PCA International Conference Moisture in Buildings

“Unintended consequences of retrofit works”

Colin King, BRE

Evidence• 2000 + properties visited

• 47 locations across the UK

• IR surveys

• Moisture measurement

• Visual Inspection

• Deconstruction of failed works

Energy savings less than anticipated

Ventilation

Insulation suitabilityPhysical aspects of agood process with reduced risk.

SystemicMaterials

Exposure and local climate When undertaking thermal improvements these should be

Considered at every

stage: planning,

procurement, design,

construction,

operation and

maintenance.

Assessment

Daylighting

Condition of Structure

Application

Heritage

Handover Information

Sources of Moisture

Restrictions to good design

On-site checks at key stages

Unintended Consequences

Unintended Consequences

Systemic

Subjective

Application

Assessment

Testing

Aesthetics

Heritage

Design

Surveying

Exposure &

Moisture

Skill levelSite

Controls

Application Methods• Use of expanding foam to apply the insulation

(proper adhesive lasting for 25years +)

• Applied in the rain

• No mechanical fixings / or preparation of substrate

Poor Design and Workmanship

Dry Rot

Water Ingress

Problems with Moisture

Timber Frame House

Built in 1967

Insulated in 2006

Wet /dry rot, structural failure 2012

- water ingress- poor detailing- failure of sealant- wet rot and dry

rot

Unintended Consequences• 126 Unintended Consequences

• 27 Significant risk to fabric and health

• Many moisture related

• Most avoidable, with proper surveys, changes to industry practice

• 12 Major changes to the way we do business.

Fundamental causes of problems with SWI

Some examples…

• Interstitial condensation

• Frost damage within walls

• Increased humidity, damp and mould growth

• Failure of internal finishes

• Reduction in air quality, stuffy and stale

• Rot and/ or insect attack on structural timbers

• Condensation/ mould at junctions/ connections

• Negative influence on neighbouring dwelling

Moisture Ventilation Bridging

Correct stakeholder intervention

Surveyor

Designer

Installer

Client

• Thorough survey – more than just ‘measuring up’

• Identify aspects that will require specific design consideration

• Manage expectations of occupants (space loss, practicalities of install)

• Address issues identified at survey; materials selection, detailing, etc.

• Ensure what is needed is priced

• Installers to follow detailing provided by designers

• No ‘ad hoc’ solutions on site• Pass ongoing maintenance/ fixing

requirements on to occupants

Summary• Quality surveys by experienced

surveyors who understand insulation

• Thorough design process

• Quality Control on Site

• Inspections at key stages

• Understand the specification

• Weather controls

Design out Unintended Consequences