If your conservatory roof is tired, the choice that comes up first is whether to stay with polycarbonate or move to glass. Both are light-transmitting, and both have a loyal following. Neither is right for every room.
Polycarbonate comes as flat sheets, often with hollow channels inside them, carried on glazing bars. It is light to handle and gentle on the frame. Glass comes as sealed double-glazed units, heavier and sold in panes that sit in the same kind of bars. A fitter can often swap one for the other on the existing frame, though the bars, seals and weight all need checking.
The comparison below keeps to what an owner can feel and what a roofer can measure: how warm the room is, how loud the rain is, how bright it stays, how many years to expect and what is behind the price ranges you will see online. A third route, a solid roof, is covered in our guides on tiled and lantern roofs. This guide sits under our conservatory roof replacement service and is meant for the decision stage.
Which one keeps the room comfortable
Both materials let in the sun, so both can warm a south-facing room beyond comfort. What differs is how well they hold heat in once the sun goes, and how much of the sun's energy they let through.
Polycarbonate
Multiwall sheets trap still air inside their channels, which gives some insulation, and the thicker the sheet, the more it holds back. Thin or single-skin sheets give little. Many older conservatory roofs were fitted with a thin sheet to save weight, which explains the familiar pattern of a baking room in July and a cold one in January.
Glass
The gap between its panes is why a sealed double-glazed unit holds heat in better than a thin sheet does. A unit with a special coating can reflect part of the sun's heat as well, which cools the room in summer. Our answer on whether solar control glass is worth it goes through when the coating pays off.
Matching the material to the room
Aspect decides a lot. A room that faces south or west takes heat in the afternoon and gains most from a coated unit. A north-facing room has the opposite problem, and polycarbonate there often feels cold rather than hot. Our survey notes which way the roof faces, how large it is and what shades or blinds you already use, so that advice comes from your own room.
Living with the result
Blinds, roof vents and a ceiling fan can take the edge off either material, and they are worth adding whichever you choose. They are cheaper than a new roof, though, and they do not cure a roof that was wrongly specified. If you only use the room in spring and autumn, a modest improvement may be all you need. If it is an everyday dining or work space, the covering deserves more thought.
Rain, hail and the noise overhead
Noise is the complaint people raise second, after temperature. Rain on thin plastic sheets can be loud, and a thundery downpour can make conversation hard.
Why polycarbonate drums
A thin sheet vibrates like a drum skin when drops hit it, and the hollow channels amplify rather than absorb the sound. Thicker sheets and a good seal between sheet and bar reduce it, but they cannot match the stiffness of glass.
How glass behaves
A pane of glass in a rigid frame is quieter, since the glass is heavy and the gap between panes damps the vibration. Rain still makes a sound, but it is softer, and hail is less alarming. Our answer on why a conservatory roof is noisy in the rain sets out the causes and fixes.
Hail and impact
Polycarbonate is tough and flexes where glass could crack, which is one reason it was so popular. Glass for an overhead position is a safety grade, and your supplier should state which type goes into the roof. Ask for the glazing data sheet before ordering, and keep it with the other paperwork for the job.
Reading the symptoms
If your roof is noisy and leaks as well, the noise may be a loose sheet or a failing bar seal and not the material at all. We can often tell from a ladder and a torch. Rattling in wind points to loose fixings, a steady drip points to a seal, and a roar in heavy rain points to the sheet itself.
Quieting an existing roof
Sometimes the sheets can stay. Fitting foam strips under the bars, replacing worn gaskets and adding a second layer to the underside can soften the sound, though the improvement is modest. Where the noise is the main complaint and the roof has nearly reached the end of its service, a quieter covering is a better use of the money than another patch.
Light, glare and privacy
Glass is clearer. Polycarbonate comes in clear, opal and bronze finishes, and even the clearest sheet has a slight haze, so the view of the sky is softer. For a room where you want sunlight and a view of the clouds, glass wins. For a room where glare is the problem, a tinted sheet or a coated unit will help.
Colour, tint and coatings
A bronze or opal sheet cuts glare and heat at the cost of daylight. A coated unit can be near-clear and still reduce heat gain, but it can show a slight colour cast. Hold a sample against the sky before you choose, because a small colour difference looks bigger across a whole roof.
Condensation and misting
Condensation forms on the cold underside of either material on a cold night and is a result of moist indoor air, not a leak. Hollow sheets can also gather moisture and algae inside their channels if the end seals fail, which shows as green streaks. Sealed glass units mist when their own seal fails. Both need a repair or replacement of the failed part. A page on condensation in a conservatory roof can separate the harmless kind from the failing kind, and we do the same on a survey.
Privacy and overlooking
A clear glass roof is visible from upstairs windows in the house and from neighbouring ones, in both directions. Opal polycarbonate hides the room from above and blurs the sky, which some owners value. A frosted or tinted layer can be added to glass too. It is worth standing upstairs and looking down at the existing roof before you decide.
How long each lasts, and what shortens it
The published lives for polycarbonate are modest. HomeBuilding says it has a typical lifespan of 10 years, and The Eco Experts (updated 29 April 2024) put it at about 10 to 15 years. These are typical lives, not guarantees, and sheets in shade and good condition can run longer while those baked by afternoon sun run shorter.
What wears out polycarbonate
Sun is the main enemy. Sheets turn yellow and brittle, edges crack where they are fixed and the end seals open up. Dirt and algae settle in the channels. Bars and seals age with them, so the whole roof tends to need attention in the same period.
What wears out a glass roof
The guides we use give no typical life for a conservatory glass roof. The glass may outlast the seals and bars around it. Gaskets harden, bars corrode or lose their finish, and the seal inside a double-glazed unit eventually lets in moisture. Replacing a unit is simpler than replacing a sheet, but the frame has to be sound to hold it.
Planning the replacement
Because the frame and the covering age together, a new covering on a worn frame can disappoint. We check the glazing bars, the ridge, the eaves beam and the lead where the roof meets the house, so the new roof does not fail at an old joint. Our answer on how long conservatory roofs last gives more of the picture.
Signs it is time
Yellowing, cracks along the edges, green streaks inside the sheets, dripping at the bars and a roof that has started to sag between the bars are all signs the covering is done. A single cracked sheet can be swapped. When several have gone, replacing the lot is the better buy, because matching old and new sheets rarely works.
What the published costs cover
Online price ranges for conservatory roofs are wide, and most mix several types of work. MyJobQuote gives replacement at between £3,200 and £6,000 (Oct 2026), and The Eco Experts at between £2,300 and £6,000 (April 2024). Both are typical UK ranges for a conservatory roof in general, not for glass alone or polycarbonate alone, and neither belongs to a local firm.
What moves the price
Size and shape come first, since a bigger or more complicated roof needs more material and more time. The covering is next: thicker multiwall sheets cost more than thin ones, and coated or specialist glass costs more than clear units. Frame work follows. If the glazing bars need replacing, a new roof can cost much more than a straight swap of sheets.
Access and extras
A conservatory in the middle of a garden is easier to work on than one that only a narrow side passage can reach. Scaffolding or access towers add to the price where they are needed. Ventilation openings, electrics for lighting and finishing around the house wall all matter as well.
Checking a quote
Ask any firm quoting for the work whether the figure includes VAT and any scaffolding, what the glazing specification is and what happens to the old roof. A written price that answers those questions is easier to compare than a headline number, and collecting three of them gives you a fair picture of the local market.
Comparing like with like
Two quotes only compare if they describe the same roof: the same covering, the same bars, the same finish at the house wall and the same cleanup. If one quote leaves out the flashing or the guttering, the saving is not real. Put the specifications side by side before you look at the totals.
Weight, the frame and Building Regulations
Glass is heavier than polycarbonate, and a roof of sealed units loads the frame more than a roof of sheets. A frame designed for polycarbonate may need strengthening before glass goes on. The supplier or a structural engineer sets the limit, and we check the condition of the bars, the base and the dwarf walls on the survey.
Does a new roof need approval?
Planning Portal guidance says a replacement conservatory roof must meet the regulations on structure, energy efficiency and ventilation. Four conditions decide the Part L exemption for a conservatory: the room must be at ground level, with a floor area of 30 m² or less, a wall or door between it and the house, and neither house heating nor a fixed heater inside. Whether the roof is solid or glazed, it must meet the Building Regulations, so check with your building control body before you order.
Thermal figures
Where Part L applies, a new rooflight is held to 2.2 W/(m²·K) in Approved Document L (2021 edition), while roof windows have their own row, 1.4 or alternatively a minimum of Window Energy Rating Band B... Document L 2026 starts on 24 March 2027, so the edition in force on your application date matters.
Next step
Compare the two on your own room with a survey: we look at the aspect, the frame and the current covering, and the result goes into a short note for you.
