way of saving a lot of money. If you have the requisite skills, and the right tools, you may be thinking about such a project.

There’s one area that we want to talk about in this brief article: insulation. Insulation is an absolute essential of any building and needs to be implemented in many places to keep heat in, and to keep cold out!

The Government provide guidance relating to insulation within their Conservation of Fuel and Power Document which outlines standards for the energy performance of new and existing buildings in England.

Let’s have a look at some of the essentials you should know when you come to your self build and its necessary insulation.

Insulation Essentials Every Self-Builder Needs to Know (2).jpg


[edit] Insulating Your Roof

It is a fact that as much as a third of the heat loss in a home will likely be due to a poorly-insulated loft. Add that up over a year, and it’s a lot of money! Insulating the roof correctly is therefore of vital importance, and should be done carefully and using the right materials.

The general advice is to insulate the loft using 300mm of loft insulation material. This may require you to use three layers of 100mm material to ensure the loft has the right amount of protection.

It is also advisable to use taller joists than standard if you are going to put boards over the insulation. This is because the material does its job best when not compressed. Loft insulation really is among the most important areas of the home – after all, we all know that heat rises!

[edit] Insulating Your Walls

Insulating the walls can be done in a number of different ways, and the best depends upon the type of wall you are building. The most common type of wall for new-builds is that in which a cavity is present – and this cavity is the prime place for the principle insulation of the walls.

Materials for use inside the walls as insulation tends to be either mineral wool, polystyrene granules, or cellulose fibre. Even if you are doing the job as a self-build DIY project, you should have an expert assess the walls for cavity insulation, as poorly fitted insulation – or the wrong type for that wall – can lead to problems such as damp at a later date.

The assessor will also advise on the best way to tackle instances in which the cavity is not of uniform width, as this can also cause problems. Apart from the cavity, you might want to insulate the inner of the wall with thermal blocks or board, as this can lead to even more efficient insulation – once again, have an expert advise you on the right method.

Bear in mind that a poorly-insulated wall may account for as much as 50% heat loss from within the home, so you really do need to get it right.

[edit] Insulating Your Floors

Floor insulation can save you as much as 10% heat loss, the typical amount lost through lack of floor insulation in the ground floor of an average house. This is an important figure, and it is relatively easy to make sure your floor insulation is up to scratch.

To insulate floors you need to use rigid insulation board, and the best time to start putting things into place is when you are installing your slabs and pouring the foundation. This will enable the job to be done quickly, accurately and with the most efficient results.

Bear in mind the ground you are building on: houses that are built on dry soil are generally likely to lose less heat than those built on wet soil. Also, the type of building has an effect: a detached house will lose more than a terrace, for example, thanks to having more external walls.

If you are installing underfloor heating you will need to assess the situation and amend the thickness of your floor insulation accordingly, as it can make a big difference.

If in doubt, check with an expert about the right way to install your floor insulation, and the best materials to use, to ensure you get the best results from the job.

Insulation Essentials Every Self-Builder Needs to Know (5).jpg

[edit] Other Internal and External Insulation

There are many further insulation methods that can be put into place in order to ensure your house is as warm as it needs to be, and does not lose heat. We cannot stress how important it is to prevent heat loss. Heat loss – whether through the roof, walls, floor or by other means – is energy loss, and that means extra money for you.

Furthermore, a house that is not correctly insulated and is losing heat will force the heating system – and air conditioning should you have it – to work harder than it should. This can lead to overwork, breakdowns, and added expense.

The savings you will make by ensuring you have effective insulation can be quite amazing, so you need to make sure your self-build is insulated properly, and while you’re building it is the easiest and most sensible time to put insulation in place.

There are a few other factors to consider when it comes to insulation, one being additional internal insulation. Builders are frequently turning to installing a vapour barrier and insulated plasterboard or dry-lining to the inside of external walls. Although this is an effective method of adding insulation, it can also take away a small amount of space inside the room, which many people do not want to lose.

Another method of increasing insulation efficiency is to apply expanded polystyrene slabs – there are other materials, this being the most popular – to the outside of the walls, coupled with a steel mesh to enhance strength. Once rendered with insulating cement, the walls will keep heat in very effectively, although this is not a cheap process in any way.

Insulating your self-build should be part of the process, and you should plan it into the build itself. Do it right, and you overcome the need to retro-fit insulation in places that might be awkward to reach, and you have built yourself a ready-insulated home that will offer the highest levels of energy-efficiency.