The short answer
A tiled roof is heavier than the glass or polycarbonate it replaces, and many older frames were never built to carry it. Whether yours can depends on the frame material, the dwarf walls and the foundations beneath them. A roofer cannot judge that by eye alone, so the answer comes from a survey, and sometimes from a structural engineer, before any tile is ordered.
Why tiles change the load on a conservatory
A glazed or polycarbonate conservatory roof is light by design. The sheets or glass units sit in an aluminium or uPVC frame that only has to carry the covering, the wind and a little snow. A tiled roof is built differently. It has rafters, battens, an underlay and a heavy covering, plus insulation and a plasterboard ceiling inside. Every one of those layers adds weight, and the total is a multiple of what the old roof carried.
Tiles are only one layer of it. A finished tiled conservatory roof is a timber or steel structure with a roof laid on top, not a lighter roof dropped onto the old frame. That is why the question is rarely about the tiles alone. It is about whether the whole existing structure can take a different kind of load, and where that load ends up.
For a sense of scale on the covering alone, one reconstituted Cotswold stone slate is listed by its maker at about 84 kg per square metre laid. Lighter tiles and slates exist, but none is as light as a polycarbonate sheet.
What the frame, walls and base must carry
Think of the load as a path. The weight of the roof travels down through the rafters, into the wall plate or frame head, down the frame or dwarf wall, and finally into the ground through the foundation. A weak point anywhere along that path limits what the roof can be.
- The frame. Many conservatories use uPVC frames with slim steel reinforcement, designed for a glazed roof. Some will carry a lightweight tiled roof only if the roof structure bears on something stronger than the frame itself.
- The dwarf walls. A brick or block base wall is usually sound for extra load, but we check the courses, the bonding and any cracking before relying on it.
- The foundations. Many older bases have shallow foundations, and the soil beneath moves with the seasons and with nearby trees. A heavier roof presses harder on a base that may already be marginal.
- The house wall. The ridge or the top of a lean-to roof ties into the main house, so the junction and its flashing must carry the new loads too.
When the frame cannot take the weight, the usual answer is to add support: steel posts or beams bedded on the walls, so that the new roof bears on them and the frames only hold the windows and doors.
Lightweight tiled systems and the checks that follow
Several manufacturers sell prefabricated lightweight tiled roof systems, built around a light steel or aluminium structure with lightweight tile or slate-effect sheets. They are lighter than a conventional timber and tile roof, and they are designed to sit on a conservatory base. Lighter does not mean weightless, and each system comes with its own requirement for the walls and frames beneath it.
That is where the survey does its work. We look at the frame and the dwarf walls, measure the roof, note how the roof joins the house, and compare what we find with what the chosen system needs. If anything is borderline, a structural engineer calculates the loads and specifies the support. We would rather have that answer on paper than guess from the outside.
See our fuller write-up on the lightweight tiled roof for how these systems are built, and the keep your existing frames page for when old frames can stay.
Building Regulations and the weight threshold
Two separate rules apply. First, a solid conservatory roof is material alteration work, so a building control application is needed. Homebuilding & Renovating's guide to updating an old conservatory is clear that a building control application must go in. That covers the structure, the insulation and the way the roof joins the house.
Second, the Planning Portal sets a weight trigger: approval is needed where the new covering leaves the roof covering at least 15 per cent heavier. A move from polycarbonate or glass to tiles will exceed that comfortably, so the structural check is not optional. Approved Document A, the structural part of the Regulations, is the reference for the calculation.
If the job is notifiable, we set out the steps for you and deal with the paperwork. The application goes either to B&NES Building Control or to a registered building control approver, and either route will want to see the structural information. If the conservatory is on a listed house, or the house is in a conservation area, ask B&NES planning first, because a visible change of roof may need consent.
Cost, lifespan and when another roof is the better choice
Tiled conservatory roofs are not the cheapest option, and the structure beneath them adds to the bill. MyBuilder's 2026 guide reports a tiled conservatory roof averaging about £4,000, at £50 to £100 per square metre, as a typical UK range. Frame strengthening, steel and foundation work come on top where the survey calls for them. The fixed quote we give you is written after the survey.
For lifespan, HomeBuilding gives a tiled conservatory roof as lasting in excess of 50 years, against about 10 years for polycarbonate. Both are typical lives, and exposure and the quality of the fitting move them either way.
If the survey shows the base cannot carry a tiled roof at reasonable cost, there are other routes. A lighter solid roof panel system may suit, and you can read about the value a solid roof adds and solid conservatory roofs generally. If insurance is a worry, our note on conservatory roof insurance explains what to tell your insurer.
For the whole range of choices, from glass to tiles, start with our conservatory roof replacement service page. Have the frame and base checked before you commit, since a tiled roof only makes sense if the walls below can carry it.
