
MC2025 Abstracts & Papers
Session 1: Various Themes on People and Buildings
Understanding the Impact of Insulation on Moisture Content of Timber
Fatma Arslan
As retrofit strategies are accelerated to meet climate goals in the UK, floor insulation—particularly airtight materials such as spray foam—is gaining broader acceptance in the ageing housing stock. While effective for energy efficiency, the impact of spray foam on moisture-sensitive components like timber flooring remains underexplored in scientific literature. This study examines the early-stage effects of closed-cell spray foam insulation on the drying behaviour of saturated pine timbers under environmental conditions typical of UK homes.
Samples were soaked and dried under two scenarios in a controlled chamber (20°C/50% RH and 15°C/80% RH). Insulation was applied at staggered moisture content levels to simulate the partial enclosure process commonly seen in retrofit applications. Moisture changes were tracked using gravimetric weighing and surface-based measurements at multiple time points.
Insulation significantly delayed drying, especially when applied to timber with high moisture content. The key mechanisms involved include inhibiting vapour diffusion and decreasing surface exposure. After seven days, some insulated specimens retained 25–35% more moisture than uninsulated controls. These conditions increase the risk of biological degradation, including mould growth and wet rotting, which can undermine the durability of retrofitted buildings.
This research establishes critical benchmarks for safe insulation timing and supports healthier, longer-lasting interventions in moisture-prone building elements.
Keywords: timber flooring, spray foam insulation, moisture retention, drying behaviour, retrofit risk.
– Theme: Moisture Risk in Retrofit Insulation –

