Monitoring moisture in a historic brick wall following the application of internal thermal insulation

This paper monitors the in-situ moisture performance of a solid brick wall following the application of internal insulation using the timber dowel technique. Six internal insulations including thermal paint on lime plaster,... [ view full abstract ]

This paper monitors the in-situ moisture performance of a solid brick wall following the application of internal insulation using the timber dowel technique. Six internal insulations including thermal paint on lime plaster, aerogel (AG), cork-lime (CL), hemp-lime (HL), calcium silicate board (CSB) and PIR were applied to wall sections.
Improving the thermal performance of buildings reduces building operational energy and its associated negative impact on the environment. However, thermal insulation may increase moisture accumulation in walls undermining their long term durability and lowering their thermal efficiency. Currently, there is a lack of knowledge on the performance of traditional solid walls with respect to heat and moisture and the impact of internal insulation on their hygrothermal behaviour.
The changes in moisture recorded using timber dowels agreed with the moisture recorded using a commercial relative humidity (RH) probes. All the wall sections showed a reduction in moisture content over time as the construction moisture dried. The nature of the insulation significantly determined the wall moisture: after one year, the least vapour permeable and capillary active insulation (PIR, aerogel and paint) had higher moisture contents than the lime based insulation (LP, CL and HL). Moisture gradient across the wall (from the internal surface to wall mid-point) indicate that the lime based materials allow the dissipation of moisture towards the interior surface which is retarded by the low moisture permeability of the paint surface, aerogel and PIR.