42043
14 April 2025 

Draught proofing in historic buildings

Out of 30 million homes in the UK, 6 million were built before 1919. Many remain unimproved, featuring little or no draught-proofing, single-glazed windows, minimal loft insulation, solid walls and uninsulated floors.

Effective draught proofing in traditionally constructed buildings require a careful balance between retaining ventilation and minimising heat loss. Unlike modern buildings, which prioritise airtightness, older buildings have depended on air movement (draughts) to prevent damp and maintain indoor air quality. Building conservation professionals must navigate these complexities to ensure energy efficiency improvements do not compromise a building’s health.

Proper ventilation is crucial for maintaining indoor air quality, preventing moisture buildup, and ensuring occupant comfort in all buildings. Many older structures were designed with natural airflow in mind, incorporating chimneys, timber windows, and wall vents to promote circulation. As buildings have been modernised with insulation, register plates and sealed windows, these passive ventilation mechanisms have often been restricted, leading to condensation, mould growth, and poor air quality.

Natural ventilation in older buildings typically occurs through gaps in walls (around pipes and cables), around windows and doors, through floors and skirtings, and through passive systems like stack effect, where warm air rises and escapes through upper openings while drawing in cooler air from lower levels. Understanding these airflow patterns is essential when renovating or retrofitting an older building, as blocking or altering these pathways without compensating with controlled ventilation can lead to unintended consequences such as high humidity or stale, polluted air.

Traditional construction materials such as lime plaster, timber beams and masonry walls rely on ‘breathability’ to manage moisture levels effectively. Breathability technically refers to the movement of air through building fabric but is used as a shorthand for water permeability or openness to the movement of water vapour. Inappropriately applied modern materials, such as cement-based renders or synthetic paints and sealants, can prevent this natural movement, trap moisture and accelerate decay.

While maintaining healthy airflow (ventilation) is important, excessive draughts (infiltration) can lead to significant heat loss, discomfort, and increased heating bills. The challenge for conservation specialists is determining where background infiltration is beneficial and where it should be controlled.

Draught proofing in period buildings is a specialist task that requires careful planning and an understanding of traditional construction methods. Retrofitting energy efficiency measures without compromising the building's integrity is challenging and working with an experienced company like Mitchell & Dickinson is highly recommended.

A contractor with expertise in historic buildings will be able to identify key areas of heat loss quickly. Their knowledge ensures that the most appropriate solutions are applied, balancing modern energy efficiency standards with traditional building materials and techniques. Conservation specialists will also be familiar with the nuances of listed buildings and conservation areas, ensuring that all work is compliant with regulations and does not detract from the historic character of the property.

An experienced team can provide tailored recommendations, from selecting the right type of secondary glazing to advising on underfloor insulation techniques that maintain breathability. With professional input, homeowners and conservation professionals can significantly reduce heat loss while preserving the integrity of the building.

For more information on Mitchell & Dickinson, call 01237 871 127 or visit www.mitchellanddickinson.co.uk   

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With compliments:

Taylor Alden
media@tayloralden.co.uk