Here’s one thing that not everyone might think about when it comes to converting their loft – insulating it. Most people would be focused on building the staircase or designing the loft. Insulation would be the last thing they think of. And some might even wonder, why do I have to insulate my loft? Well, the reasons are pretty simple and logical. For one, you’d want your home insulated so that it would still be able to keep you warm. And two? There are building regulations that govern insulation within houses. 

So, how do you do it? Well, we’ve come up with this easy guide to provide you with information on how and what you would need to insulate your own loft. 

To begin with, loft insulation varies according to what your loft is going to be used for. If your loft is only going to be used for storage, then a cold roof option can be used. This means that the roof and loft aren’t really insulated. Instead, the insulation is placed in between the ceiling joists on top of your top floor. The insulation is meant to keep your house warm. However, if your loft is to be converted to a living area, then you’d have to create a warm roof. This means that the insulation will have to be inserted at the rafter level to ensure that the loft will remain warm as well. 

So, Where Exactly Do I Fit My Insulation? 

There are three main options – above, in between or below the rafters. The permitted type of insulation will usually be dictated by building regulations and local planning laws. Therefore, it is important to check in with the local building and planning authority to know how best you should insulate your loft. 

Between The Rafters 

If you are only installing insulation between your rafters, your insulation will have to be installed deeply as the minimum required insulation depth is 125 mm. And, that’s for the best phenolic foam insulation available. Other insulation materials may require more depth. This might be a problem for you if there isn’t enough space between your rafters. If so, you might have to try the other methods or do a combination of methods. 

However, there is also another problem with this installation method – minor condensation may occur due to the cold bridges. This condensation then would consequently cause the internal decoration to end up discoloured. 

Over The Rafters 

A continuous layer of insulation for this method solves the condensation problem of the previous method. However, this option is only possible for houses that are newly built or have been recently renovated with their roof tiles being removed and relaid. If your house is neither of these, this method will not work for you. Furthermore, despite it not having the condensation problem, this method still requires deep insulation. Humongous fascia boards and broad soffits will be required for this insulation method to be properly installed. 

Beneath The Rafters 

This method also solves the problem of cold bridging and is easier than the “Over The Rafters” method. However, this method requires a tradeoff as it can restrict the headroom available. In new builds, this headroom problem can be solved. However, in a renovation situation where the roof is going to be converted, it continues to pose a problem. This is thus unsuitable for lofts that already have low ceilings. 

So, What’s The Best Solution? 

Well, the most practical one would be a combination of between and underside methods. You would first place most of the insulation between the rafters and then have a smaller, additional amount of insulation installed on the underside of the rafters. For this method, insulated plasterboard would be a great choice of material. Plasterboard is also easily available and there are a plethora of stiff insulation products that are bonded to such boards. 

If your roof is not being stripped however, then you might want to consider a combination where you use between and under-rafter insulation. A ventilated airspace of five centimetres should also be situated between the upper-surface and between-rafter insulation. For this method, conventional sarking felt could be used and it will provide the best insulation for the cost. 

What Materials Are There? 

There are a great many options for insulation and your choice would mostly depend on your preference and financial ability. 


These are more expensive than other insulants as they are made of gas. However, they are great for use if you have limited space. 

Extruded Polystyrene 

This is a denser version and it is largely used beneath flooring, especially if it comes into contact with the ground. This would thus, not be the best option for insulating your loft. 

Multi Foils 

These are basically slim rolls of aluminium foil that are packed with layers of foam padding in between them. They are only 25 mm thick however, they provide a great amount of insulation. With their thinness, layers of them could be packed on as well. These foils are a great way to insulate a sloping roof. 

Natural Materials 

As the name suggests, natural insulation materials are used here. This is a method that is gradually becoming more popular as they are easy to work with and provide good insulation. They are more expensive than synthetic wools, however. Synthetic wools are often difficult to work with as they are made with harsh material such as glass fibres and minerals. Apart from that, wood fibres and hemp can also be used and they are available in either roll or slab format. This makes them perfect for insulating timber walls or roof spaces. 


Insulation doesn’t have to be a dry fixed material, like in slabs, rolls or boards. Instead, it can be blown into position by a nozzle. This is true for insulation that is made out of wool, fibres and plastics. It is also a great way to place insulation onto roofs as it is more convenient and efficient.

Insulation may not be the first thing you plan for when you decide to do a loft conversion. But if you’re going to be using the loft for something other than storage space, then it should be something to consider. After all, you don’t want to have everything else fitted in place and then realize that your loft is freezing cold!