For decades, the conservatory has been a staple of British housing. It represents a desire to bring the outdoors in, creating a light-filled sanctuary where we can enjoy our gardens while sheltered from the unpredictable weather. However, the traditional image of a conservatory—a structure entirely encased in glass or polycarbonate—often fails to live up to the dream. The vast majority of older conservatories suffer from the “Goldilocks” problem: they are rarely just right. Instead, they fluctuate between being an icebox in the winter and a greenhouse in the summer.
Fortunately, the technology behind home extensions has evolved dramatically. Homeowners are no longer restricted to thermally inefficient plastic boxes; they can now choose sophisticated architectural solutions that blend seamless design with high-performance insulation. Whether you are looking to retrofit a new roof onto an existing frame or build a completely new structure, industry leaders like Pure Conservatories offer a range of options, including modern orangeries, that solve the temperature regulation issues inherent in older designs. To make the right decision for your home, it is essential to understand the fundamental differences between solid and non-solid roofing systems.
Non-solid roofs are the defining feature of the traditional conservatory. Historically, these were the only options available if you wanted a “permitted development” structure that was exempt from strict building regulations.
Polycarbonate was the material of choice for the boom of conservatories built in the 1990s and early 2000s. It was lightweight, cheap, and let light in. However, it is arguably the worst performer in terms of thermal efficiency. Polycarbonate offers almost zero insulation, meaning any heat generated in your home escapes instantly through the roof in winter.
Beyond temperature, polycarbonate has significant acoustic drawbacks. Anyone who has sat in a polycarbonate conservatory during a heavy downpour knows the deafening roar it creates, making conversation or watching TV impossible. Visually, it can also look “cheap” and tends to discolor or gather moss over time, dating the property.
Modern glass roofs are a significant step up from polycarbonate. High-performance “solar control” glass can reflect a portion of the sun’s heat and retain some internal warmth. A glass roof offers aesthetically pleasing, crystal-clear views of the sky and maximizes natural light, which is excellent for mental well-being and plant growth.
However, even high-spec glass cannot compete with a solid wall or roof for insulation. In the height of summer, the solar gain (the heat entering the room) can still be overwhelming, creating a glare that makes screens unreadable. In winter, while better than plastic, glass still has a much higher U-value (thermal transmittance) than a standard roof, meaning your heating bills will inevitably be higher if you try to use the room as a daily living space.
In recent years, building regulations changed to allow solid roofs on conservatories, sparking a renovation revolution. A solid roof system typically replaces the glass or polycarbonate with lightweight tiles or slate, supported by a timber or aluminium framework filled with high-density insulation.
The primary difference between solid and non-solid is usability. A solid roof transforms a conservatory from a “seasonal room” into a permanent extension. The multiple layers of insulation (often achieving U-values as low as 0.15 to 0.18 W/m²K) mean the room retains heat just like your living room or kitchen.
This thermal regulation works both ways. In summer, the solid roof acts as a barrier against the sun, preventing the greenhouse effect. You can comfortably sit in the room in July without needing air conditioning, and in December without needing an electric heater running at full blast.
From the outside, a solid roof helps the extension blend in with the rest of the property. Rather than looking like a bolt-on afterthought, it looks like an integral part of the architecture, especially if the tiles match the main house.
From the inside, the difference is even more profound. A solid roof usually allows for a plastered, vaulted ceiling. This changes the acoustics entirely—the room sounds like a proper room, not a plastic tent. It also allows for the integration of spotlights, speakers, and pendant lighting, giving you far more interior design flexibility.
The main argument against solid roofs is the loss of light. If you replace a fully glazed roof with a solid one, the adjoining room (often a living room or kitchen) may become darker. This is where the concept of the “Orangery” or hybrid roofing systems comes into play.
An orangery is distinct from a conservatory in that it features more brickwork (solid walls) and typically a flat solid roof with a central glass lantern. This design is often considered the “gold standard” of home extensions. It provides the thermal mass and insulation of solid walls and a solid perimeter ceiling (perfect for downlights), while the central glass lantern floods the space with natural light from above.
Similarly, modern solid roof replacements can now include large glazed panels or Velux windows. This allows you to dictate exactly where the light falls, maintaining the brightness of a conservatory without the associated temperature extremes.
It is important to note that changing a translucent roof to a solid roof classifies as a “change of energy status” in the eyes of building control. Because a solid roof makes the room more habitable, the structure must comply with building regulations regarding structural integrity and thermal performance.
While this involves a bit more paperwork than simply replacing glass with glass, it adds significant value to the home. Estate agents and potential buyers generally view a solid-roof conservatory as functional square footage—a dining room, a home office, or a playroom. In contrast, an old polycarbonate conservatory is often viewed as a liability that will need money spent on it.
The choice between a solid and non-solid roof ultimately depends on how you intend to use the space.
For most modern homeowners, the shift is undeniably toward solid and hybrid solutions. The ability to reclaim that floor space for everyday living is worth the investment, turning a cold, unused glass box into the favorite room in the house.