Rotten Joists

I recently was speaking to a property developer about rotten joists that had happened due to energy improvement works.

What had happened, was that the rooms had been well insulated with Internal Wall Insulation, but the property was a solid stone external wall built circa 1850-80. Under the floorboards, no insulation had been put in, so all the moisture in the air was trying to escape under the floorboards and out of the stone wall, through a strong thermal bridge, and that moisture condensed and made the joists wet and they rotted away.

In all honesty, they were probable rotting for many decades, and weren’t seen in the initial renovation, however the additional internal wall insulation wouldn’t have helped and probably exacerbated the situation.

When you’re thinking about internal wall insulation, or any energy efficiency measures, bringing in a consultant can help you avoid problems like this, or the use of a thermal imaging camera can help understand what additional insulation measures are needed!