A closer look at thin internal wall insulation

A term many may have been hearing more recently, is Tiwi, referring to thin internal wall insulation. To meet low U value requirements, wall insulation materials like mineral wool, fibreglass or foam have typically increased wall thickness by 50-100mm, decreasing valuable floor space for residents. With 1.1 million people across the UK already living in houses without enough space, this is quickly becoming a less attractive option, especially when it comes to retrofit projects to combat issues with condensation and mould. 

James Erskine, Sales Manager of CorkSol, exclusive suppliers of SprayCork, discusses the rise of thin interior wall insulation solutions, and the benefits opting for these materials can provide over more traditional insulation methods. 

A report from the government revealed the estimated number of homes in England with damp and mould could be as many as 6.5 million households. 

This begs the question, why are so many UK homes not built to cope with the weather conditions we experience here? A general answer can be found in the 1900s, where England experienced several ‘housing booms’, growing the number of homes drastically in short periods of time. Examples of this can be seen after the Second World War when there was a big push to rebuild homes, and during Thatcher’s era with the introduction of the “Right to Buy” scheme, which allowed council tenants to purchase their homes at discounted prices.

Houses built in the UK before the 20th century were typically constructed with solid brick walls and little to no insulation, which isn’t effective for retaining heat. These homes were designed primarily to improve immediate living conditions, and were built to be breathable rather than airtight. In the past few decades a lot of regulations have come into play that have shifted focus to building envelopes and the importance of trying to achieve continuous insulation. 

British homes are often compact and built with limited interior space, which can discourage adding thick wall insulation or other weather-proofing measures that reduce space.

Newer construction methods have started to address these issues with better insulation, double or triple glazing, and airtight building techniques. But the UK’s diverse housing stock, especially with so many older buildings, means modernising for weather resilience is a gradual process and retrofitting older homes can be tricky, but not necessarily as challenging as demolishing existing buildings and starting anew. 

Additional interior wall insulation is usually specified if a house is suffering from cold internal temperatures, condensation on walls and damp or mould issues. The usual ‘go to’ solution most often seen in these scenarios would be replacing the plaster board with foam or foil backed panels. This process would involve clearing the inside of the house of belongings and people, arranging temporary housing and storage, removing existing plaster boards and replacing them with more insulating options. These boards that feature foil or foam will be thicker to account for the additional insulative materials, encroaching the space in the room. 

Alternatively, cavity wall insulation can be injected through the exterior wall by drilling holes into the outside of a structure and injecting expanding foam into the gap between walls. The holes in the mortar joints are then filled to restore the wall’s appearance, with the foam inside the cavity offering an additional layer to maintain inside temperatures. However, weather in the UK can cause multiple problems with rising damp and mould, and unfortunately, the addition of foam creates a bridge for the rain to soak through, and without the wall cavity, the gap is bridged. Where water would have previously run off into the cavity gap, it can now infiltrate the interior wall, causing a whole host of issues detrimental to health.

Thin interior wall insulation options are becoming more popular, saving space, downtime and improving U values. There are solutions on the market which require very little disruption to daily life, such as SprayCork from CorkSol. Not only is it no more than 6mm thick, it can be plastered over almost straight away, and, as long as the room is prepared properly, furniture and belongings can stay in the room – pulled away from the walls, and fixings like light switches, radiators, skirting boards and plug sockets can be taped up and left in situ.

As the exclusive UK distributor of SprayCork, CorkSol’s team has done commissioned research and found that SprayCork can prevent more than 30% of the heat you’re paying for being lost through the walls of your house, making it an ideal, space saving, convenient solution to temperature and condensation problems.