Concern & action: Trapped/accumulated moisture

Moisture, both as a liquid and a vapour, becoming trapped and possibly accumulating within building fabric as a result of changing either fabric or ventilation conditions. For instance, where there is rising damp in a wall or high levels of moisture within a solid floor, the application of vapour closed materials or reduced whole house ventilation could result in moisture related problems (e.g. timber decay, mould growth)

Suggested actions

Before Implementation

Prior to refurbishment install moisture monitoring (e.g. through wall or other fabric element) to establish moisture profile of structure and cause of any existing problems. Check fabric for any water leaks. Ensure any existing dampness is resolved before proceeding with measure. Define specific site Exposure conditions for different orientations. Understand the properties of existing materials properties in relation to moisture (vapour permeability, hygroscopicity and capillarity).

During implementation

Ensure the technical properties of any proposed new materials particularly in relation to moisture (vapour permeability, hygroscopicity and capillarity) and behaviour of these in relation to existing fabric are clearly understood. Choose appropriately breathable insulating materials. Develop robust details that avoid trapping moisture in instances of failure e.g. broken gutter, overflowing bath.

After implementation

Monitore moisture at vulnerable locations and report findings



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Halliday, S., (Gaia Research)

Solid Wall Insulation in Scotland: Exploring barriers, solutions and new approaches (2012)

Warmer Bath: A guide to improving the energy efficiency of traditional homes in the city of Bath (2011)
Bath Preservation Trust & Centre for Sustainable Energy

The Performance of Traditional Buildings: the SPAB Building Performance Survey 2013 (2013)
Rye, C, Scott C & Hubbard, D.

Energy Efficiency And Historic Buildings - Application of Part L of the Building Regulations to historic and traditionally constructed buildings (2011)
English Heritage

Improving Energy Efficiency in Traditional Buildings
Historic Scotland

Breathability: The Key to Building Performance (2005)
May, N.

Guidelines to avoid mould growth in buildings, Advanced Buildings Energy Research, 3, pp. 221-236. (2009)
Altamirano-Medina H., Mumovic D., Davies M., Ridley I. and Oreszczyn T.

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A Short Paper on the Conventions and Standards that govern the understanding of moisture risk in traditional buildings. (2012)
Rye C and MayN

A Short Paper on Internal Wall Insulation (2012)
May N

Conversion of Traditional Buildings Part 2 - sections 3 Enviroment & 6 Energy (2007)
Ed. Dennis Urquhart, Historic Scotland

Insulating thatched roofs (2012)
English Heritage

Early cavity walls (2012)
English Heritage