The short answer
Yes, in many cases the existing uPVC frames can stay. A like-for-like swap of polycarbonate or glass puts little new demand on them. A heavier solid roof is different, because the frames must carry more weight, so they are checked for condition, movement and strength first. Frames that are bowed, split, leaking or too slim for the load are replaced or strengthened.
When the frames can stay
A conservatory roof sits on the frame, and the frame sits on the dwarf wall. If a roof is swapped for another of similar weight, the frame is carrying much what it carried before. That is the simplest case, and the one that needs the least paperwork, and it is often right for a worn polycarbonate roof being replaced with new sheets or with a glass roof of the same kind.
Keeping the frames saves money and disruption. The windows, doors and wall seals are left alone, and the room is opened up for less time. The frames also keep the look the house already has, which matters on an older property where the conservatory was built to match the windows.
The condition of the frame decides it, not its age. A frame that has been well made and looked after can be sound after many years. A cheaper one can be tired earlier. We judge each one on what we find, not on a rule of thumb. A frame fitted by a careful installer, with proper packers and fixings, is more likely to pass than one that was put up quickly and has been sealed with sealant ever since.
What we check on the frames
On site we work through the frame piece by piece, because a weakness in one place can undermine a new roof.
- Square and level. The frame should sit true. A twist or bow means the roof will not seat evenly and the joints will open.
- Failed seals and misted units. Condensation between the panes means the glazing seal has gone. That is a glazing repair, separate from the roof, but worth knowing about.
- Splits and brittle plastic. uPVC that has gone chalky or cracked at the corners may not hold new fixings well.
- Fixings to the wall. The frame must be firmly secured down to the dwarf wall, and the fixings must not have rusted or worked loose.
- The ring beam or eaves beam. Many conservatories have a rigid beam at the top of the frame that spreads the roof load. If it is missing or too light, it is a structural matter.
Photographs of your own frames go with the findings, so you are looking at the same evidence we are.
Why a heavier roof asks more of the frames
A glass or polycarbonate roof is light. A solid roof, such as a lightweight tiled system with insulation and a plastered ceiling, is a warm roof and weighs more. A uPVC frame is made to hold glazing, and the thin plastic sections are normally reinforced inside with steel. That reinforcement is not designed to carry a heavy roof load across a wide span.
With a solid roof the usual answer is to let the roof carry itself. A structural beam or steel section is built into the new roof, or fixed along the top of the frames, so the weight passes down through posts and not through thin plastic. Building Regulations apply to a solid conservatory roof, and any covering at least 15 per cent heavier than its predecessor brings in approval and a structural assessment. We cover how that works in the guide to structural checks before a solid roof.
So the honest answer for a solid roof is often yes, but with strengthening that you may not see once it is finished. If the frames are too weak for any sensible reinforcement, we tell you at the survey.
When the frames should be replaced
Replacement is the right choice when keeping the frames would cost more in repairs and compromises than it saves.
That is true when the frame is badly bowed, when the corners have split, when the glazing seals have failed across many panes, or when the frame cannot be fixed down safely to the wall. It is also worth thinking about if you plan to change the doors, add a different window layout or turn the conservatory into a proper room. Our guide on turning a conservatory into a room covers that decision.
There is a middle route. Sometimes a few damaged units can be swapped for new ones while the rest stay. New glazing units in an old frame can lift comfort and appearance for less than a full replacement.
New frames also let you choose a different finish. If the existing frames are white and you want a colour, or the other way round, that is easier to do with a new set than by trying to match old plastic that has weathered.
The wall underneath comes into it too
Frames and walls are checked together. A good frame on a cracked or damp dwarf wall will not stay good for long, and a heavier roof will make any weakness below show itself. Our answer on whether you need to rebuild the dwarf walls explains what we look for there.
At the free survey we look at both, photograph your own frames and walls, and tell you clearly which parts can stay. Before the visit, try opening every door and window in the conservatory, because a sash that sticks or drops can point to frame movement we will want to look at closely. Our area is Bath and every town within 30 road miles. You can book the survey by phoning 01225 285181, sending us a WhatsApp message, or filling in the form on this website. For the full picture of that work, see our conservatory roof replacement page.
