What insulation is best for Victorian and Edwardian houses?
- Tom Collings
- 2 days ago
- 3 min read
Updated: 17 hours ago
Victorian and Edwardian properties are a distinctive part of the British housing stock. They are celebrated for their charm, spaciousness, and sturdy construction, offering a sense of history and unique architectural details that are difficult to replicate in newer builds.
However, these traditional houses are notorious for being draughty and difficult to keep warm. Insulating their floors, which are so often draughty, presents several unique challenges rooted in both their construction methods and the need to preserve their historic features.
What’s Particular About Victorian and Edwardian Properties?
Suspended Timber Floors
Most Victorian and Edwardian homes have suspended timber floors, where floorboards are laid over wooden joists with a ventilated void beneath. This design has worked very well for over a century to keep the timber dry by allowing airflow. However, it was not designed to retain heat.
Solid Walls
These houses typically have solid brick walls, not cavity walls, making wall insulation more complex and shifting the focus to floors and roofs for thermal upgrades.
Ventilation and Breathability
The original design prioritised breathability and moisture management to prevent damp, not airtightness or insulation which is important in modern British house design.
Historic Features
Many properties are listed or in conservation areas, restricting alterations and requiring sensitive approaches to preserve period details like skirting, cornices, and original floorboards.
Key Challenges and the Retrovive solution
1. Thermal performance
Current UK Building Regulations (Part L) require floors in existing homes to achieve a "U-value of at least 0.25 W/m²K" in England when renovating a floor.
In simple terms, this means that when you insulate or replace a floor in an existing home, the floor must be good enough at keeping heat in so that only a small amount escapes.
Retrovive achieves this, usually within the depth of the existing Victorian or Edwardian floor joists. We install a membrane below the joists that holds a certain depth of cellulose fibre insulation between it and the floorboards.
As the insulation is blown-in under pressure to tightly fill every corner, this gives the important additional benefit of preventing cold draughts from below.
2. Access and Disruption
Insulating under the floor usually means lifting floorboards, which can be time-consuming and risks damaging the original boards, especially if they are brittle or have been nailed down repeatedly over the decades.
In some cases, access may be possible from below (e.g., via a cellar), but many homes lack this, making the job more invasive.
Retrovive was designed specifically to reduce the need to lift the whole floor - we only need to raise a few boards to install our high-performance insulation beneath. We take great care to avoid damage and keep the attractive look of exposed floorboards.
3. Maintaining Ventilation
The underfloor void must remain well-ventilated to prevent condensation and timber decay. Blocking air bricks or vents can lead to damp and rot issues, which could be serious if left untreated. We have special techniques to duct the airflow down underneath the floor to keep the ventilation working properly.
Balancing insulation with adequate airflow is critical. Over-sealing can trap moisture, while under-sealing reduces insulation effectiveness.
Retrovive's cellulose fibre insulation is held up against the underside of the floor with our unique breathable membrane and hanger system, keeping the important ventilation airgap below the insulation.
4. Moisture Control
Victorian floors were designed to "breathe." Using non-breathable insulation or membranes could trap moisture, leading to condensation, mould, and timber decay.
Materials must be chosen carefully. That's why natural, vapour-permeable options like cellulose fibre are recommended.
Retrovive's cellulose-fibre insulation and supporting membrane are breathable, for a dry and healthy home. Our insulation is also fire-resistant and deters mice and other pests!
Read more: Breathable membranes and moisture control
Retrovive underfloor insulation is designed specially for Victorian and Edwardian homes
Insulating under the floors of Victorian and Edwardian houses can be hugely beneficial but demands a careful, tailored approach.
The way that Victorian and Edwardian houses are constructed, with suspended timber floors, solid walls, and a need for breathability, means standard modern solutions often aren't appropriate.
Retrovive offers modern levels of thermal performance while minimising disruption to period properties and carefully controlling moisture and ventilation for a more comfortable, healthy home.
