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Everything you need to know about wall insulation

Everything you need to know about wall insulation

With the outside temperature having taken a bit of a dive over the course of the last few weeks, and with November getting ever closer, now is the time when we all start to to think about ways we can make our homes warmer, and ideally for less. 

Boosting you’re home’s energy efficiency if of course the key to lowering the cost of our heating bills and there are tonnes of ways of doing it, from insulating foam in the ceiling to those funny little draught excluding snakes designed to fit in front of rickety old door. For those who want to make a big difference to their home’s efficiency however insulating the walls will make a massive difference, with estimates from the Energy Saving Trust suggesting that the owner of a detached house could save as much as £455 a year on their energy bill by carrying out solid wall insulation. 

What many don't realise however is that the specific type of walls a home has will dictate exactly what kind of insulation can be installed.  


external view of a home extension

Cavity wall insulation 

Cavity walls are commonly found on properties that were constructed from the 1930s onwards and are intended to reduce the amount of damp found in homes. As the name suggests these types of walls contain a cavity between two layers of brick, this cavity makes fitting insulation into these properties quick and easy, so much so in fact that most properties in the UK now already have had this type of insulation fitted. 

Recently built properties of will already have this kind of insulation. However, if your home is over 10 years old then it is worth checking if it has been installed or not. 

The actual process of installing cavity wall insulation can be completed in some cases in just a few hours. Once the installer has inspected all of the walls of your home, they will drill several small wholes into the brickwork and then use a special machine to blow either fibreglass or polystyrene bead insulation into the crevice. Once they have completed the filling in the wall, they will cover back up the access holes, leaving them barely noticeable. 


rendered exterior of a house

Solid wall insulation

Solid walls are commonly found on older properties, and it’s very likely if your home was built before the 1920s that it is of solid wall construction, but there are two easy ways to find out what sort of walls your home has, if you are unsure — Firstly, if your home has an exposed brick facade you can find out by inspecting the brickwork, typically in solid wall properties you will find a pattern in the brickwork that alternates between them being length and width ways. If your property has been externally rendered then you can identify the wall type by measuring it’s thickness, Solid walls are typically less than 260mm thick (unless they are made from stone, in which case it is most likely to be a solid wall anyway). 

Unfortunately, the lack of a cavity can make solid wall insulation trickier, leaving essentially two options — external wall insulation or internal wall insulation. 

Internal wall insulation is the most popular option, as it is considerably cheaper than external insulation and will not alter the exterior appearance of a property, making it preferably for period of character buildings. It’s also a faster installation process and doesn’t require any scaffolding to be erected. 

Internal insulation works by installing either stuff walls or rigid insulation boards to the bare internal wall. The downside of internal insulation is that the process can be rather disruptive, with all of the fixtures and fittings of the wall such as power sockets, radiators and cabinets needing to be removed before work can begin on installing the new insulation. As the walls are physically thickened it will also make the room smaller by as much as 4 inches per wall. 

External wall insulation involves the installer fixing an insulating layer over the outside wall using a combination of adhesives and physical fixings, after which it is covered with a either cladding or render to protect the insulation, in many cases cladding or rendering the outside of a property can improve it’s appearance — but this leaves external insulation unsuitable for those who want to preserve the original features of their home, getting planning permission to do this could also be problematic if you live in a listed property or it is within an Conservation Area. While external insulation is as effective (if not more) than internal insulation, and it won’t reduce the size of your rooms. It is the most expensive form of insulation and takes the longest amount of time to install, often requiring scaffolding to be erected around the property, this means it may be best installed while other home improvements are being made such as to the foundations or roof of the property. 

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