Most home retrofits focus on insulation and new windows. Airtightness gets overlooked far more often, despite being just as important to how the finished home actually performs. This blog looks at why airtightness deserves the same attention as the more obvious retrofit measures.
In this blog, you’ll learn:
- Why air tightness is important in retrofits
- Challenges posed by air leaks in older homes
- Airtightness solutions for retrofit projects
- How to address ventilation concerns effectively
Why Airtightness Matters in Retrofit
When it comes to a home’s energy efficiency, airtightness is a key factor. Air tightness refers to a building’s ability to prevent air leakage through its envelope – walls, roofs and floors. When a home is airtight, the building envelope effectively prevents uncontrolled air leaks that would otherwise compromise energy savings and indoor comfort.
A retrofit assessment, typically carried out under PAS 2035, looks at a home’s construction, condition and existing performance to build a plan for improvement. A retrofit air test does something more specific: it finds the uncontrolled leaks themselves, so you can address them before they undermine the rest of your retrofit.
The Challenge: Leaks In Our Older Homes
Building regulations have evolved significantly and older homes often present challenges because of outdated construction standards. Built to vastly different standards than today’s, older homes typically leak far more air than modern ones. Traditional features like single-glazed windows and solid walls act as weak points, letting heat escape and driving up energy bills.
Over time, mastic seals around skirting boards and pipes can deteriorate, creating gaps for air to leak into wall cavities. Even a seemingly minor 2mm gap between skirting and floorboards adds up to thousands of millimetres of air leakage throughout a home.
Structural movement from years of wear and tear causes small cracks and faults in walls and ceilings too. These become gateways for uncontrolled air leaks – and in wet rooms, they can lead to serious damp and mould if left unaddressed.
Airtightness Solutions for Retrofit Projects
Implementing air tightness solutions during a retrofit project can significantly boost a home’s energy efficiency. Here’s how:
- Test after installation: a follow-up air test after retrofitting (conducted at the post-install stage) shows how much has genuinely improved and flags anything still outstanding. The final air tightness score can also feed into an EPC, often resulting in a better rating and a whole-band improvement.
- Get more from new systems: even the latest windows and heating systems can’t perform to their full capacity if existing air leaks go unaddressed.
- Use cost-effective measures: retrofitting for airtightness can be as simple as replacing deteriorated mastic seals, installing controlling membranes under leaky floors and replastering cracks.
Addressing Ventilation Concerns
Improving retrofit air tightness matters, but it has to go hand in hand with proper ventilation. Sealing up a home can expose an existing lack of controlled airflow that was previously masked by leakage, leading to moisture build-up and poor air quality.
To balance airtightness and ventilation:
- Mechanical Ventilation and Heat Recovery (MVHR) systems offer controlled airflow and recover heat from exhausted air.
- Trickle Vents allow for controlled air intake without compromising airtightness.
- Extractor Fans efficiently remove stale air from wet rooms.
- Openable Windows provide purge ventilation and fresh air when needed.
Because of this, balancing air tightness with proper ventilation is essential to avoid problems like damp and mould – a whole house ventilation survey should assess both passive and active routes.
Sometimes that balance is the whole story. Across 28 retirement flats for Anchor, borescope surveys found the reported damp had nothing to do with the building’s structure at all – inadequate ventilation was the real cause, turning what looked like an expensive fabric problem into a targeted ventilation fix.
What’s Next?
Retrofit air tightness isn’t a finishing touch – it’s what determines whether the rest of the retrofit actually delivers. Get it right, and energy efficiency, running costs and comfort all improve together.
For professional air tightness testing on your retrofit project, contact our experts today.
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