Thermal Efficiency vs. Strength: Navigating the Dilemma of Thermal Breaks

With a lot of construction projects it is thought that the stronger the building elements, the stronger the project. Each material should be the strongest it can be to withstand the pressures and the weight of the rest of the build, But are there other factors that should be considered? Could there be scenarios where the strength is overcompensated, at the detriment of other important standards. The team at Armatherm has experienced these questions numerous times, with customers looking for the highest possible compressive strength no matter what the project or application is.

We appreciate the importance of safety factors when engineering buildings, but there is a point at which more is not necessarily better. Because inserting thermal breaks into structural connections is becoming standard practice, choosing the right strength and density of thermal breaks is important to achieve design goals. Armatherm has several thermal break materials to choose from to help with this.

Structural thermal breaks are really important in the battle to create energy efficient buildings. They prevent thermal bridging and reduce heat loss, and the general rule of thumb when it comes to a thermal break’s compressive strength is the lower the compressive strength, the higher the thermal isolation effectiveness.

The number of locations that benefit from thermal breaks is vast, ranging from column bases and balcony connections right through to masonry shelf angles and cladding – each one requiring different properties when it comes to load bearing capacities.

Looking at internal steel columns as an example, these traditionally extend through the building envelope floor slab and insulation at their base. In buildings that need to hold low temperatures (such as cold storage facilities) this can create a bridge for energy to transfer through. This can also be seen with floor or roof overhangs. The applications require relatively low compressive strength so it’s a prime example of a scenario where strength can be sacrificed for thermal performance.

Another key example is balcony connections. These locations experience both high levels of compression and tension. The structural column has to bear the weight of the structural beam at a 90 degree angle which puts pressure on the structure as a whole. In order to thermally isolate this connection, thermal breaks should be included between the two pieces of steel with bolts running directly through. This style of attachment results in tension throughout the top half of the application, and compression at the bottom when the cantilever joins. It is at these locations where compressive strength is important, as the ability of the material to withstand loads that reduce the size of the structural elements when applied is imperative, therefore thermal performance must be sacrificed to meet the required strength properties.

Often, engineers will factor in an additional margin, on top of the quoted figures from testing results. The additional strength properties act as a safety net, which is the backbone of all structures and their safety levels. In the planning phase of all structures, engineers determine the required overload from any object to remain safe in the event of discrepancies. Whilst this is the proper course of action to avoid safety concerns – in the thermal break industry, it must also be considered, the more dense the material, the less effective it performs as an insulator.

Typically, any thermal break material with lower compressive strength capacity tends not to absorb water and has very limited creep under load. Because of this, energy lost via thermal bridges can be massively reduced. The lower the compressive strength of a material the higher the R value, and so finding the best balance between insulation and strength is key. The compressive strength must be sufficient enough to withstand the loads of the connections, but not so overcompensated as to be detrimental to the R value which is needed to improve efficiency and meet strict regulations.

Another factor that suffers when opting to overcompensate with compressive strength, is the project budget. The thermal break materials with higher compressive strength are typically more expensive, so when these materials are utilized for a project which doesn’t require them, budget can be wasted. The team at Armatherm is dedicated to ensuring the correct materials are selected from the diverse range we provide. We are the only thermal bridging solutions manufacturer globally to offer such a variety of products on the market.

As the industry strives for net-zero carbon emissions, there’s a lot of discussion in the design community surrounding structural connections with thermal breaks. Many connections at balconies, parapets, canopies, column bases and other connections that pierce the building envelope create significant energy loss if they don’t incorporate thermal breaks.

In response to the various stresses and conditions to account for, Armatherm set out to produce several structural, insulating products that can be cut to size and shape, and drilled as needed to address the various thermal bridging situations, including thermal break products that can hold up to tens of thousands of pounds of pressure per square inch. Additionally, we also produce lighter, higher-R value products that can withstand hundreds of psi and may be the better choice for thermal performance.

Armatherm has created a range of products that caters for the majority of requirements and applications. The solutions offer compressive strength at the higher and lower ends of the spectrum, meaning the right material can be specified for specific applications and meet the structural and insulating goals of the project.