Choosing a conservatory roof means trading four things against each other: how comfortable the room is, how much daylight it keeps, what the roof costs, and what permission it needs. No single option wins on all four. Polycarbonate is light and inexpensive but noisy and poor at holding heat. Glass keeps the view of the sky and, in modern solar-control form, handles the sun far better than the old clear panes did. A solid roof, tiled or lightweight, gives the steadiest temperature and the longest life, but it is the heaviest choice, and the only one of the three that is certain to need a Building Regulations application. What follows takes each option in turn, then lines them up in a table, then explains how to decide. Each figure comes from published third-party guides and should be read as typical for the UK, not as a quote.
Polycarbonate: light, quick and short-lived
Polycarbonate roofing is plastic sheet, normally twin-wall or multi-wall, with a honeycomb of tiny channels inside. Nothing lighter can be laid on a conservatory frame, so slim frames take it easily and a great many older rooms were built with it. Fitting is quick, and it is the simplest of the three to replace.
The drawbacks are well known. It insulates poorly, so the room is warm in sun and cold the rest of the time. It is noisy when rain or hail falls on it. It clouds and yellows with age, and algae can grow in the cells once the end seals fail. Published lifespans are short by roofing standards: HomeBuilding gives about 10 years, and The Eco Experts give 10 to 15 years. New sheets can go into old bars if the bars are sound, a point taken up in the sheet replacement answer, while the warning signs of a tired roof appear in the polycarbonate lifespan answer.
Polycarbonate suits a room that is used lightly, a frame that cannot take more weight, or a budget that rules out anything else. For a room meant to be lived in all year, it is the weakest of the three.
Glass: bright, clear and heavier
A glass roof sets the conservatory apart from the rest of the house. You see the sky, trees and weather through it, and on a bright winter day it is a lovely place to sit. Modern units are far more capable than the single or basic double glazing of older roofs. They carry coatings that reflect part of the sun's heat, and a self-cleaning outer surface helps keep them clear.
Glass weighs more than sheet, which puts demands on the bars and frame, and units are generally changed as a full set. It holds heat better than polycarbonate, but it still cannot match a built-up solid roof, so the room can overheat under a south-facing roof and lose warmth quickly at night. HomeBuilding reports a life in excess of 30 years for a glass roof, which is much longer than polycarbonate. The units are described more fully in the modern glass roof guide.
Glass suits people who value the light above all and are prepared to manage the heat with blinds and ventilation. It also suits a room that sits in shade for part of the day, where overheating is less of a worry.
Solid: tiled or lightweight
A solid roof replaces the transparent covering with an insulated build-up and an opaque finish. Two kinds exist. The tiled roof is built from timber rafters, insulation, battens and real tiles or slate. The lightweight roof uses insulated panels or tile-effect sheets, and loads the frame far less.
Comfort is the strongest argument. The insulation holds heat in winter and stops the sun pouring in during summer, so the room can be used for much more of the year. For longevity, The Eco Experts quote around 50 years or more for a solid roof, and HomeBuilding says tiled conservatory roofs run past 50 years. The costs are a higher first price, a darker room unless you plan for roof windows or a lantern, and a structure that must be checked before the roof is chosen. How each kind is assembled is shown in the guide to solid roofs.
Appearance counts here as well. On a stone house in Bath, a conservatory roof is seen against the main roof, and a tiled finish chosen to sit with it looks like part of the building, whereas a pale plastic sheet looks like an afterthought. Where the house is old, the same habit applies that we follow on the main roof: the covering on the extension is matched to the covering on the house, and slate stays slate. A lightweight tile-effect sheet can approximate that look when the frame cannot take real tiles, although it will not match it up close.
Solid roofs also bring paperwork. Because the work is a material alteration, the roof needs a building control application. We explain the checks in our regulations guide.
The three side by side
This table puts the options next to each other. Costs are the typical UK figures from MyBuilder (2026) and lifespans are from HomeBuilding and The Eco Experts, so treat them as guides.
| Option | Comfort | Light | Typical life | Approval |
|---|---|---|---|---|
| Polycarbonate | Poor; hot and cold, noisy in rain | Diffuse, a little dull | About 10 to 15 years | Check with building control |
| Glass | Fair with solar-control units | Bright and clear | Over 30 years | Check with building control |
| Lightweight solid | Good, steady temperature | Less, unless roof windows are added | Depends on system | Building Regulations application |
| Tiled solid | Best, closest to the house | Less, unless roof windows are added | Over 50 years | Building Regulations application |
The overall cost range reported for conservatory roof replacement is £2,000 to £10,000 and above, with an average of about £4,500 and a tiled roof averaging about £4,000. What moves the figure within each option is set out in the cost guide. One thing the table cannot show is the effect of the frame, which is why a survey comes before any choice.
It also cannot show running costs and repairs. A roof that holds heat reduces the draw on a heater in the cold months, while a roof that needs resealing, cleaning or patching every few years adds small bills that rarely appear in a first quote. When two options come out close on price, the one with the longer published life and the steadier room usually repays the difference.
How the frame decides what is possible
The options are not equally open to every conservatory. Polycarbonate asks the least of the frame. Glass asks more. A tiled roof asks the most, and a lightweight system sits in between depending on the product. A conservatory with a slim, old frame, or low walls on shallow foundations, may be limited to the lighter options unless it is strengthened.
So the structure comes first on our visit, ahead of any talk of finishes. We check the glazing bars or rafters, the ridge, the junction with the house and the head of the walls, and we look at the base. Sometimes a ring beam added at the top of the walls spreads the load enough to carry a heavier roof, and sometimes the better answer is to choose a lighter one. The full list of checks is in the structure guide.
Choose the roof the structure can carry, then decide how it should look. Choosing the finish first is how a project stalls at the survey.
Comfort, light and the room you actually use
Noise and condensation deserve a mention before the comfort question. Rain on polycarbonate can drown out a conversation, while a solid roof muffles it. Condensation tends to gather on cold surfaces, and a roof that stays warm on the inside gives it less to form on. Neither point appears on a price list, yet both shape how the room feels on a wet winter evening.
The best way to pick is to describe how you use the conservatory. A room that serves as a dining area or a home office through the winter wants a steady temperature, and a solid roof delivers that most reliably. A sun room that you use on fine days and leave on dull ones may be better with glass. A utility space, a store or a seldom-visited extension may justify polycarbonate.
Think also about who else uses the room. A conservatory that doubles as a play area or a space for an elderly relative needs a roof that does not bake in July or chill in January, and a household that only passes through it can accept more of a compromise. Write down the hours of the day the room is used and the months when it is hardest to bear, and give that list to whoever comes to survey.
Orientation matters too. A south-facing conservatory with a glazed roof gathers a great deal of sun and often overheats, while a north-facing one collects little and stays chilly. A solid roof moderates both. If you love light, the options can be mixed: a solid roof with roof windows or a lantern gives daylight from above, and the glazing held to the thermal limits in Approved Document L (Table 4.2 sets 1.4 W/m²K as the limit for roof windows and 2.2 W/m²K for rooflights). Roof windows in a solid roof are dealt with in their own answer.
Listed buildings and the Bath conservation area add a final consideration. The Bath conservation area covers roughly half the city, and B&NES Council is the body that grants listed building consent. A change to a conservatory on a listed house is a matter to settle with the council before you choose; the planning answer says where to start.
What happens after you choose
Once you have settled on a type, the sequence is the same whichever you pick. First comes the survey, with photographs of the roof and frame and a written view on whether the structure allows your chosen option. If it is a solid roof, we prepare what building control needs. The price is then agreed and written down. Off comes the old roof, up goes the new one with the wall junction flashed and the room made weathertight, and the debris leaves with us once the roof is complete and the site is swept. Keep the old roof's measurements and any frame paperwork you have, since they help when choosing blinds, lights or a ceiling finish later. Timescales vary with the roof chosen, and the timescale answer gives the usual pattern.
If you are still undecided, begin with the hub page on conservatory roof replacement, or ring 01225 285181 to arrange the visit.