Conservatory Roof Types: Which Is Right for Your Home? 

The reason most conservatories become unusable in July and cold by October has very little to do with how well the house is heated. It comes down to the roof. You will spend hours choosing between Victorian and Edwardian shapes, between uPVC and aluminium frames, between bi-fold doors and sliding ones. That all matters. But the conservatory roof types available to you (polycarbonate, solar-control glass, and solid tiled) vary so widely in thermal performance that the choice determines whether the space is usable in every month of the year, or only some of them. Get it wrong and you have built an expensive glazed room you avoid in summer and cannot heat in winter.

This guide covers the three main conservatory roof types, what they actually deliver in thermal terms, how your conservatory's orientation should shape the specification, and what the 2022 Building Regulations changes mean in practice. We install conservatories across Surrey, Hampshire, Berkshire, West Sussex, and South-West London, and we survey every property before making a roof recommendation. The orientation, the shade pattern, the planned use of the space, and your priorities for natural light all bear on the answer. What follows is the framework we work through.

Why conservatory roof type matters more than almost any other decision

A conservatory roof operates under conditions that no other part of the house faces. In summer, it receives direct solar radiation for hours at a time. In winter, it is the largest single surface through which the space loses heat. A well-insulated wall loses heat slowly. A poorly specified roof loses it quickly, because warm air rises and the roof is where it meets the cold.

The physics behind the overheating problem is not complicated. Solar radiation passes through glass and polycarbonate and warms the surfaces inside. Those surfaces re-radiate heat at a longer wavelength that the glazing cannot transmit back out as easily. The result is a greenhouse effect: the conservatory absorbs heat faster than it can release it. A polycarbonate roof makes this worse because it has almost no thermal mass and very poor insulating properties. It is genuinely one of the worst materials you could put on a roof you want to use in July.

In winter, the same thin roof surface conducts heat from the warm interior to the cold outside air. There is no meaningful insulation to slow the transfer. The space cools as fast as you can heat it. Most homeowners who complain that their conservatory is too expensive to heat are not dealing with a heating problem. They are dealing with a roof problem. The two are different, and only one of them is fixed by adding another radiator.

We start every conservatory conversation with orientation and use because those are the variables that determine what the roof needs to do. A south-facing conservatory in Farnham will receive direct afternoon sun and will overheat more severely than a north-facing one in Guildford that receives little direct sunlight. The roof specification needs to reflect that difference. A polycarbonate roof that is borderline adequate on a north-facing structure is simply wrong on a south-facing one.

The three conservatory roof types and what they actually deliver

There are three main roof types in use in UK residential conservatories: polycarbonate, glass (including solar-control glass), and solid tiled. Each has a different thermal profile, a different effect on natural light, and a different appropriate use case. We are not tied to any single manufacturer or system, so the recommendation we make starts with the property and the use case, not with what happens to be available.

Polycarbonate roofs are the least expensive option and historically the most common. A standard 25mm polycarbonate panel is a poor insulator. U-value comparison data published by Leka Systems puts polycarbonate at 1.6 to 2.1 W/m²K. For context, the lower the U-value, the better the insulation. That puts polycarbonate at roughly the performance level of single glazing. It also admits solar gain without resistance. We do not recommend polycarbonate for a conservatory that is going to be used as a room. The only situation where it is arguably adequate is a north or east-facing structure used as a utility or hobby space where the occupants accept seasonal limits on comfort. If the conservatory is going to function as a sitting room, a dining space, or an extension of the main living area, polycarbonate will let you down before summer is over.

Solar-control glass roofs are the most common upgrade choice and, for most Surrey and Hampshire homes, the most practical one. A solar-control glass unit typically achieves a U-value of 0.5 to 1.0 W/m²K, compared to 1.5 to 2.3 W/m²K for standard double glazing. That is a meaningful improvement in both directions: less heat lost in winter, less solar gain admitted in summer. The technology behind it is a microscopically thin metal oxide coating on the glass surface. In summer, it reflects solar radiation away. In winter, it reflects internally generated heat back into the room. The result is a roof that works in both seasons rather than just one. Solar-control glass also retains the glazed character that most people picture when they plan a conservatory. If you want a space that feels light, open, and connected to the garden, this is usually where we land.

Solid tiled roofs offer the best insulation, and if the conservatory is intended as a fully integrated room rather than a glazed extension, this is the specification that makes most sense. A quality solid tiled roof typically achieves a U-value of 0.15 to 0.30 W/m²K. That is considerably better than any glass option. The roof is constructed from insulated panels with lightweight tiles on top, with rooflights or skylights added to bring in light. The conservatory feels like part of the house rather than an attachment. It stays warm in winter without continuous heating, and it does not overheat regardless of orientation. The honest trade-off is natural light. Even with rooflights, a tiled roof reduces brightness significantly compared to a fully glazed structure. For homeowners who want to use the space as a bedroom, a study, or somewhere the garden connection matters less than the room quality, a tiled roof is usually the stronger long-term choice.

U-value data: Leka Systems, published April 2023. Lower U-value indicates better thermal insulation.

How the direction your conservatory faces changes what you need

Orientation is the variable that no comparison table addresses, and it is the one that most often changes our recommendation between otherwise identical conservatories.

A south-facing conservatory receives direct sunlight from mid-morning through to late afternoon. In summer, the solar gain is substantial and sustained. For this orientation, the minimum viable roof specification for a living space is solar-control glass with a low g-value. We would not specify polycarbonate on a south-facing conservatory intended for regular use. It will be unusable for weeks at a time in high summer, and no amount of blinds or fans changes the underlying problem. A solid tiled roof eliminates the overheating issue entirely but removes the light and the garden connection that often motivates the project.

A west-facing conservatory receives its strongest sun in the afternoon and evening. The overheating risk is similar to south-facing, though it peaks later in the day. Solar-control glass is usually the right call. The evening light on a west-facing conservatory is often the reason the homeowner wanted it in the first place. A tiled roof removes that benefit. If the space is going to be used most in the evenings, solar-control glass usually serves the project better.

A north-facing conservatory receives little direct sunlight for most of the year. The overheating risk is much lower. The primary thermal challenge is heat loss in winter rather than summer gain. For a north-facing conservatory, standard double-glazed glass may be adequate, though solar-control glass still performs meaningfully better. A tiled roof is appropriate if the space is to be used as a room rather than a garden-facing sitting area, since the light sacrifice is less significant on a north-facing orientation where the natural light is already limited.

An east-facing conservatory receives morning sun. The overheating problem is real but less severe than south or west facing, as the sun moves away from the structure by early afternoon. Solar-control glass is usually appropriate. The morning light is a genuine asset that a tiled roof would reduce.

Shade also matters. A south-facing conservatory sheltered by a large established tree has a different solar gain profile from an exposed south-facing structure. This is one reason we survey the property before recommending a specification. The orientation is not the only variable. We look at what is shading the structure, what time of day the shade falls, whether the main use of the space is morning or evening, and what the buyer's light priorities are. If you are considering our conservatory installations in Surrey and Hampshire, an early conversation about how the space faces and how you plan to use it will save you making a specification decision you would later want to revisit.

What to ask about solar-control glass before you commit

Solar-control glass covers a wide range of products with genuinely different performance levels. The term describes a category, not a specification. Two quotes that both say "solar-control glass" may be for products with meaningfully different U-values and g-values. We have seen homeowners accept a solar-control glass roof that barely outperforms standard double glazing because no one explained the numbers. This section gives you the questions to ask before you accept any glass roof specification.

The first is the U-value, which measures heat loss. For a glass conservatory roof intended for year-round use, look for a U-value of 1.0 W/m²K or below. Standard double-glazed units often fall between 1.5 and 2.3 W/m²K. A unit described as solar-control glass but specified with a U-value above 1.0 W/m²K is not performing significantly better than standard glazing for winter heat retention.

The second is the g-value, also called the solar heat gain coefficient. This is the proportion of solar energy that the glass transmits into the room. A g-value of 0.30 means 30 percent of solar energy passes through. For south or west-facing conservatories, you want a lower g-value to limit summer overheating. For north or east-facing structures, a slightly higher g-value can be beneficial in winter because some solar gain is useful. Ask your installer for the g-value of the specific product they are specifying, and ask them whether it is appropriate for your orientation.

The third is the light transmission percentage. Solar-control coatings reduce visible light transmission to varying degrees. A product that blocks a large proportion of solar heat may also noticeably reduce the brightness of the room in winter. There is a genuine trade-off here, and the right balance depends on your priorities. Ask for the light transmission percentage of the specified product.

Any reputable installer should be able to provide these figures from the product's technical datasheet. If you receive a quote that specifies solar-control glass but the installer cannot tell you the U-value, the g-value, or the light transmission, you have not received a specification. You have received a description of a material category. Those are different things, and the gap between them is often where the disappointment lives.

What the 2022 Building Regulations changes mean for your conservatory

There is genuine confusion about what the 2022 changes to Building Regulations mean for conservatories. Some homeowners have heard that conservatories have been restricted or banned. They have not. What changed is the thermal standard required for new conservatories on new-build homes, and the U-value required for replacement solid roofs on existing conservatories.

Approved Document O (overheating) on the Planning Portal took effect on 15 June 2022. It applies to new residential buildings only. If a conservatory is included as part of a new-build home, it must prevent unwanted solar gain through high-performance solar-control glazing and must provide adequate ventilation. This is not a ban on conservatories. It is a requirement to build them properly. A conservatory on a new-build home that meets Part O is one that works all year round. That is the outcome the regulation exists to produce.

Conservatories added to existing homes are generally exempt from Part O, provided they meet the standard exemption criteria: under 30 square metres, built at ground level, with a mainly transparent or translucent roof, thermally separated from the main house by a door or wall, and with independently controlled heating. Most residential conservatory additions fall within these criteria.

Approved Document L, which covers energy conservation, sets the U-value requirements for replacement conservatory roofs. For solid replacement roofs, the current target is 0.15 W/m²K, a figure confirmed in the government's Approved Documents index on gov.uk. If you are replacing an existing polycarbonate or glass roof with a solid tiled system, Building Regulations approval will be required to confirm the new structure meets these requirements and that the existing frame and foundations can carry the additional weight.

The practical implication for most homeowners is this: if you are adding a new conservatory to an existing home, you are unlikely to need Building Regulations approval for the conservatory itself, provided it meets the exemption criteria. If you are replacing an existing roof with a solid tiled system, Building Control sign-off is typically required because the new structure changes the thermal envelope. Chartwell is FENSA-registered for applicable replacement window and door work. Conservatories and solid roof replacements can fall under different Building Regulations routes depending on the specification. At survey stage, we will explain whether your project can proceed under the standard conservatory exemption, whether any glazing work is covered by a competent person scheme, or whether formal Building Control approval is required. We advise on this at survey stage, before any commitment.

The rest of the specification: frames, glazed walls, and ventilation

The roof is the most important thermal decision in a conservatory, but it does not operate in isolation. The frame material, the glazed side panels, and the doors into the garden all contribute to the same thermal envelope. A solar-control glass roof on poorly insulated side glazing is a contradictory specification. The roof does its job and the panels undo it.

Frame material matters through what is called cold bridging. Standard aluminium conducts heat efficiently, which in a frame means it conducts cold from outside into the room during winter, creating cold spots at the perimeter of each glazed panel. Modern aluminium frames include a thermal break: an insulating section between the inner and outer profiles that eliminates most of that problem. We install aluminium, uPVC, and timber frames across our conservatory projects, and the right choice depends on the property and the aesthetic. For a contemporary Surrey extension, aluminium with a thermal break is usually the right frame. For a period cottage, timber is typically the better fit. For a budget-conscious lean-to, uPVC multi-chamber profiles perform well. Each material has its context, and part of our job at survey stage is matching the frame specification to the property rather than defaulting to whatever is easiest to source.

Side glazing and wall panels are part of the same thermal envelope as the roof. A solar-control glass roof above single-glazed side panels is a poor specification. The side panels should be double-glazed as a minimum, with U-values consistent with the rest of the structure. This is worth checking explicitly in any quotation, because the roof specification tends to receive attention while the wall panels are sometimes treated as an afterthought.

Glazed doors into the garden are where we see the most inconsistency. A conservatory with a well-specified roof and high-quality frames is undermined by bi-fold or sliding doors with inadequate weather seals or single-glazed panels. Check the U-value and seal quality of any door panels in the quotation. They are part of the structure and should be specified to the same standard as the rest of it.

Ventilation is a separate consideration. A well-sealed, well-insulated conservatory with no ventilation strategy will accumulate condensation and create air quality problems. Openable roof lights, casement windows with trickle vents, or ventilation in the door frames all provide the air exchange that prevents these problems. Our wraparound conservatories and larger structures benefit most from a ventilation plan that considers cross-flow and the position of openable panels relative to the direction of prevailing wind.