CorkSol is proven as leading Thin Internal Wall Insulation solution

The Problem
Armed with the latest U-value testing equipment, and excited by the improved thermal performance data shown by the next generation SprayCork material in the lab, Corksol set out to assess the product’s thermal insulation performance as a Thin Internal Wall Insulation in a real-life situation.

The background to the testing was the UK Government’s March 2021 report on Thin Internal Wall Insulation (TIWI), which highlighted the potentially very large nationwide benefits for both energy efficiency and fuel poverty from high performance TIWI systems. The chosen test property was an 1890’s solid walled Yorkshire stone detached cottage in Halifax.

The small gas boiler struggled to keep the property warm in winter and mould and damp was evident on the walls, primarily in the corners and around the reveals of the French doors and windows. Drilling into the walls confirmed that there was no existing insulation, just plasterboard dot and dab fixed direct to the 300mm thick stone. The large dabs holding the plasterboard in place were cold to the touch, and an infra red camera confirmed clearly that they were acting as a strong cold bridge.

The landlord had experienced problems with penetrating damp in the gable wall, so had repointed this wall externally a year previously. Knowing that this wall was now fully dry, it made for a great test wall. The IR camera was used to determine the exact mounting point for the test rig, avoiding the cold bridge dabs which might skew the test.
The U-value test kit used, an ISO 98691:2014 approved Swiss system, requires three measurements - internal temperature, external temperature and heat flux - to be recorded every minute for at least 72 hours. The test requires internal and external temperatures to be significantly different, so carrying out the test in winter was ideal.

The wall was tested before application of SprayCork, and a U-value of 1.58W/m2K was obtained. This is a reasonably good performance for an uninsulated stone wall, but well within the expected range.

The Solution
SprayCork was spray applied directly to the existing plasterboard, across the whole internal surface of the exterior walls and around the window reveals. Application was in two layers giving an overall depth of 5-6mm. After drying, the walls were skimmed with 2mm of standard gypsum plaster, all in the same day.

Immediately there were signs that there were significant improvements in thermal performance. IR images showed a visible reduction in the cold bridges which had been caused by the plaster dabs and around the internal corners. This was visual confirmation of SprayCork’s effectiveness at increasing the surface temperature of the treated walls and so controlling condensation and mould.

After application, the U-value testing kit was re-mounted in the same spot as for the first test, under the same conditions. Four days later, the test was complete to ISO9869 standard, and the resulting U-value had improved to 1.10W/m2K.

The Outcome
By improving U-value from 1.58 to 1.10, SprayCork had caused a 30.4% reduction in heat loss through the wall. This is an incredible result for a product applied at only 6mm thick and is testament to the wonderful natural properties of cork, the world’s finest natural insulator. The additional improvements in condensation and mould control, along with creating a cosier feel for occupants, all driven by the increase in internal wall surface temperature, make for a compelling package of benefits.

The thin layer at which the product is applied makes it perfect for:
• Small rooms and tight spaces where thicker layers would cause unacceptable reduction in room size.
• Properties with historic internal architectural details, which should not be concealed behind thick layers of insulation for conservation reasons.
• Properties on a tight budget, who do not want the extra cost, time and hassle of repositioning services like electrical points, radiators etc.

The breathable, vapour-open nature of SprayCork makes it an ideal solution for traditional, solid walled properties whose walls were designed to breathe. SprayCork allows traditional buildings to continue operating as designed and making a significant impact on the UK’s journey towards Net Zero carbon by 2050.

www.corksoluk.com

Images © Corksol