The importance of using thermal break materials with the right compressive strength

The stronger the better – a phrase that makes sense when it comes to construction and building projects. Every element should be the strongest it can be to withstand the weight and pressures of the rest of the build, but should this always be the case? The team at Armatherm is often approached by architects and specifiers looking for thermal breaks in the highest compressive strength available, no matter what the application is.

To put it in simple terms, this is the wrong approach. Thermal breaks prevent thermal bridging and reduce heat loss, depending on the products, the qualities differ. A general rule of thumb is the lower the compressive strength, the higher the thermal isolation effectiveness. With energy standards ever increasing in a bid to achieve net zero energy standards, it’s more important than ever that the industry does not overcompensate with compressive strength for the application.

Structural thermal breaks are a key player in the construction of energy efficient buildings that need to meet strict energy codes. The different locations where thermal breaks are incorporated can range from column bases and balcony connections right through to cladding and masonry shelf angles, with each requiring very different properties in terms of load bearing capacity.

For example, internal steel columns will traditionally extend through the building envelope floor slab and insulation at their base. In low temperature buildings, such as cold storage units, this creates a bridge for energy to transfer through. This is also present within support floors or roof overhangs.

Looking at balcony connections specifically, these are locations that experience both high levels of tension and compression. The structural column has to bear the weight of the structural beam at a right angle, which puts pressure on the whole of the structure. To thermally isolate this connection, a thermal break should be included between the two pieces of steel, with the bolts running directly through. This creates tension throughout the top half of the application, and compression throughout the bottom where the cantilever joins. Compressive strength is important for these locations, as the ability for the material to withstand loads that reduce the size of that material, or structural element, when applied is imperative.

It’s a common misconception that the stronger the thermal break material, the better it will perform in all applications. This is not the case. The more dense the thermal break material, the stronger it is, which sounds like a positive scenario, but this makes it less effective as an insulator.

Thermal breaks with a lower compressive strength capacity tend not to absorb water and have a very limited creep under load. Because of this, energy lost from thermal bridging is vastly reduced. This is ideal for connections such as column bases. As mentioned previously, the lower the compressive strength of the material, the higher the R value. So, finding the best balance here is key. The compressive strength must be sufficient, but not overcompensated for, so that the R value is preserved as much as possible, to improve the energy efficiency of a building and meet strict regulations.

A structural thermal break’s primary objective is to reduce the cold bridge within the building envelope, but they must also maintain the structural integrity of the connection. In a balcony situation for example, the steel to steel location would require a thermal break such as the Armatherm FRR range.

The compressive strength can be calculated by advising the load the thermal break will be exposed to, along the length x width of the thermal break which would then be mirrored to the size of the end plate, faceplate or column base details (connection design).

It’s common for structural thermal breaks suppliers to cater for high compressive strength only, due to a limited range of material. This again results in materials with a high compressive strength being used in applications that do not require it. Unfortunately this means the applications could potentially be made more thermally efficient by using a thermal break with lower compressive strength.

Armatherm has developed a product range that caters for all requirements and applications. With solutions that have a compressive strength at the lower end, as well as the higher end of the spectrum. This means we can supply the right material for the specific application and project goals.

Another factor that suffers with overcompensating on compressive strength, is budget. Materials with higher compressive strength are usually more expensive. So when these materials are used for applications which do not require it, the budget is wasted. At Armatherm, we are dedicated to ensuring you have the correct materials for the exact project you’re working on. This is why we have developed a diverse range of products over the years, meaning we are the only thermal breaks manufacturer globally to offer such a wide variety of products to the market.

Armatherm has a dedicated support team, detailed documentation and online learning resources, to help advise on the most appropriate material for your project. If you would like to learn more, get in touch with one of our consultants today.