How heavy are conservatory roof panels, and will my frame cope?

Weight is usually the first worry, and a fair one. Your conservatory frame was built to hold a particular roof, and nobody wants to load it with something it was never meant to carry. The short answer is reassuring: modern insulated aluminium panels are light enough for the great majority of uPVC and aluminium frames in sound condition, and next to a full replacement roof with a new frame they weigh far less. Here is why, with numbers you can check for yourself.

What a panel is made of

Each panel is a sandwich. Two thin aluminium skins sandwich a 75 mm layer of solid foam insulation, glued to it on both faces. The foam looks solid, but most of its volume is gas held in tiny closed cells, well over 95% of it. That is what makes it such a good insulator, and it is also why a thick panel weighs so little for its size.

The strength comes from the bond. Skins glued firmly to a core behave like a beam: the core keeps the skins apart, and the skins resist bending. That lets a light panel span between your roof bars without sagging, where a single sheet of the same weight would flop.

How the roof options compare

These are typical figures for the roof covering only, per square metre, and for a 14 m² roof, the size of a common Edwardian or Victorian. We do not publish a single kg figure for our panels, because it varies with size and colour finish, but we can say where they sit in the order.

A note on the last row: the lightest full replacement roofs are advertised at around 30 kg per m². A 12.5 mm plasterboard ceiling adds about 8.5 kg per m² on its own, before the skim coat, and many systems use more than one layer. That is why those roofs usually come with a new ring beam and sometimes new posts.

Worked example one: a glass roof coming off

Say you have a 3.5 m by 4 m Victorian conservatory with its original sealed glass roof. With the facets included, the roof is about 15 m². At 20 kg per m², the glass alone weighs about 300 kg, and more if the inner pane is laminated or thicker.

Swap that for panels and the roof gets lighter, often by a large margin. The frame that carried glass for 20 years is now carrying less. This is the easiest case we see. Read more on our page about replacing a glass roof.

Worked example two: a polycarbonate roof coming off

Now a lean-to measuring 3 m each way, with a 16 mm polycarbonate roof, about 9.5 m² once the slope is counted. The sheets weigh about 28 kg in total. Panels weigh more than that, so here the roof does get heavier.

Honest point: some polycarbonate roofs were built with lighter roof bars than glass roofs, because they only had to carry plastic. In most sound frames the bars cope well with panels. Where a bar is bent, undersized or poorly fixed, we find it at the survey and say what needs doing before we quote. See what the change involves on our polycarbonate replacement page.

The roof's own weight is only part of the load

• Snow. Ten centimetres of fresh snow can add around 10 kg per m², and wet, settled snow two or three times that. The frame has to carry this on top of the roof itself.
• Wind. A light roof must be held down firmly. On a gusty day, suction can pull upwards on a roof harder than its weight presses down, so the fixings matter as much as the weight.
• People. Nobody should stand or kneel on the roof, whatever it is made of. A person puts their whole weight through a spot the size of a shoe, which no conservatory roof is designed for.

What decides whether your frame is suitable

Condition matters more than weight. A straight frame on a sound base will take panels almost every time. A base that has cracked, or a frame that has dropped at a corner, needs sorting before any new roof, however light. We check this at the survey; our guide to what happens at a survey covers it step by step.

Building control is part of the same picture. Going solid takes the room outside the conservatory exemption, which normally brings in building control, and the officer will want to be satisfied the structure carries the new roof. We send the product details and our survey findings with the application, and we agree the specification before anything is made. Timber frames are looked at case by case, because hidden rot matters more than weight.

On fitting day

Each panel is light enough for two fitters to carry up a ladder and set into the bars by hand. There is no crane, no hoist and no pile of heavy materials on your lawn. The old sheets or glass leave with us for recycling. Expect one day on site for a small roof, and a day or two for a medium one. More on the day itself is on our how we work page.

Check your own roof

Tell us the size, the style and what is on the roof now, and we will tell you where it sits. Small roofs start from £3,000, medium from £4,000 and large from £5,000, fitted with the building control application included. Compare the options on our roofs page, then get my price.